The loss of heterozygosity in retinoblastoma and p53 suppressor genes as a prognostic indicator for head and neck cancer

Inactivation of tumor suppressor genes, including p53 and retinoblastoma (Rb), are commonly found in all cancers, including head and neck squamous cell carcinoma. Alterations at either p53 or Rb, however, are only weakly associated with tumor aggressiveness. In many cancers loss of heterozygosity (LOH) at multiple loci is associated with decreased survival. The polymerase chain reaction and highly informative microsatellite markers were used to compare DNA from matched sets of 63 head and neck squamous cell cancers and normal tissue for LOH at the p53 and Rb loci. At p53, 50 were informative, with LOH occurring in 19 (38%). Of the 57 that were informative at Rb, LOH occurred in 21 (37%). Of the 46 that were informative at both p53 and Rb, LOH occurred in 10 (22%) at both loci. When LOH for p53 and Rb individually was compared to stage, differentiation, and survival, there was no correlation. However, the patients with LOH at both loci had a significantly poorer survival (P = .009). This strongly supports the contention that simultaneous alterations of these two tumor suppressor genes favor tumor aggressiveness and can be used as a prognostic indicator.     

Stress-induced subsensitivity to catecholamines depends on the estrous cycle

In this article we compare how sensitivity to the chronotropic effect of noradrenaline and adrenaline of right atria isolated from female rats is modified after repeated swimming or foot-shock stress, under the influence of the estrous cycle. Right atria from stressed female rats sacrificed at diestrus were subsensitive to both catecholamines, irrespective of the stressor agent. However, although subsensitivity to noradrenaline was of similar intensity, subsensitivity to adrenaline was more pronounced in right atria from foot shock stressed rats as opposed to swimming-stressed rats. Identical stress protocols did not induce any alteration in atrial sensitivity to catecholamines when the stressed female rats were sacrificed at estrus. We conclude that the stress reaction concerning the mediation of cardiac chronotropism by catecholamines is related to the severity of the stressor agent and is strongly influenced by the estrous cycle.     

Solution structure of the minor conformer of a DNA duplex containing a dG mismatch opposite a benzo[a]pyrene diol epoxide/dA adduct: glycosidic rotation from syn to anti at the modified deoxyadenosine

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants whose metabolism in mammals results in deleterious cell transformation. Covalent modification of DNA by diol epoxides metabolically formed from PAHs such a benzo[a]pyrene (BaP) provides a mechanism for the genotoxicity, mutagenicity, and carcinogenicity of PAHs. We had previously reported NMR evidence for a minor conformer of the duplex d(G1G2T3C4A5*C6G7A8G9).d(C10T11C12G13G14G15A16C17C18) containing a dG14 mismatch opposite a dA5* residue modified at the exocyclic amino group by trans addition to (+)-(7R,8S,9S,10R)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a] pyrene [Yeh, H.J.C., Sayer, J.M., Liu, X., Altieri, A.S., Byrd, R.A., Lashman, M.K., Yagi, H., Schurer, E.J., Gorenstein, D.G., & Jerina, D.M. (1995) Biochemistry 34, 13570-13581]. In the present work, we describe the structure of this minor conformer (ca. 17% of the total conformer population). This represents the first structural determination of a minor conformer of a carcinogen-lesion DNA adduct. Two-dimensional NOESY, ROESY, TOCSY, and exchange-only spectra at 750 MHz allowed nearly complete sequential assignment of both conformers. In the minor conformer, the adducted base assumes an anti-glycosidic torsion angle whereas in the major conformer it assumes an unusual syn-glycosidic torsion angle. The aromatic hydrocarbon in the minor conformer is intercalated between dG13 and dG14, preserving the energetically favorable stacking interactions found in the major conformer. The major structural differences between the two conformers appear to be near the lesion site as evidenced by the large chemical shift differences between major and minor conformer protons near the lesion site; away from this site, the chemical shifts of the major and minor conformer protons are nearly identical. Because any of the conformations of benzo[a]pyrene diol epoxide-modified DNA may contribute to tumorigenic activity, structural determination of all conformations is essential for the elucidation of the mechanism of cell transformation initiated by covalent modification of DNA by PAHs.     

