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.     

Dose response, coasting, and differential fiber vulnerability in human toxic neuropathy: a prospective study of pyridoxine neurotoxicity.

We administered either 1 or 3 g/d of pyridoxine (vitamin B6) to five healthy volunteers and repeatedly followed serum pyridoxal phosphate levels, clinical symptoms and signs, quantitative sensory thresholds (QSTs), and sural nerve electrophysiology. Pyridoxine was discontinued at the first sign of either clinical or laboratory abnormality. In all subjects, sensory symptoms and QST abnormalities occurred concurrently. Subjects receiving higher doses became symptomatic earlier than low-dose subjects. Elevation of thermal QSTs preceded or exceeded that for vibration in the three low-dose subjects; vibration and thermal QST became abnormal simultaneously in the higher-dose subjects. A reduction in the amplitude of the sural sensory potential lagged behind QST changes in two of three subjects. Symptoms continued to progress ("coasting") for 2 to 3 weeks despite stopping pyridoxine administration and the return of serum pyridoxal phosphate levels to normal. This study suggests that (1) there is a clear dose-percent relationship for pyridoxine-induced neuropathy, (2) QST is a sensitive measurement for detecting early peripheral neuropathy; QST abnormalities may precede changes in nerve conduction studies, (3) coasting appears unrelated to persistently elevated blood levels of the toxin, and (4) a dose-dependent vulnerability may exist among nerve fibers of different caliber when exposed to an axonal toxin, such as pyridoxine.     

The role of atmospheric pressure variation in the development of spontaneous pneumothoraces

It has been postulated that spontaneous pneumothoraces (SP) develop because of rupture of subpleural blebs, and that atmospheric pressure changes (delta AP) may be contributory. A 5-year retrospective analysis of SP admissions was carried out to determine if delta AP do play a role in SP development. Using a 36-yr record of hourly delta AP, a normative background for delta AP was constructed. A fall in AP below the fifth, or a rise above the ninety-fifth percentile during these time periods, was classed as "unusual." Atmospheric pressure changes in the 4 days prior to SP were analyzed. The expected frequency of SP occurring by chance, if no relationship to delta AP existed, was also calculated. A total of 192 cases of SP was analyzed. Traumatic pneumothoraces were excluded. The majority of cases (72%) had been exposed to at least one "unusual" delta AP in the 4 days prior to onset of symptoms. Among those with four or more "unusual" exposures, SP occurrence was significantly more frequent than expected by chance alone (p less than 10(-10]. A strong positive association between delta AP and SP was not found in all cases, as delta AP are unlikely to be the only causative factor for SP. This finding of a relationship with ambient pressure changes lends support to the theory that SP develop as a result of rupture of subpleural blebs.     

Studies of the mechanism of tolerance induced by short-term immunosuppression with cyclosporine in high-risk corneal allograft recipients. I. Analysis of CTL precursor frequencies

Transplantation of unmatched allogeneic corneas into highly vascularized recipient eyes under the cover of short-term immunosuppression with cyclosporine enables permanent engraftment. The aim of this study was to further elucidate the mechanism(s) underlying this tolerant state. In eight "high-risk" cornea recipients the clone sizes of donor-specific and third-party reactive cytotoxic T cell precursors were assessed by limiting dilution analyses before and at three and six months after transplantation. Acquired allograft tolerance in these patients was not accompanied by clonal reduction of donor-specific CTL-p, whereas in the case of an irreversible rejection the donor-specific CTL pool size was significantly enlarged. This donor-specific CTL-p increase could already be seen two months before clinical manifestation. These patterns differed from that of tolerant renal transplant patients, in whom marked and donor-specific reduction of CTL-p was observed. During rejection identical patterns with increasing donor-specific CTL-p frequencies were seen in both groups of patients. We conclude that induction of tolerance by short-term CsA to unmatched cornea grafts is not caused by clonal reduction of the effector precursor cell pool.     

