Simple test to evaluate the risk of urinary calcium stone formation

The pH dependence of the association of apo trp repressor with the series of ligands, tryptophan, tryptamine, indole propionic acid (IPA), and trans-beta-indole acrylic acid (IAA), has been studied using fluorescence titrations and isothermal titration microcalorimetry (ITC). The purpose of such a comparison of ligands and the pH dependency studies is to reveal the role played by the side-chain functional groups in the energetics of the binding of the ligands to the protein. We find that, whereas the binding of tryptamine and IPA have essentially no pH dependence between pH 6 and 10, the binding of tryptophan and IAA depends on pH. For IAA, the affinity drops between pH 6 and 10, consistent with a shift in pKa of some group on the protein from a value of pKa 7.4 to 7.9 upon binding of this ligand. The affinity of IAA also drops below pH 5, but shows saturable binding at pH 2-3, where the protein has previously been found to exist as a partially folded monomeric state. For tryptophan, the pH dependence data indicate that the equilibrium is complicated. We present a model to describe the data in which the alpha-ammonium group of tryptophan has its pKa shifted upward upon binding (i.e. preferential binding of the protonated form of this functional group) and in which the pKa of an unknown group on the protein also has its pKa increased.     

Circadian variations in the risk of urinary calcium oxalate stone formation

OBJECTIVE: To evaluate the circadian fluctuations in the risk of urinary calcium oxalate stone formation with regard to critical periods of crystallization. PATIENTS AND METHODS: Over a given time period, the Tiselius index depends on urine volume and urinary excretion of oxalate, calcium, citrate and magnesium. This crystallization potential was evaluated during three successive periods spread over 24 h for 25 recurrent stone-formers aged 16-76 years (mean 50) and 25 control subjects aged 27-71 years (mean 44). RESULTS: There was no significant difference in the value of the Tiselius index for all equivalent time periods in both groups of patients. The minimum value was recorded in the afternoon and the circadian pattern of the index illustrated the predominant importance of urinary output in its determination. Morning urinary concentrations and excretions of citrate, and nocturnal levels of magnesium were significantly higher in the stone-formers when compared with the control subjects. CONCLUSION: The lithogenic risk for calcium oxalate stones was maximal at the end of the night or during the early morning, when urinary output was minimal. This circadian study revealed abnormalities that are not apparent from non-fractionated 24 h urine samples, and which were potentially relevant to therapy.     

The evaluation of some biochemical parameters in pyridoxine-treated calcium oxalate renal stone formers

20-, 40- and 60-day old chicks were infected with E. tenella (100000 oocysts). The nature of changes in cholesterol, general fat and lecithin of chicks' blood is the same as at the infection with a small dose (5000) of oocysts of E. tenella. Changes in the lipoid components differ only quantitatively: they are greater at the infection with a greater dose of oocysts that at the infection with a small one.     

Effect of oral calcium loading on intact PTH and calcitriol in idiopathic renal calcium stone formers and healthy controls

The calciuric response after an oral calcium load (1000 mg elemental calcium together with a standard breakfast) was studied in 13 healthy male controls and 21 recurrent idiopathic renal calcium stone formers, 12 with hypercalciuria (UCa x V > 7.50 mmol/24 h) and nine with normocalciuria. In controls, serum 1,25(OH)2 vitamin D3 (calcitriol) remained unchanged 6 h after oral calcium load (50.6 +/- 5.1 versus 50.9 +/- 5.0 pg/ml), whereas it tended to increase in hypercalciuric (from 53.6 +/- 3.2 to 60.6 +/- 5.4 pg/ml, P = 0.182) and fell in normocalciuric stone formers (from 45.9 +/- 2.6 to 38.1 +/- 3.3 pg/ml, P = 0.011). The total amount of urinary calcium excreted after OCL was 2.50 +/- 0.20 mmol in controls, 2.27 +/- 0.27 mmol in normocalciuric and 3.62 +/- 0.32 mmol in hypercalciuric stone formers (P = 0.005 versus controls and normocalciuric stone formers respectively); it positively correlated with serum calcitriol 6 h after calcium load (r = 0.392, P = 0.024). Maximum increase in urinary calcium excretion rate, delta Ca-Emax, was inversely related to intact PTH levels in the first 4 h after calcium load, i.e. more pronounced PTH suppression predicted a steeper increase in urinary calcium excretion rate. Twenty-four-hour urine calcium excretion rate was inversely related to the ratio of delta calcitriol/deltaPTHmax after calcium load (r = -0.653, P = 0.0001), indicating that an abnormally up-regulated synthesis of calcitriol and consecutive relative PTH suppression induce hypercalciuria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lipid changes in hepatic microsomes and its relationship to P-nitrophenol glucuronidation in an experimental model of portal hypertension

