Relative effect of surgery and radiotherapy on the internal jugular vein following functional neck dissection

We examined the internal jugular veins in three groups of patients who had undergone (1) a functional neck dissection and radiotherapy, (2) a functional neck dissection alone, or (3) radiotherapy alone, using a noninvasive color Doppler ultrasound scan. The internal jugular veins were ultrasonically bilaterally normal in 18% of patients who had undergone a functional neck dissection and radiotherapy, in 88% of patients who had undergone a functional neck dissection alone, and in 57% of patients who had undergone radiotherapy alone. The combination of a functional neck dissection and radiotherapy significantly affected the internal jugular vein when compared with a functional neck dissection alone.     

Selective inhibition of MAO-A,not MAO-B,results in antidepressant-like effects on DRL 72-s behavior

The effects of monoamine oxidase inhibitors (MAOIs) that selectively inhibit the MAO-A or MAO-B forms of MAO were studied in rats performing under a differential-reinforcement-of-low-rate 72-s (DRL 72-s) schedule of reinforcement. Clorgyline and CGP11305A, irreversible and reversible MAO-A inhibitors, respectively, increased the reinforcement rate, decreased the response rate, and enhanced temporal discrimination. The irreversible MAO-B inhibitor (–)-deprenyl did not produce similar effects. Pargyline did not increase the reinforcement rate at low doses that selectively inhibit MAO-B, but did increase the reinforcement rate at doses that inhibit MAO-A by more than 90%. The present results are in accord with clinical data demonstrating that MAO-A inhibitors are effective therapeutic agents in treating depression while MAO-B inhibitors are of questionable antidepressant efficacy. The present findings provide further evidence that the DRL 72-s schedule may be useful both as a screen for identifying new antidepressants and for investigating the neurochemical effects of antidepressant drugs that are responsible for their therapeutic effects.     

Superior mesenteric artery is more important than inferior mesenteric artery in maintaining colonic mucosal perfusion and integrity in rats

Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO₂). The patterns of ischemia without congestion (IHB, ISO₂) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO₂) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO₂, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.     

Stepwise progression of kindling: Perspectives from the kindling antagonism model

What is the nature of the kindling process? We hypothesize that kindling is a discontinuous process involving discrete, stepwise transitions from one state of neural organization to another. Our data from the kindling antagonism paradigm argue that there are two critical transitions in the kindling process. These transitions constitute major steps in kindled seizure development. They act as "gates" controlling the ability of afterdischarge (AD) activity to effect the necessary reorganization of neural function which drives the kindling process. We identify two critical gates: 1) a forebrain gate which is dependent on norepinephrine (NE) and effects a discrete transition from nonconvulsive, stage 1 and 2 behaviors to stage 3 seizures, and 2) a brainstem gate which is also NE-dependent and effects a transition from stage 3 seizures to stage 4 and 5 seizures. These gates separate the kindling process into 3 "phases" which are different from, but overlap, the traditional behavioral stages of kindling defined by Racine. Current data suggest that these phases involve independent neural circuitry. They may also involve different physiological mechanisms, but this remains to be determined. This hypothesis is designed to provide a framework for the kindling process within which to search for kindling mechanisms.     

Unraveling the mysteries of Duchenne and Becker muscular dystrophy

Through a process that has come to be known as reverse genetics, the gene and gene product involved in Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) have been identified. The DMD/BMD gene is over 2 million base pairs in size and over 50% of DMD/BMD patients harbor submicroscopic deletions for portions of the gene. The gene product, named dystrophin, is 400 Kd in size. Dystrophin is present in skeletal, cardiac, and smooth muscles, as well as brain. The protein is absent or altered in DMD/BMD patient muscle. The normal function of dystrophin and the reasons why its alteration results in the DMD/BMD phenotypes are presently unknown. The discoveries to date, however, provide a starting point for investigating the fundamental pathogenetic mechanisms involved in DMD/BMD.     