In vivo activities of ceftriaxone and vancomycin against Borrelia spp. in the mouse brain and other sites

Borrelia burgdorferi, the agent of Lyme disease, and B. turicatae, a neurotropic agent of relapsing fever, are susceptible to vancomycin in vitro, with an MIC of 0.5 microgram/ml. To determine the activity of vancomycin in vivo, particularly in the brain, we infected adult immunocompetent BALB/c and immunodeficient CB-17 scid mice with B. burgdorferi or B. turicatae. The mice were then treated with vancomycin, ceftriaxone as a positive control, or normal saline as a negative control. The effectiveness of treatment was assessed by cultures of blood and brain and other tissues. Ceftriaxone at a dose of 25 mg/kg of body weight administered every 12 h for 7 to 10 days eliminated cultivable B. burgdorferi or B. turicatae from all BALB/c or scid mice in the study. Vancomycin at 30 mg/kg administered every 12 h was effective in eliminating infection from immunodeficient mice if treatment was started within 3 days of the onset of infection. If treatment with vancomycin was delayed for 7 days or more, vancomycin failed to eradicate infection with B. burgdorferi or B. turicatae from immunodeficient mice. The failure of vancomycin in eradicating established infections in immunodeficient mice was associated with the persistence of viable spirochetes in the brain during antibiotic treatment.     

Differential regulation of GABA(A) receptor gene expression by ethanol in the rat hippocampus versus cerebral cortex

Previous research has shown that chronic ethanol consumption dramatically alters GABA(A) receptor alpha1 and alpha4 subunit gene expression in the cerebral cortex and GABA(A) receptor alpha1 and alpha6 subunit gene expression in the cerebellum. However, it is not yet known if chronic ethanol consumption produces similar alterations in GABA(A) receptor gene expression in other brain regions. One brain region of interest is the hippocampus because it has recently been shown that a subset of GABA(A) receptors in the hippocampus is responsive to pharmacologically relevant concentrations of ethanol. Therefore, we directly compared the effects of chronic ethanol consumption on GABA(A) receptor subunit gene expression in the hippocampus and cerebral cortex. Furthermore, we investigated whether the duration of ethanol consumption (14 or 40 days) would influence regulation of GABA(A) receptor gene expression in these two brain regions. Chronic ethanol consumption produced a significant increase in the level of GABA(A) receptor alpha4 subunit peptide in the hippocampus following 40 days but not 14 days. The relative expression of hippocampal GABA(A) receptor alpha1, alpha2, alpha3, beta(2/3), or gamma2 was not altered by either period of chronic ethanol exposure. In marked contrast, chronic ethanol consumption for 40 days significantly increased the relative expression of cerebral cortical GABA(A) receptor alpha4 subunits and significantly decreased the relative expression of cerebral cortical GABA(A) receptor alpha1 subunits. This finding is consistent with previous results following 14 days of chronic ethanol consumption. Hence, chronic ethanol consumption alters GABA(A) receptor gene expression in the hippocampus but in a different manner from that in either the cerebral cortex or the cerebellum. Furthermore, these alterations are dependent on the duration of ethanol exposure.     

Binding and transcytosis of botulinum neurotoxin by polarized human colon carcinoma cells

T-84 and Caco-2 human colon carcinoma cells and Madin-Darby canine kidney (MDCK) cells were used to study binding and transcytosis of iodinated Clostridium botulinum neurotoxin serotypes A, B, and C, as well as tetanus toxin. Specific binding and transcytosis were demonstrated for serotypes A and B in intestinal cells. Using serotype A as an example, the rate of transcytosis by T-84 cells was determined in both apical to basolateral (11.34 fmol/h/cm2) as well as basolateral to apical (8.98 fmol/h/cm2) directions, and by Caco-2 cells in the apical to basolateral (8.42 fmol/h/cm2) direction. Serotype A retained intact di-chain structure during transit through T-84 or Caco-2 cells, and when released on the basolateral side was toxic in vivo to mice and in vitro on mouse phrenic nerve-hemidiaphragm preparations. Serotype C and tetanus toxin did not bind effectively to T-84 cells, nor were they efficiently transcytosed (8-10% of serotype A). MDCK cells did not bind or efficiently transcytose (0.32 fmol/h/cm2) botulinum toxin. Further characterization demonstrated that the rate of transcytosis for serotype A in T-84 cells was increased 66% when vesicle sorting was disrupted by 5 microM brefeldin A, decreased 42% when microtubules were disrupted by 10 microM nocodazole, and decreased 74% at 18 degreesC. Drugs that antagonize toxin action at the nerve terminal, such as bafilomycin A1 (which prevents acidification of endosomes) and methylamine HCl (which neutralizes acidification of endosomes), produced only a modest inhibitory effect on the rate of transcytosis (17-22%). These results may provide an explanation for the mechanism by which botulinum toxin escapes the human gastrointestinal tract, and they may also explain why specific serotypes cause human disease and others do not.     

