Modeling of acute spinal cord injury in the rat: neuroprotection and enhanced recovery with methylprednisolone, U-74006F and YM-14673

We used a new injury device that produces consistent spinal cord contusion injuries (T8) in rats to compare the behavioral and histologic effects of methylprednisolone sodium succinate (MPSS) administration, the clinical standard of therapy after acute spinal cord injury (ASCI), with the 21-aminosteroid, U-74006F (U74), and the TRH analogue, YM-14673 (YM), at different trauma doses. Three sequential experiments were conducted: Experiment 1. U74 (3.0/1.5/1.5 mg/kg; 10/5/5 mg/kg; 30/15/15 mg/kg), MPSS (30/15/15 mg/kg), or vehicle were administered intravenously (i.v.) at 5 min, 2 and 6 h after the injury (n = 8/group). U74 (10/5/5 mg/kg) and MPSS animals scored better than controls (Days 8-43) in open field walking (OFW); no other differences were seen between groups. Experiment 2. Dose-response evaluation of MPSS determined more effective doses. Groups (n = 16) receiving 30/30/30/30 mg/kg and 60/60/60/60 mg/kg i.v. at 5 min and 2, 4, and 6 h after the injury had better OFW scores than controls (Days 8-29; Day 29). Both groups performed better than controls (Days 8-29) on inclined plane (IP); 30 mg/kg animals scored higher on Day 29. Percentage tissue spared (%TS) at the lesion center was greater for 60 mg/kg animals (23.4%) than controls (17.3%). Experiment 3. Compounds were administered as in experiment 2 (n = 15/group); MPSS (60/30/30/30 mg/kg) and YM (1/1/1/1 mg/kg and 1 mg/kg/day ip) were most effective. YM and MPSS combination produced no additive effects. YM animals scored better than MPSS and control animals in OFW (Days 8-29) and better than controls on IP (Days 8-29; Day 29) and grid walking (Day 29). MPSS animals scored better than controls on IP (Days 8-29). YM and MPSS groups had greater %TS than controls. This series of experiments demonstrates the utility of this injury model and simple behavioral measures for preclinical assessment of pharmacologic agents. Under these experimental conditions, U74 demonstrated equivalent efficacy to MPSS, and YM demonstrated greater efficacy than MPSS in the treatment of ASCI.     

Increased production of eicosanoids, TXA2, PGI2 and LTC4 in experimental spinal cord injuries

Arachidonate metabolites have many kinds of bioactivities. Thromboxane A2 (TXA2) stimulates platelet aggregation and vasoconstriction, whereas prostaglandin I2 (PGI2) antagonises its activities. Thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) are determined in biological materials. Production of TXB2, 6-keto-PGF1 alpha and leukotriene C4 (LTC4), which have potent vascular permeability, was measured by radioimmunoassay in experimental spinal cord injured animals. TXB2 level in the rat spinal cord reached a peak concentration of 133.6 +/- 3.8 pmol/g cord, and 6-keto-PGF1 alpha increased to 26.2 +/- 11.7 pmol/g cord 5 minutes after the injury. There was good correlation between TXB2 production and vascular damage as monitored by fluorescein uptake. When OKY-046 ((E)-3-[4-(1-imidazolylmethyl) phenyl]-2-propenoic acid), which selectively inhibits TXA2 synthetase activity, was administered 10 minutes before injury, the increase in TXB2 production was inhibited by more than 80%, but the degree of vascular damage was reduced by only 40%. In the guinea pig spinal cord, LTC4 levels reached a peak concentration of 2.2 +/- 0.4 pmol/g cord 10 minutes after compression, while that of TXB2 reached 146.8 +/- 6.2 pmol/g cord. The increased production of TXB2 was correlated with the degree of compression injury while that of LTC4 production did not. These findings suggest that vasoactive eicosanoids, TXA2, PGI2 and LTC4, play important roles in secondary damage following spinal cord injury, although their roles may be different among species of animals.     