The liver is responsible for the most important metabolic pathway of non polar compounds. The aim of the present work was to study the p-nitrophenol glucuronidation and its relationship with lipidic composition of microsomal membrane in a model of hepatic portal hypertension and hepatocellular damage induced by monocrotaline. A global increment in liver microsomal phospholipids as well as changes in the phospholipid pattern (phosphatidylethanolamine and sphingomyelin increased up to 156 +/- 13 and 195 +/- 14% respectively) were detected in monocrotaline intoxicated rats when it were compared to control rats. The microsomal cholesterol content showed a decrease in monocrotaline intoxicated rats. (4.1 +/- 0.7 against 6.6 +/- 1.5 micrograms/mg of microsomal protein, in control rats). When p-nitrophenol activity was measured, Km from monocrotaline intoxicated rats was 0.137 mM, and Vmax was 2.9 nmol of p-nitrophenol/mg microsomal protein since in control group Km was 0.322 mM, and Vmax was 4.5 nmol of p-nitrophenol/mg microsomal protein. It is concluded that monocrotaline intoxicated rats showed a different behavior in the kinetics of p-nitrophenol UDP-glucuronyltransferase, as well as a different microsomal lipidic profile, when compared to control group.     

Kidney morphological changes in relation to long-term renal function and metabolic control in adolescents with IDDM

OBJECTIVE: To investigate the impact of HIV infection on the prevalence, incidence and short-term prognosis of squamous intraepithelial lesions (SIL), in a prospective study with 1-year follow-up. METHODS: Between 1993 and 1995, 271 HIV-positive and 171 HIV-negative women at high risk of HIV infection were recruited, 365 (82.6%) of whom completed the 1-year follow-up. The women underwent a Papanicolaou smear test at inclusion and at 6 and 12 months. Human papillomavirus (HPV) was detected at inclusion by Southern blot and PCR. RESULTS: The SIL prevalence ranged from 7.5% for HIV-negative to 31.3% for HIV-positive women with CD4 cell counts < 500 x 10(6)/l (P < 0.001). Other factors associated independently and significantly with SIL prevalence were HPV-16, 18, 33 and related types, HPV-31, -35, -39 and related types, lifetime number of partners, younger age, past history of SIL and lack of past cervical screening. The SIL incidence ranged from 4.9% in HIV-negative women to 27% in HIV-positive women with CD4 cells < 500 x 10(6)/l (P < 0.001). Progression from low- to high-grade SIL during follow-up was detected in 38.1% of HIV-positive women with CD4 cells < or = 500 x 10(6)/l but in no HIV-negative nor HIV-positive women with CD4 cells > 500 x 10(6)/l. HPV-16, 18, 33 and related types were also associated with higher incidence of SIL and progression from low- to high-grade SIL. CONCLUSION: HIV-induced immunodeficiency is associated with high prevalence, incidence and persistence/progression of SIL. A pejorative influence of HIV infection without marked immunodeficiency is less clear. HIV-positive women with SIL may thus benefit from early treatment when a useful immune response is still present.     