Safety and cost-effectiveness of outpatient total body irradiation in pediatric patients undergoing stem cell transplantation

Political changes in Poland in 1989 initiated a transition period for country's economy into a free market. This new situation prompted the pharmaceutical sector to apply for marketing authorization of a huge number of drugs. Subsequently, the availability, supply and variety of drugs was changing to resemble the one existing on the European Union market. We have analyzed the pattern of adverse drug reactions reported in Poland during the past 10 years. Subsequently we compared our data for years 1991-1995 with the reports received by the Belgian National Center for Monitoring of Adverse Drug Reactions over period 1990-1994. It was found that the number of reports increased in parallel with the number of drugs available. Also the variety of reported reactions was greater. Spontaneous reporting by individual physicians increased and the number of reports from the pharmaceutical inspection diminished. Comparison with the patterns of reporting in Belgium showed the range of drugs included in the reports to be similar in both countries during the studied period. In conclusion: we found that the increase in range and availability of drugs changed substantially the patterns of reporting of adverse drug reactions in Poland. It became similar to that observed in EU countries.     

Phasic firing time locked to cocaine self-infusion and locomotion: dissociable firing patterns of single nucleus accumbens neurons in the rat

The activity of single nucleus accumbens (NAcc) neurons of rats was extracellularly recorded during intravenous cocaine self-administration sessions (0.7 mg/kg per infusion, fixed ratio 1). We reported previously that NAcc neurons showed a change, usually a decrease, in firing rate during the first 1 min after the cocaine-reinforced lever press. This postpress change was followed by a progressive reversal of that change, which began within the first 2 min after the press and was not complete until the last 1 min before the next lever press (termed the change + progressive reversal firing pattern). In the present study we documented a regular pattern of locomotion that occurred in parallel with the change + progressive reversal firing pattern. This observation suggested that discharges time locked to locomotion may determine the change + progressive reversal firing pattern. However, 55% of the neurons failed to show firing time locked to locomotion that could have contributed to the change + progressive reversal firing pattern. Moreover, for all neurons, the change + progressive reversal firing pattern was apparent even if the calculation of firing rate excluded all periods of locomotion. The present data showed that the change + progressive reversal firing pattern is not solely attributable to phasic changes in firing time locked to the execution of locomotion. The change + progressive reversal firing pattern closely mirrors changes in drug level and dopamine overflow observed by previous researchers and may thus be a component of the neurophysiological mechanism by which drug level regulates drug-taking behavior during an ongoing self-administration session.     

Obstructed labor injury complex: obstetric fistula formation and the multifaceted morbidity of maternal birth trauma in the developing world

Prolonged obstructed labor may produce injuries to multiple organ systems. The best known, and most common, of these injuries is obstetric fistula formation. When obstructed labor is unrelieved, the presenting fetal part is impacted against the soft tissues of the pelvis and a widespread ischemic vascular injury develops that results in tissue necrosis and subsequent fistula formation. Unlike the postsurgical vesicovaginal fistula, however, which is usually the result of focal trauma to otherwise healthy tissues, the obstetric fistula is the result of a "field injury" to a broad area. The field injury that is produced by prolonged obstructed labor may result in multiple birth-related injuries in addition to (or instead of) a vesicovaginal fistula. Focusing simply on the "hole" between the bladder and the vagina ignores the multifaceted nature of the injury that many of these patients have sustained. These injuries may include total urethral loss, stress incontinence, hydroureteronephrosis, renal failure, rectovaginal fistula formation, rectal atresia, anal sphincter incompetence, cervical destruction, amenorrhea, pelvic inflammatory disease, secondary infertility, vaginal stenosis, osteitis pubis, and foot-drop. In addition to their physical injuries, women who have experienced prolonged obstructed labor often develop serious social problems, including divorce, exclusion from religious activities, separation from their families, worsening poverty, malnutrition, and almost unendurable suffering. Isolated almost exclusively to the developing world, particularly Africa, this problem has not received the international attention that it deserves, from either a medical or a social standpoint.