Effects of methylprednisolone on lesioned and uninjured mammalian spinal neurons: viability, ultrastructure, and network electrophysiology

An in vitro investigation was undertaken to provide information regarding the effectiveness of methylprednisolone sodium succinate (MPSS) as a treatment for the primary mechanical injury of spinal cord (SC) trauma. Exposure of uninjured mouse SC cells to MPSS for 24 h caused neuronal stress when the concentration exceeded 150 micrograms/mL; neuronal death occurred at concentrations above 600 micrograms/mL. The concentration range for MPSS protection of SC neurons subjected to a defined physical injury (laser microbeam transection of a primary dendrite 100 microns from the perikaryon) was very narrow: survival in the 30 micrograms/mL group differed significantly from the untreated control group (68.5% +/- 14.1 vs. 47.1% +/- 14.1), treatment with 20 or 60 micrograms/mL MPSS did not increase survival, and treatment with 100 micrograms/mL MPSS accelerated ultrastructural deterioration and increased the likelihood of death. Enhanced survival of lesioned neurons was observed when 30 micrograms/mL MPSS was applied within 15 min of dendrotomy but not when MPSS was administered 2 h after lesioning. Multimicroelectrode plate (MMEP) studies of SC network electrical activity indicated that MPSS associated readily with neuronal membranes. This finding was consistent with the hypothesis that MPSS may protect lesioned neurons by stabilizing damaged membranes, enhancing lesion resealing, and limiting the spread of ion-mediated damage. However, comparisons of neurite die-back 24 h after dendrotomy found no significant difference between MPSS-treated and control neurons. Application of 30 or 100 micrograms/mL MPSS increased the spontaneous burst activity of SC networks grown on MMEPs, however, there was no evidence that the increased excitability at these concentrations was the result of specific actions of MPSS on GABA or NMDA synapses.     

Permanent paraplegia following epidural and general anesthesia: two case reports

Two strains of rats, Sprague-Dawley and Wistar, were assayed in order to determine which strain is the more suitable experimental model for the study of pharmacokinetic alterations induced by spinal cord injury. Animals were submitted to spinal cord contusion at the T8-T9 level by the weight drop method. A single acetaminophen oral dose (100 mg/ kg) was administered 24 h after injury and blood samples were drawn for a period of 4 h. Acetaminophen concentration in whole blood was determined by high performance liquid chromatography and pharmacokinetic parameters were estimated. For both strains, Cmax and AUC were significantly lower, whereas tmax remained unchanged, in injured animals compared to sham-injured controls. Circulating acetaminophen concentrations were higher; therefore, pharmacokinetic alterations were more easily discerned, in Sprague-Dawley than in Wistar rats. It is concluded that the Sprague-Dawley strain is a more suitable model for the study of pharmacokinetic alterations induced by spinal cord injury.     

The risk of disease progression is determined during the first year of human immunodeficiency virus type 1 infection

The contribution of CD4 and CD8 cells to crescentic glomerulonephritis (GN) was studied in mice genetically deficient in CD4, CD8, and with combined CD4 and CD8 (CD4/CD8) deficiency. Wild-type (C57BL/6) mice developed GN with mild proliferative changes 7 days after an intravenous dose of sheep anti-mouse glomerular basement membrane globulin. Crescents were observed in 12.5 +/- 6.1% of glomeruli on day 14. On day 21, 51.5 +/- 7.3% of glomeruli were affected by crescents, and mice had marked azotemia and proteinuria. CD4 and combined CD4/CD8-deficient mice developed minimal evidence of GN. On day 21, their glomeruli showed only mild proliferative changes and crescents, azotemia, and proteinuria were absent. In contrast, CD8-deficient mice developed severe crescentic GN with three of five mice dying on day 20 with ascites and edema. The two mice surviving to day 21 had severe azotemia. Crescent development was accelerated (day 14, 51.6 +/- 2.4% of glomeruli; day 20 or 21, 62.0 +/- 4.0% of glomeruli). These studies demonstrate that CD4 cells are crucial for the development of crescentic GN in mice and that genetic absence of CD8 cells accelerates disease. They support the hypothesis that crescent formation is a manifestation of CD4-dependent (and CD8-independent) delayed type hypersensitivity in the glomerulus.     