Clinical observations of metabolic changes occurring in renal transplant recipients receiving ketoconazole

Metabolism of cyclosporine is reduced by ketoconazole binding to the monooxygenase responsible for cyclosporine degradation. This isozyme of cytochrome P450, along with other similar monooxygenases, is involved in the regulation of the synthesis and degradation of important metabolic pathways of cholesterol. Monooxygenases throughout these pathways are inhibited by ketoconazole binding causing a decreased metabolism of calcitriol, bile acids, and steroid hormones, and can thereby potentiate altered lipid metabolism, bone metabolism, and weight status of transplant recipients. A group of renal transplant recipients taking ketoconazole (n=25) was compared with a matched cohort not receiving ketoconazole for metabolic changes during the first six months posttransplantation. Lower LDL cholesterol levels were seen in the ketoconazole group (109 +/- 8 mg/dl) than the no ketoconazole group (140 +/- 8 mg/dl) at one month but this difference was not sustained at six months. More bone loss occurred in the ketoconazole group as demonstrated by significant changes in bone density as well as a greater urinary appearance of bone collagen crosslink, deoxy-pyridinoline (29 +/- 4 nmol dpd/mmol creatinine and 18 +/- 4 at six months for the ketoconazole group versus the no ketoconazole group, respectively, P<0.05). Weight gain changes were different between the ketoconazole group and no ketoconazole group (6.4 +/- 1.4 kg versus 5.0 +/- 1.3 kg) at six months and an increased rate of weight gain over time in the ketoconazole group (0.02 kg/day at one month versus 0.05 kg/day at six months, P<0.007). Effectiveness of ketoconazole inhibition of cyclosporine is valuable, but inhibition of other metabolic pathways should be evaluated as well.     

Acetabular changes in an experimental model of developmental dysplasia of the hip (DDH)

We wished to correlate the morphological acetabular changes in developmental dysplasia of the hip (DDH) with changes at the tissue level. A secondary aim was to develop a way of measuring the dysplastic acetabulum. We studied the changes in rabbit acetabula after maintaining knee extension, measuring the major diameter from the acetabular notch to the farthest opposite point on the acetabular margin. The minor diameter was at right angles to this. The dysplastic acetabula showed elongation along the major diameter compared to control hips. Microscopic sections were made along major and minor diameters. The posterosuperior lip of the dysplastic acetabulum showed an early eversion of the acetabular cartilage. Growth of the articular cartilage in this new direction accounted for the acetabular elongation. As well as providing insight into the manner of acetabular shape change, the findings suggest the nature of remodeling required before normal acetabular growth can resume during treatment.     

Effect of vitamin E and mannitol on renal calcium oxalate retention in experimental nephrolithiasis

STUDY OBJECTIVE: To assess the efficacy of laser laparoscopic photocoagulation of endometriomas (2-18 cm) in patients with pain, infertility, or a combination of the two. DESIGN: Retrospective review of all patients with endometriomas from June 1, 1983, to December 31, 1993. SETTING: Department of gynecology and obstetrics at a district general hospital and national training center in minimal access surgery. PATIENTS: One hundred sixty-five women with large endometriomas present at the time of laser laparoscopy. INTERVENTIONS: Carbon dioxide laser or potassium-titanyl-phosphate laser laparoscopic surgery. MEASUREMENTS AND MAIN RESULTS: Ninety (74%) of 122 patients reported improvement or resolution of pain; and 30 of 66 achieved a pregnancy, for a cumulative conception rate of 45%. CONCLUSION: Laser laparoscopy is a practical, safe, and effective technique for the management of large ovarian endometriomas.     

Effect of cytomegalovirus on an experimental model of chronic renal allograft rejection under triple-drug treatment in the rat