Evaluation of long-term safety of the anti-IgE antibody, omalizumab, in children with allergic asthma.

OBJECTIVE: To evaluate the long-term effects of the anti-IgE antibody omalizumab in children with asthma. METHODS: This was a 28-week, double-blind, randomized, placebo-controlled trial with a 24-week open-label extension. In the core trial 225 children (ages 6 to 12 years) with moderate-to-severe allergic asthma requiring inhaled beclomethasone dipropionate (BDP) received omalizumab every 2 or 4 weeks, and 109 received placebo. BDP dosage was stable for weeks 1 to 16, then reduced during weeks 17 to 24 using strict safety criteria. The lowest dose for optimal asthma control was maintained for 4 more weeks. During the 24-week extension, all patients (n = 309) received open-label omalizumab in addition to other asthma medications. One-year safety data were analyzed. RESULTS: The incidence of adverse events in patients treated with omalizumab for 52 weeks was similar to those treated for 28 weeks in the core trial, which was generally comparable with placebo. In the 52-week omalizumab group, upper respiratory tract infection and headache were the most frequently reported adverse events (47.1% and 42.7%, respectively). Eleven patients (4.9%) reported urticaria, which resolved spontaneously or with antihistamine, except for 1 patient who was discontinued because of severe urticaria. No anaphylactic reactions or adverse events suggestive of serum sickness or immune complex formation occurred. No anti-omalizumab antibodies were detected in any of the children. There is no evidence that new or more serious adverse events occur with long-term omalizumab treatment. CONCLUSIONS: Long-term treatment with omalizumab is safe and well tolerated in children with allergic asthma.     

Einige Eigenschaften der Keimträgerstämme vonListeria monocytogenes

About 60 characteristics have been investigated in 7 hemolyzing and 12 non-hemolyzing strains ofL. monocytogenes. From these investigations resultedinter alia that the organism grows well under strictly anaerobic conditions, esculin is split at 45°C, NH₃ is produced from peptone, but not from arginin, and H₂S can be traced by sufficiently sensitive methods. All strains possess a lipase, muramidase, and deoxyribonuclease, the hemolytic ones only also a lecithinase. Besides, the hemolytic strains only dispose of experimental virulence and of a CAMP factor-like agent. The experimental animal of choice seems to be the conjunctivally infected guinea pig in which a generalized infection develops.     

Cytogenetic and comparative genomic hybridization findings in four cases of breast cancer after neoadjuvant chemotherapy

To assess a potential common pattern of genetic alterations in chemotherapy-resistant tumors we analyzed four tumors from breast cancer patients (patients 1-4) after neoadjuvant chemotherapy, by comparative genome hybridization (CGH) and conventional chromosome banding analysis. All patients showed structural aberrations involving chromosomes 1, 5, 11, 16, and 17. In CGH analysis, the patients showed typical imbalances for ductal breast cancer: gains of 1q (3 patients), 5q (2 patients), 8q (3 patients), and X (4 patients) and losses of 1p33 approximately p36 (3 patients), 16q (3 patients), 17p (3 patients), 19 (4 patients), and 22q (4 patients). Other recurrent imbalances of atypical pattern for ductal breast cancer were gain of 4q21 approximately q32 (2 patients), 20q21 approximately q22 (2 patients), and 21 (2 patients) and loss of 20p (3 patients). Three patients showed involvement of several regions bearing genes of drug resistance (MDR1 [HUGO symbol: ABCB1], BCRP [HUGO symbol: ABCG2], MRP1 [HUGO symbol: ABCC1], RFC1); the fourth patient displayed an amplification in the region of MYC (alias c-myc), thus providing--at the level of the light microscope--an explanatory background for the ability of their tumors to survive anthracycline-, taxane- and cyclophosphamide-based chemotherapy. Conventional cytogenetic analysis and CGH displayed highly coincidental findings in the tumors of four patients after neoadjuvant chemotherapy for breast cancer.