Brain-derived neurotrophic factor stimulates hindlimb stepping and sprouting of cholinergic fibers after spinal cord injury

Neurotrophic factors have been proposed as a therapeutic treatment for traumatic brain and spinal cord injury. The present study determined whether exogenous administration of one such factor, brain-derived neurotrophic factor (BDNF), could effect behavioral recovery and/or histopathological changes after spinal cord injury. Adult rats received a mild or moderate contusion injury or complete transection of the mid-thoracic spinal cord. Immediately thereafter, they were infused intrathecally with vehicle or BDNF for 28 days. Behavioral recovery was evaluated for 6 weeks after injury, at which time the rats were sacrificed and the spinal cord tissue was examined histologically. The infusion of BDNF resulted in acute stimulation of hindlimb activity. These effects included activation of alternating airstepping in injured rats when the hindlimbs were unloaded as well as slight improvements in the rate of recovery in open field locomotion score. BDNF infusion was also associated with enhanced growth of cholinergic fibers at the injury epicenter, but did not affect white matter sparing or density of serotonergic axons at or below the injury site. Based on immunohistochemical detection of BDNF protein distribution, these described effects are likely to be mediated by the activation of cells and axons within the central injury region and the along the peripheral rim of the spinal cord. Together, these findings demonstrate that the exogenous infusion of BDNF after spinal trauma can influence postinjury outcome through mechanisms that include acute stimulation of hindlimb activity and neuritogenesis at the injury site.     

Characteristics of human fetal spinal cord grafts in the adult rat spinal cord: influences of lesion and grafting conditions

The present study evaluated the growth potential and differentiation of human fetal spinal cord (FSC) tissue in the injured adult rat spinal cord under different lesion and grafting conditions. Donor tissue at 6-9 weeks of gestational age was obtained through elective abortions and transplanted either immediately into acute resection (solid grafts) or into chronic contusion (suspension and solid grafts) lesions (i.e., 14-40 days after injury) in the thoracic spinal cord. The xenografts were then examined either histologically in plastic sections or immunocytochemically 1-3 months postgrafting. Intraspinal grafts in acute lesions demonstrated an 83% survival rate and developed as well-circumscribed nodules that were predominantly composed of immature astrocytes. Solid-piece grafts in chronic contusion lesions exhibited a 92% survival rate and also developed as nodular masses. These grafts, however, contained many immature neurons 2 months postgrafting. Suspension grafts in chronic contusion lesions had an 85% survival rate and expanded in a nonrestrictive, diffuse pattern. These transplants demonstrated large neuronally rich areas of neural parenchyma. Extensive neuritic outgrowth could also be seen extending from these grafts into the surrounding host spinal cord. These findings show that human FSC tissue reliably survives and differentiates in both acute and chronic lesions. However, both the lesion environment and the grafting techniques can greatly influence the pattern of differentiation and degree of host-graft integration achieved.     

Secretion and Sex differences in cord serum growth hormone levels of the human fetus (author's transl)

Cord venous growth hormone (GH) and somatostatin levels were measured by radioimmunoassay in 86 infants and 11 anencephalic infants. 1) Cord GH levels were 69.2 +/- 20.2 ng/ml (N = 6, gestational weeks (GW) : 21-30W, mean +/- S.D.), 31.5 +/- 24.3 ng/ml (N = 11, GW : 31-36W), and 17.6 +/- 8.9 ng/ml (N = 71, GW: 37-41). In anencephalic infants, cord GH levels were significantly lower (2.3 +/- 1.4 ng/ml) than those in preterm and fullterm infants. 2) In fullterm infants, cord GH levels of small infants (19.2 +/- 9.2 ng/ml, N = 33, birth weight less than 3,250g) were significantly higher than that of large infants (15.1 +/- 8.1 ng/ml, N = 38, birth weight greater than of equal too 3,250g). On the other hands, cord somatostatin levels were relatively lower in small infants than in large infants. 3) There was a significant difference between male cord GH levels (20.6 +/- 8.9 ng/ml, N = 35) and female cord GH levels (14.6 +/- 8.0 ng/ml, N = 36). These results suggest that fetal GH secretion is suppressed by GH inhibiting factor (somatotropin release inhibiting factor) from mid gestation toward term and there is a sex difference of fetal GH secretion in fullterm fetus.     