BACKGROUND: Cytomegalovirus (CMV) infection is thought to be a risk factor of chronic rejection. In clinical studies and animal models, mainly concerning graft vasculopathy, CMV has been demonstrated to enhance allograft arteriosclerosis. In this study we have investigated the effect of CMV on the early inflammatory response and graft histology in an experimental model of renal transplantation in a rat strain combination that develops chronic rejection under triple-drug immunosuppression. METHODS: Renal transplantations were performed in a rat strain combination of DA-->BN receiving triple-drug treatment (2 mg/kg methylprednisolone, 2 mg/kg azathioprine, 5 mg/kg cyclosporine daily subcutaneously). One group of immunosuppressed animals was infected with rat CMV, the Maastricht strain (10(5) plaque-forming units intraperitoneally), and the other group was left uninfected. As a positive control for alloresponse, one group of recipients received neither immunosuppression nor virus. Syngenic transplantations with triple-drug treatment and CMV were used as negative controls. The grafts were monitored by frequent ultrasound-guided fine-needle aspiration biopsies, and the intragraft inflammation was quantified in detail by the increment method and expressed in corrected increment units (CIU). Graft histology was performed in parallel. RESULTS: Nonimmunosuppressed animals developed acute rejection with a high peak of inflammation (7.9+/-3.2 CIU), a typical blast response, and lymphocytosis followed by infiltration of macrophages and necrosis within 7 days. Triple drug-treated animals had a short, mild inflammatory response (3.3+/-1.4 CIU at the peak) in the graft 3-5 days after transplantation but ended up with histological changes characteristic of chronic rejection with vasculopathy and fibrosis 40-60 days later. Triple drug-treated animals with CMV demonstrated a significantly stronger inflammation (4.5+/-1.8 CIU, P<0.01) than those without, and lymphoid activation continued longer and was followed by infiltration of macrophages in the graft. CMV infection of the graft was demonstrated by viral culture and antigen detection. In histology, chronic rejection with intimal thickening of arteries and arterioles and medial necrosis of large arteries was seen at 14 days, ending up with remarkable graft fibrosis within 20 days after transplantation. CONCLUSION: CMV prolonged and increased graft inflammation and accelerated chronic rejection of renal allografts under triple-drug treatment.     

The qualification of different free muscle transplants to reconstruct mimic function: an experimental study in rabbits

With the scutuloauricularis muscle, we developed a new model for experimental free transplantation of mimic muscles in the rabbit and studied the qualification of different muscles for free functional grafting into the position of the facial muscle, which is to be replaced. Forty adult female white New Zealand rabbits were distributed to four groups of 10 rabbits each. In group 1, the operative techniques of the new transplantation models were developed in the scutuloauricularis muscle, the pectoralis descendens muscle, and a comparable part of the rectus femoris muscle. In group 2, the scutuloauricularis muscle was transplanted orthotopically with microneurovascular anastomoses on the left side; in group 3, the pectoralis descendens muscle was transplanted into the position of the scutuloauricularis after its removal; and with the animals in group 4, a piece of the rectus femoris muscle was transplanted into the position of the mimic muscle after its removal. In all muscle transplants, the neurovascular supply was reestablished microsurgically by end-to-end anastomoses to the superficial temporal vessels and direct nerve coaptation to the facial nerve branches supplying originally the scutuloauricularis muscle. Nine months after transplantation, force measurements were performed in all transplanted muscles and the scutuloauricularis muscles of the control side. Cross-sections stained for ATPase after alkaline preincubation at pH 10.4 were used for computer-assisted planimetry of the muscle fibers. The orthotopically transplanted scutuloauricularis muscles reached with 2.84 (+/-1.04) N for maximal tetanic tension on the average 87.7 (+/-32.1) percent of that of the control scutuloauricularis muscles, the pectoralis descendens muscles with 4.25 (+/-2.15) N on the average 188.7 (+/-100.7) percent of that of the controls, and the pieces of rectus femoris muscles 6.62 (+/-2.16) N or 185.3 (+/-45.4) percent of that of the controls. All three muscles were identified as fast contracting muscles before and after transplantation. By transplantation, the content of type II muscle fibers changed from 58.2 to 68.0 percent in the scutuloauricularis muscle, from 62.4 to 74.4 percent in the musculus pectoralis descendens, and from 92.5 to 82.8 percent in the rectus femoris muscle. For the first time, an experimental model for free transplantation of mimic muscles was developed and functionally assessed. The most important result of this study was the fact that the double-sized muscle grafts developed twice the force of the control scutuloauricularis muscles, although reinnervated by the original muscle nerve branch. This result underlines the usefulness of overdimensioning during clinical muscle transplantation. It was also shown that parts of big muscles can be grafted with results similar to those experienced with complete smaller muscles.     