Immune activation and oxidative damage in HIV-positive and HIV-negative adolescents

In a cross-sectional study involving subjects from the Reaching for Excellence in Adolescent Health cohort, we examined the associations between HIV status, disease severity, immune activation, and oxidative damage. Subjects (265 HIV-positive and 127 HIV-negative) were young (range: 14-23 years of age) and primarily female (75%) and black (67%). Many subjects, particularly female subjects, were overweight or obese. Relatively few HIV-positive subjects had advanced HIV disease (13%), and 54% were taking antiretroviral therapy (ART). The 2 markers of oxidative damage used in this study (plasma malondialdehyde and protein carbonyl concentrations) did not correlate with each other, and neither was higher in HIV-positive subjects than in HIV-negative controls. Increased oxidative damage was seen in association with male gender, cigarette smoking, marijuana use, immune activation (as indicated by activated CD8 T-cell counts and plasma C-reactive protein concentration), and use of ART, however. Plasma ceruloplasmin was associated with decreased oxidative damage in HIV-positive subjects, although this association was not seen in those taking ART.     

Growth of native Hawaiian school children: I. Research design,stature, and weight measurements

A semilongitudinal survey of the growth of native Hawaiian school children, focused on the development of fatness, has been carried out on the Island of Hawaii. Four cohorts of children, first studied in grades one, four, seven, and ten, were measured annually for four years. Several factors, including percentage of Polynesian ancestry, identification with Hawaiian culture, socioeconomic status, dietary intake, and physical fitness, have been considered for their potential relationship to the development of fatness Data presented here indicate that native Hawaiian boys tend to be taller for their age than NHANES-II medians until age 14 years, but are not significantly taller than their non-Hawaiian classmates. Native Hawaiian boys and girls are heavier for their age than NHANES-II medians at most ages and are significantly heavier than non-Hawaiian classmates. Percentage of Polynesian ancestry is a significant predictor variable of both stature-for-age and weight-for-age among native Hawaiian children in the first and fourth grade cohorts. Study of fatness in a genetically heterogeneous Polynesian population that is relatively homogeneous in regard to modernization may yield insights into genetic contributions to the problem of obesity among Pacific Islanders.     

Pharmacokinetic and experimental data on beta-lactam antibiotics in the treatment of patients

The in vitro and animal model studies on optimal dosage of the newer beta-lactams are summarized and put into historical perspective. They provide a rationale for dosage schedules that continuously maintain inhibitory serum and tissue concentrations throughout the dosage interval. In vitro studies on the post-antibiotic effect (PAE) with beta-lactams revealed only short time periods of post-antibiotic growth suppression with gram-positive cocci and no post-antibiotic effect with gram-negative bacilli. A smilar lack of persistent growth suppression was observed with beta-lactams in a neutropenic mouse thigh infection model for both gram-positive and gram-negative bacteria. In the same animal model, dosing regimens of beta-lactams which continuously provided serum concentrations above the MIC were more efficacious than those that did not. The newer third-generation cephalosporins have prolonged half-lives and can maintain serum levels above the MIC for most pathogens, even when dosed at widely spaced intervals.     

Asthma and the diver

Self-contained underwater breathing apparatus (scuba) diving has grown in popularity, with nearly 9 million sport divers in the United States alone. Approximately 7% of the population has been diagnosed with asthma, which is similar to the percentage of divers admitting they have asthma. Numerous concerns exist regarding subjects with asthma who choose to participate in recreational diving. Among these concerns are pulmonary barotrauma, pneumomediastinum, pneumothorax, arterial gas embolism, ear barotrauma, sinus barotrauma, and dental barotrauma. Despite these concerns, a paucity of information exists linking asthma to increased risk of diving complications. However, it has long been the norm to discourage individuals with asthma from participating in recreational scuba diving. This article examines the currently available literature to allow for a more informed decision regarding the possible risks associated with diving and asthma. It examines the underlying physiological principles associated with diving, including Henry’s law and Boyle’s law, to provide a more intimate understanding on physiological changes occurring in the respiratory system under compressive stress. Finally, this article offers a framework for guiding the patient with asthma who is interested in scuba diving. Under the right circumstances, the patient with asthma can safely participate in recreational diving without apparent increased risk of an asthma-related event.