Isolated proteinuria in asymptomatic patients

Regional cerebral blood flow (rCBF) was measured by 133Xe inhalation in 17 patients with chronic spinal cord transection. This was done to investigate any effects such spinal cord deafferentation might have on resting rCBF and to test whether resulting chronic preganglionic sympathectomy influenced cerebral vasomotor CO2 responsiveness and autoregulation. Thirteen patients had complete cervical cord transection (CCT) at levels C4--C6 (age 37 +/- 15 years, time interval, 2 months--20 years). Four patients had complete thoracic cord transection at levels T3--4, T8 and T12 (TCT; age 49 +/- 22 years; time interval 2--5 months). CO2 responsiveness was tested by induced hypercapnia in 11 patients with CCT and 2 patients with TCT. Autoregulation was tested in 10 patients with CCT and 4 patients with TCT by decreasing cerebral perfusion pressure during postural tilting. Mean resting hemispheric Fg values (MHFg) were significantly reduced only in patients with CCT (MHFg = 69 +/- 12 ml/100 g brain/min), while brain stem-cerebellar Fg values (BSC Fg) were reduced significantly both in patients with CCT (BSC Fg = 85 +/- 10) and with TCT (BSC Fg = 88 +/- 12) compared to values measured in healthy normals (N = 21, MHFg = 81 +/- 10, BSC Fg = 98 +/- 10). Hemispheric CO2 responsiveness showed a trend toward reduction in patients with CCT but this was not statistically significant. Hemispheric autoregulation was significantly impaired in CCT compared to healthy normals but improved with time and rehabilitation.     

Characteristics of gene 28 product, the constituent of the central part of bacteriophage T4 baseplate

This study investigated the effects of indomethacin at clinically relevant doses and its chronic usage on intestinal pathology, survival time and intestinal tissue 6-keto prostaglandin F1 alpha and leukotriene B4 level in rats during various periods with different doses. Indomethacin was administered ranging from 0.625 to 5 mg/kg. When used in doses of 0.625 and 1.25 mg/kg, indomethacin caused no apparent intestinal lesions or death during a treatment period of 30 days. On the other hand, all rats died in 7 days when 5 mg/kg of indomethacin was given. Mortality rate reached 53.3% in seven days in the group where 3.75 mg/kg indomethacin was given. The minimal dose of indomethacin, which induced intestinal ulcer and death, was 2.5 mg/kg. The main pathological findings were intestinal ulcers, but no macroscopic and microscopic changes were observed in the stomach. Intestinal tissue 6-keto prostaglandin F1 alpha and leukotriene B4 levels were quantified by enzyme immunoassay after homogenisation and extraction of tissue. In dose-dependent studies, only the dose of indomethacin, 3.75 mg/kg, significantly inhibited intestinal tissue 6-keto prostaglandin F1 alpha levels during seven days application period (197.39 +/- 24.26 vs 383.66 +/- 46.68 ng/g tissue, treatment vs control). 2.5 mg/kg of indomethacin caused no intestinal ulceration on 4th day, however, it significantly inhibited intestinal tissue 6-keto prostaglandin F1 alpha levels on 4th day in time-dependent studies (190.3 +/- 26.62 vs 383.66 +/- 46.68 ng/g tissue, treatment vs control). Neither dose-dependent nor time-dependent indomethacin administration changed intestinal tissue leukotriene B4 level. The results of this study indicated that indomethacin produced enteropathy rather than gastropathy when used chronically in clinically relevant doses in rats. Inhibition of prostaglandin synthesis, which was estimated by quantification of intestinal tissue 6-keto prostaglandin F1 alpha level, seemed not to be a prerequisite for its enteropathic effect.     

Effects of chronic angiotensin-converting enzyme inhibition on left ventricular and myocyte structure and function during recovery from chronic rapid pacing