Bacterial renal infection in rats produced by direct injection of bacteria into renal tissue--an experimental model

A new method for producing an experimental model of renal infection in rats is described. It is based on a direct injection of a concentrated E. coli suspension either into both kidneys or only one of them. The method is simple and takes little time; the mortality of experimental animals is low. A focal acute purulent renal inflammation is elicited which tends to propagate towards the papilla. A significant renal infection persists at least over six weeks. The renal infection model is suitable for testing the antibacterial activities of drugs, as documented by the results of a therapeutical experiment with gentamicin and other agents.     

Ultrastructural changes in the interstitial cells of the kidney medullary substance in suckling rabbits with experimental cholera

A culture of virulent selection of cholera vibrios L-top 5879 was introduced through the probe to suckling rabbits-pups 10 to 12 days old. Ultrastructural changes of interstitial cells and capillaries of kidney medulla were studied. During vibrio adhesion (4 hrs after the inaction) interstitial cells acquire dystrophic changes, lipid granules content reduces, while vascular permeability grows higher which suggests the presence of prostaglandin precursors elimination into blood flow. Cholera development (1-2 days later) is accompanied with progressing of signs of prostaglandin synthesis activation and their precursors passage into the vascular bed.     

Characterization of estrogenicity of phytoestrogens in an endometrial-derived experimental model

OBJECTIVE: To evaluate field neurosurgery supporting VII Corps during combat in Operation Desert Storm. RESULTS: (1) Only 1 of 22 patients who had a head wound died. (2) The one computed tomography unit in a forward hospital worked well, aiding diagnosis and surgical management. The occurrence of hematoma at a distance from the missile track has been worrisome to past field neurosurgeons, but none of 9 patients who had predebridement scans had a distant clot. (3) The number of brain wounds was fewer than expected for Americans, and the wounds were basilar in location. Iraqis, by contrast, had wounds that were randomly distributed about the head. CONCLUSIONS: (1) Although computed tomography is a useful diagnostic adjunct, its availability should not be a sine qua non for forward neurosurgery. (2) The current Kevlar helmet design appears successful.     

Renal perfusion pressure is an important determinant of sodium and calcium excretion in DOC-salt hypertension

This study tested the hypothesis that the increased renal perfusion pressure in DOC-salt hypertension is essential for the maintenance of sodium balance and is responsible for the hypercalciuria associated with this model. Twelve chronically instrumented dogs were placed on a high salt intake and mean arterial pressure (MAP) was measured 24 h/day. After a control period, a 17-day DOC infusion period was begun. In six dogs, however, renal perfusion pressure (RPP) to both kidneys was maintained at control levels for the first 12 days of the DOC infusion by the continuous, servo-controlled adjustment of a suprarenal silastic occluder on the abdominal aorta. The servo-controlled dogs had significantly more sodium retention and a greater increase in blood pressure than the six control DOC hypertensive dogs. Urinary calcium excretion in the control dogs began to increase from 24 +/- 6 mg/day on day 1 of DOC, and increased progressively to 100 +/- 14 and 175 +/- 30 mg/day by days 7 and 12, respectively. Plasma ionized calcium decreased, and parathyroid hormone (PTH) (1-84) increased, significantly by day 4. The hypercalciuria was not different in the servo-controlled dogs for the first 7 days of DOC, but was attenuated thereafter. Thus, increased RPP is important in restoring sodium balance and in maintaining the calciuresis in DOC-salt hypertension; however, other mechanisms also are important, particularly during the onset of hypertension.     