LV and myocyte function and angiotensin converting enzyme (ACE) activity with ACE inhibitor (ACEI) treatment were examined in four groups of dogs (n = 6 each): (1) control; (2) with 4 weeks of recovery from chronic rapid pacing (REC: 216 beats/min), (3) ACEI for the first 14 days of REC (ACEI--14), and (4) ACEI for 28 days of REC (ACEI--28). Three additional control dogs were administered ACEI for 28 days. LV mass increased with REC compared to control (146 +/- 6 v 92 +/- 3 g, P < 0.05), was unaffected with ACEI--14, and was decreased with ACEI--28 compared to REC (111 +/- 8 g, P < 0.05). Myocyte function was decreased in REC compared to controls (43 +/- 3 v 63 +/- 3 microns/s, P < 0.05) and was similarly reduced with ACEI--14. However, with ACEI--28, myocyte shortening velocity was increased compared to REC (56 +/- 1 microns/s, P < 0.05). Myocyte beta-adrenergic response was decreased with REC and ACEI--14 compared to controls (53 +/- 9 and 57 +/- 14, respectively v 127 +/- 14 microns/s, P < 0.05). ACEI--28 resulted in a normalization of myocyte beta-adrenergic responsiveness (108 +/- 3 microns/s). LV myocardial ACE activity increased in REC compared to control (5.82 +/- 0.21 v 3.51 +/- 0.15 nmol/mg/min, P < 0.05). With ACEI--14 or ACEI--28, myocardial ACE activity was decreased compared to REC (4.16 +/- 0.06 and 4.08 +/- 0.23 nmol/mg/min; P < 0.05). In control dogs administered ACEI, there were no differences in any of these parameters compared to controls. The unique findings in this study were: (1) effects of ACEI treatment in this model of LV hypertrophy were time dependent with respect to LV mass and LV and myocyte function; and (2) the effect of ACEI treatment on the degree of LV hypertrophy appears to not be solely due modulation of myocardial ACE activity.     

Management of 53 cases of testicular trauma

Fifty-three patients with testicular injury were investigated. Four (8%) had bilateral testicular injury and 15 (28%) had associated injuries, such as penile, spermatic cord, epididymal disruption, thigh, urethral, perineal skin avulsion, femoral vessel disruption and axillary venous injury. The mode of testicle trauma was blunt in 36 (63%) and penetrating in 21 (37%) cases. Early exploration was done in 43 (81%) patients including 4 with bilateral testicular injury: hematoma evacuation in 23 (49%), partial orchiectomy in 16 (34%) and total orchiectomy in 8 (17%) cases, respectively. Otherwise, delayed exploration, due to the late presentation of more than 3 days after trauma, was done in the remaining 10 (19%) patients: hematoma evacuation in 6 (60%) and partial orchiectomy in 4 (40%) cases. The testicle salvage rate was 49/57 (86%), depending on the nature of testicular trauma. Hospitalization for uncomplicated cases was 4.82 +/- 1.85 days, with prolongation to 10.79 +/- 3.64 days (p < 0.05) for patients having associated injuries. Exploration is advocated in all cases of hematocele, irrespective of testicle contusion or rupture. As minimal, the blood-clot from the tunica vaginalis sac should be evacuated, which would relieve disability and hasten recovery.     

A new method for estimating spinal cord function. Refractory period of conductive spinal cord evoked potentials

STUDY DESIGN: This study was designed to examine the possibility of a new spinal cord monitoring method using measurement of the refractory period to monitor spinal cord function. OBJECTIVES: To determine whether measuring the refractory period and the recovery rate of conductive spinal cord evoked potential is a useful method for estimating spinal cord function. BACKGROUND: Measuring the refractory period and constructing the recovery curve have been used to investigate peripheral nerve function. Spinal cord evoked potential elicited by the single stimulus usually is used to evaluate spinal cord function, and it has been said that 50% attenuation of the amplitude is the critical alarm level. METHODS: In anesthetized cats, amplitude, area, and latency were measured on a personal computer from subtracted data collected with a paired-stimulation technique. The authors constructed recovery curves of ascending and descending conductive spinal cord evoked potentials and measured the refractory period during spinal cord compression. RESULTS: When the amplitude of the ascending spinal cord evoked potential began to decrease during spinal cord compression, the amplitude of the response elicited by the second stimulus with interstimulus intervals of 0.8 msec and 1.0 msec decreased more significantly. When the amplitude of the ascending spinal cord evoked potential decreased to 50% of the precompression amplitude, the mean value of the absolute refractory periods of the ascending and descending spinal cord evoked potentials became prolonged from 0.40 +/- 0.007 msec to 0.53 +/- 0.014 msec, and the mean values of their amplitude and area recovery rates decreased from 75% +/- 1% to 35% +/- 2% (interstimulus interval, 0.8 msec) and from 81% +/- 1% to 46% +/- 2% (insterstimulus interval, 1.0 msec). CONCLUSIONS: The change of the responses elicited by the paired stimuli is more sensitive than those elicited by the single stimulus in the spinal cord evoked potentials. The absolute refractory periods and the recovery rate during 50% attenuation of the precompression amplitude is the critical alarm level in spinal cord monitoring.     