Tissue-specific galactosyltransferase abnormalities in an experimental model of rheumatoid arthritis

The aim of our study was to determine whether the minor polar components of virgin olive oil could have favorable effects (1) on fasting and postprandial lipid profile and (2) on low-density lipoprotein (LDL) composition and susceptibility to oxidation in vitro. Ten normolipidic subjects were included in a crossover study (two diet periods of 3 weeks) and received either virgin olive oil (OO diet) or oleic acid rich sunflower oil. An oral fat load was performed at the end of each period. The plasma lipid levels were not significantly different after both diets in the fasting and postprandial states. A few minor variations of the LDL composition were observed only in the postprandial lipemia, and they were different after both diets. The LDL oxidation susceptibility was evaluated by the formation of conjugated dienes. With LDL isolated in the fasting state, the diene production decreased (p = 0.0573) only after the OO diet. The dienes determined at time 0 and the maximal dienes obtained during the oxidation reaction decreased (p = 0.0145 and p = 0.0184, respectively) only after the OO fat load. Nevertheless, the diene production decrease was not significant (p = 0.0848). Our results suggest a mild effect of minor components of virgin olive oil related to a decrease of LDL susceptibility to oxidation; further analyses are necessary to give clear conclusions about their role.     

Effect of experimental diabetes mellitus on gentamicin-induced acute renal functional changes in the anaesthetized rat

1. Rats with streptozotocin (STZ) diabetes are protected from gentamicin (GEN) nephrotoxicity. Because the chronic renal damage from GEN is preceded by acute renal functional changes (notably hypercalciuria), the present study aims to determine whether diabetes may also protect against the acute effects of the drug. If there is a link between the rapid physiological actions of GEN and its subsequent nephrotoxicity, the former may also be affected by the diabetic condition. 2. Standard renal clearance techniques were performed on anaesthetized rats that had been injected with STZ or vehicle 2 weeks previously. All animals were infused with 0.9% NaCl for 5 h and then either GEN (0.28 mg/kg per min) or 0.9% NaCl alone for 2 h. 3. Baseline fractional calcium excretion (FE(Ca)) of diabetic rats was three-fold that of control animals (6.6+/-0.2 vs 2.2+/-0.2%, respectively; P<0.01, MANOVA). Following GEN infusion, a comparable increase in FE(Ca) occurred in control and diabetic rats (5.3+/-0.6 vs 5.3+/-0.8%, respectively; NS). 4. Streptozotocin diabetes, therefore, does not alter the acute hypercalciuric response to GEN. This may suggest that the acute effects of GEN on renal calcium handling do not contribute to the subsequent nephrotoxicity. However, the higher baseline FE(Ca) seen in diabetic rats may afford protection against the renal injury caused by gentamicin.     

Development of an experimental model of Microsporum canis infection in cats

An experimental infection model was developed for reliable induction of Microsporum canis skin infections in cats, using a defined number of macroconidia harvested from the fungus in culture. The strain of M. canis used produced highly fluorescent hairs under ultraviolet illumination. Kittens 8 to 9 weeks of age (n = 6) received 10(5) macroconidia applied topically to a closely-shaved area of skin. Sites were dressed with an occlusive bandage for 3 days, then grooming was restricted for an additional 4 weeks. Lesions were first observed 2 weeks after inoculation, enlarged over the following 6 to 8 weeks, then decreased in size and appeared healed at 12 to 14 weeks after inoculation. Cats often developed satellite lesions on the face, ears, or other body regions. The experimental infections strongly resembled moderately severe cases of naturally-occurring feline dermatophytosis in clinical patients. This experimental infection model will be useful for evaluation of topical and systemic treatments for feline M. canis infection.     

Development of an experimental rat model of intraabdominal abscess by Escherichia coli alone. I. Materials for abscess formation

To develop a new animal model of intraabdominal abscess by Escherichia coli alone, we reevaluated anaerobes and other additions which had been believed necessary to produce an intraabdominal abscess. We took the method of bacterial implantation by insertion of a double gelatin capsules containing microbes and the additions into the peritoneal cavity of male Wister rats. We examined the requirement of causative bacteria for an abscess including both aerobes and anaerobes, sterilized feces, and barium sulfate. It has been proven that a simple and well reproducible intraabdominal abscess can be developed without fail at the seventh day after inoculation although anaerobic bacteria, sterilized feces, and barium sulfate are not used. However, we have failed to produce an abscess without sterilized gauze fiber which should be a core of an abscess and is used instead of sterilized feces. This animal model will contribute to a major simplification of the original one heretofore in use, and is expected to serve as an aid to elucidate the mechanisms of abscess formation.