The effect of interferon and desferrioxamine on serum ferritin and hepatic iron concentrations in chronic hepatitis B

BACKGROUND/AIMS: Recent reports indicate that an individual's iron status might affect the response rate achieved with Interferon therapy for the treatment of chronic viral hepatitis. METHODOLOGY: Forty individuals, 29 men and 11 women, with chronic viral hepatitis B, who had elevated serum ferritin levels, were randomized to receive either Interferon (IFN) 5 MU TIW SQ for 6 months alone (n=21) or Interferon in combination with repetitive cycles of desferrioxamine infused at a dose of 80 mg/kg per cycle (n=19) over 3 consecutive days in an effort to reduce their metabolically active iron pool during the course of IFN treatment. These cycles were continued until a serum ferritin level of less than 250 ng/ml (normal values <220 ng/ml) was achieved. Additionally, all desferrioxamine treated subjects were placed on a low iron containing diet. An interferon response was defined as normalization of the serum ALT and seroconversion from eAg positive to eAb positive. All other responses were defined as failures. RESULTS: The mean ages of the subjects in the 2 groups were 39+/-6 and 38+/-5 years. The initial serum ALT levels were 150+/-27 and 151+/-13 IU/l. The hepatic iron concentrations were 916+/-29 and 896+/-15 microg/g/dry liver weight. The serum ferritin levels were 386+/-12 and 393+/-18 ng/ml. None of these values differed significantly between the 2 treatment groups. The desferrioxamine treated group consisted of 14 men and 5 women. This group experienced a reduction in their serum ferritin to a level of 237+/-13 ng/ml as a result of the desferrioxamine treatment (p<0.05). Additionally, a reduction in their hepatic iron concentration, to a level 766+/-29 microg/g/dry liver weight, occurred with treatment (p<0.05). Twelve of the 19 (63%) desferrioxamine-treated subjects and 8 of the 21 (38%) control subjects experienced a normalization of their serum ALT levels with treatment (p<0.05). Thirteen of 19 (68%) of the desferrioxamine-treated subjects but only 8 of 21 (38%) of the IFN alone treated group seroconverted to anti-e positive (p<0.05). Moreover, a greater improvement in the hepatic histologic score and rate of HBV-DNA loss occurred in the desferrioxamine-treated group. CONCLUSIONS: Based upon these data, it can be concluded that desferrioxamine infusion to achieve a normal serum ferritin level enhances the likelihood of an individual with chronic hepatitis B responding to IFN therapy. The precise mechanism responsible for this phenomenon is not clear, but would appear to be due to a reduction in the hepatic free iron pool as reflected by sequential changes in the serum ferritin and hepatic iron concentrations.     

Relationship between cytochrome P450 2E1 and acetone catabolism in rats as studied with diallyl sulfide as an inhibitor

Previous studies have demonstrated that cytochrome P450 2E1 (P450 2E1) catalyzes the oxidation of acetone in vitro. The present study was designed to determine the importance of P450 2E1 in the catabolism of acetone in rats using diallyl sulfide (DAS) as an inhibitor of this enzyme. After a single intragastric dose of DAS, blood samples were collected from rats at different time points, and blood acetone concentrations were measured by gas chromatography. In a low DAS dose (50 mg/kg body weight) group, the maximum acetone level of 6-fold higher than the normal level was reached at 6 hr; the acetone level returned to normal at 48 hr. In a high dose (200 mg/kg) group, the maximum acetone level of 9-fold higher than the normal level was reached at 12 hr; the acetone level returned to normal at 60 hr. The turnover time and fractional turnover rate of elevated acetone were 15.8 +/- 0.5 hr and 0.054 +/- 0.001 hr-1, respectively, for the low dose, and 19.2 +/- 0.6 hr and 0.046 +/- 0.005 hr-1, respectively, for the high dose. In a chronic experiment, DAS (50 and 200 mg/kg, i.g.) was given to rats daily for 29 days, and elevated blood acetone levels were observed during the entire experimental period: 2.0 to 2.8 micrograms/mL for the low dose and 3.4 to 3.9 micrograms/mL for the high dose at 24 hr after the 1st, 7th, 14th and 28th doses versus 0.8 to 0.9 micrograms/mL for the control. The increase of blood acetone level was closely related to the decreases of N-nitrosodimethylamine (NDMA) demethylase activity and P450 2E1 content in liver microsomes. Consistent with the lack of cumulative effect from the multiple doses of DAS on acetone level, rather stable levels of the DAS metabolites, diallyl sulfoxide (45.0 micrograms/mL, range: 33.8 to 58.6 micrograms/mL) and diallyl sulfone (11.7 micrograms/mL, range: 6.9 to 15.6 micrograms/mL), were observed at 24 hr after the 1st, 7th, 21st and 28th doses with DAS (200 mg/kg) in the chronic experiment. It is likely that the inactivation and inhibition of P450 2E1 by DAS and its metabolites block the oxidation of acetone and cause its elevation in blood. The results strongly suggest an important role of P450 2E1 in acetone catabolism under physiological conditions.     

The treatment of non-gonococcal urethritis with single dose oral azithromycin

In an uncontrolled study, the efficacy of azithromycin in the treatment of non-gonococcal urethritis was assessed in 41 male patients aged between 20 and 40 years with a mean age of 27 +/- 5 years. Clinical and microbiological diagnosis confirmed that 28 men were found positive for Chlamydia trachomatis, 10 for Ureaplasma urealyticum and three for both C. trachomatis and U. urealyticum. All patients received 1 g azithromycin orally (four 250 mg capsules). The length of time between the treatment and following visits were 7-10 days and 14-21 days for second and third visits, respectively. Complete eradication was achieved in 27 out of 41 patients. Of the remaining 14, six were found positive for C. trachomatis and were excluded as they did not return for the follow-up visit, one patient did not achieve complete eradication, one patient infected with both C. trachomatis and U. urealyticum failed to achieve complete eradication, and six patients infected with U. urealyticum failed to be completely cured. No adverse effects were reported in any patient. Single dose administration of 1 g azithromycin appears to be an effective and well-tolerated treatment for chlamydial urethritis and an advantage in terms of patient compliance.     

Alterations in temporal/spatial distribution of GFAP- and vimentin-positive astrocytes after spinal cord contusion with the New York University spinal cord injury device

Astrocytes become reactive as a result of various types of lesions and upregulate 2 intermediate filaments, glial fibrillary acidic protein (GFAP), and the developmentally regulated protein vimentin. Young female Sprague-Dawley rats were subjected to a spinal cord contusion at segment T10 using the New York University injury device. Animals were killed at 1, 2, 7, 14, and 30 days postinjury. Horizontal spinal cord sections spanning segments T7-T13 were assessed with antibodies to both intermediate filament proteins. The number of gray matter GFAP-positive astrocytes increased by 2 days postinjury, with segments adjacent (proximal) to the injury site showing greater responses than areas several segments away (distal). By 30 days following injury, astroglial cell numbers returned to normal levels. Vimentin-positive astrocytes also showed a graded proximal/distal response by 2 days following injury. Proximal regions remained significantly higher at 30 days following injury than control animals. Rostral/caudal changes were also evident, with regions caudal to the injury showing significantly higher numbers of vimentin positive astrocytes than those rostral, indicating that gray matter areas caudal to spinal cord injury may undergo more stress following spinal cord injury.     

Metformin inhibits ganglionic neurotransmission in renal nerves

Intravenous administration of the antihyperglycemic agent metformin decreases arterial pressure and sympathetic nerve activity (SNA). To test the hypothesis that metformin inhibits SNA by interrupting ganglionic neurotransmission, we compared the actions of intravenous administration of metformin and the ganglionic blocker trimethaphan on postganglionic renal and preganglionic adrenal sympathetic nerves in pentobarbital-anesthetized male Sprague-Dawley rats. Intravenous metformin elicited dose-dependent decreases in postganglionic renal SNA (1 mg/kg: 0 +/- 0%; 10 mg/kg: -20 +/- 4%; 100 mg/kg: -92 +/- 3%; n = 7). Conversely, only the maximal dose of metformin affected preganglionic adrenal SNA (100 mg/kg: delta adrenal SNA = -14 +/- 6%; n = 8). Ganglionic blockade with intravenous trimethaphan (5 mg/kg) produced a differential sympathoinhibitory response similar to the response observed after high-dose metformin (delta renal SNA = -100 +/- 3%; delta adrenal SNA = -17 +/- 7%; P < .001). Preganglionic renal neurons were electrically stimulated in the spinal cord, before and during the peak of the sympathoinhibitory response to intravenous metformin, and the magnitude of the stimulus-evoked increases in postganglionic renal SNA were compared. Metformin dose-dependently attenuated the magnitude of the increase in postganglionic renal SNA elicited by stimulation of the spinal cord (30 mg/kg: -23 +/- 8%; 90 mg/kg: -65 +/- 11%; 270 mg/kg: -91 +/- 8%; n = 6 per dose). We conclude that high-dose intravenous metformin interrupts ganglionic neurotransmission in renal nerves.     

Postnatal NGF administration causes adult hyperalgesia and overreactivity to social stimuli but does not reverse capsaicin induced hypoalgesia

The present longitudinal analysis was aimed at assessing (i) the effects of developmental capsaicin (CAPS) administration on nociceptive responsivity and on the response of adult mice to social stimuli; (ii) the action of NGF on the ontogeny of the same nociceptive response and social stimuli; (iii) whether capsaicin treatment could be reversed by subsequent treatment with NGF. CD-1 mouse pups were treated with either capsaicin (50 mg/kg, s.c.) or vehicle on postnatal days (PNDs) 5 and 8. Every other day from PND 9 to PND 21 the same pups received a daily injection of NGF (0.75 mg/kg, s.c.). During both the prepuberal stage (PNDs 14, 21, and 28) and adulthood, mice were repeatedly tested in a hot-plate apparatus (52 +/- 0.1 degrees C for 1 min). At adulthood they also underwent an aggressive behaviour test. NGF-treated mice showed a shorter latency to hindlimb licking response in the hot plate compared to both controls and NGF-CAPS groups. CAPS-treated subjects showed a long-lasting hypoalgesia at both prepuberal and adult stages that was not modified by subsequent NGF treatment. Finally, NGF-treated mice were more aggressive than both controls and CAPS-NGF animals.     

Spontaneous long-term remyelination after traumatic spinal cord injury in rats

The capability of the central nervous system to remyelinate axons after a lesion has been well documented, even though it had been described as an abortive and incomplete process. At present there are no long-term morphometric studies to assess the spinal cord (S.C.) remyelinative capability. With the purpose to understand this phenomenon better, the S.C. of seven lesionless rats and the S.C. of 21 rats subjected to a severe weight-drop contusion injury were evaluated at 1, 2, 4, 6, and 12 months after injury. The axonal diameter and the myelination index (MI = axolemmal perimeter divided by myelinated fiber perimeter) were registered in the outer rim of the cord at T9 SC level using a transmission electron microscope and a digitizing computer system. The average myelinated fiber loss was 95.1%. One month after the SC, 64% of the surviving fibers were demyelinated while 12 months later, only 30% of the fibers had no myelin sheath. The MI in the control group was 0.72 +/- 0.07 (X +/- S.D.). In the experimental groups, the greatest demyelination was observed two months after the lesion (MI = 0.90 +/- 0.03), while the greatest myelination was observed 12 months after the injury (MI = 0.83 +/- 0.02). There was a statistical difference (p < 0.02) in MI between 2 and 12 months which means that remyelination had taken place. Remyelination was mainly achieved because of Schwann cells. The proportion of small fibers (diameter = 0.5 micron or less) considered as axon collaterals, increased from 18.45% at 1 month to 27.66% a year after the contusion. Results suggest that remyelination is not an abortive phenomenon but in fact a slow process occurring parallel to other tissue plastic phenomena, such as the emission of axon collaterals.