Flash photolysis of the carbon monoxide compounds of wild-type and mutant variants of cytochrome bo from Escherichia coli

The carbon monoxide compounds of the fully reduced and mixed valence forms of cytochrome bo from Escherichia coli were laser photolysed under anaerobic conditions at room temperature. The carbon monoxide recombined with characteristic rate constants of 50 s-1 or 35 s-1 in the fully reduced and mixed valence forms, respectively. Rates of CO recombination with the fully reduced enzyme were examined in a variety of mutant forms of cytochrome bo, produced by site-directed mutagenesis. A method was developed to deconvolute cytochromes bo and bd, leading to some reassessment of histidine ligands to the metals. Significant changes in the rate constant of recombination of carbon monoxide occurred in many of these mutants and these results could be rationalised generally in terms of our current working model of the folding structure of subunit I. In the mixed valence form of the enzyme the transient photolysis spectra in the visible region are consistent with a rapid electron redistribution from the binuclear centre to the low-spin haem. This electron transfer is biphasic, with rate constants of around 10(5) and 8000 s-1. The process was also examined in the His-333-Leu mutant, in which a putative histidine ligand to CuB is replaced by leucine, and which results in the loss of the CuB. It appeared that rapid haem-haem electron transfer could still occur. The observation that CuB is apparently not required for rapid haem-haem electron transfer is consistent with the recently proposed model in which the two haems are positioned on opposite sides of transmembrane helix X in subunit I of the oxidase.     

Meat tenderness and the calpain proteolytic system in longissimus muscle of young bulls and steers

The objectives of this study were to examine the effects of castration on the calpain proteinase system (mu-calpain, m-calpain, and calpastatin) activities and meat tenderness. Six each, MARC III bulls and steers were slaughtered at approximately 12 mo of age. Longissimus muscle samples were obtained for determining myofibril fragmentation index, Warner-Bratzler shear force, and sensory panel evaluation at 1, 7, and 14 d postmortem, and mu- and m-calpain and calpastatin activities at 24 h postmortem. Bulls produced leaner carcasses with lower (P < .05) quality grades than did steers. Meat from bulls had higher (P < .05) shear force values than meat from steers; however, sensory panelists were unable (P > .05) to detect differences in tenderness or other sensory traits between bulls and steers. Activities of mu- and m-calpain were not affected (P > .05) by castration; however, calpastatin was higher (P < .05) in muscles from the bull carcasses. Lower (P < .05) myofibril fragmentation index values indicate that less proteolysis occurred in muscle from bulls than in muscle from steers during the first 7 d postmortem. Greater calpastatin 24-h activity may be associated with the increased shear force of meat from bulls.     

European medical schools and tobacco

Following a survey in 19 European countries of the habits, attitudes and knowledge of medical students regarding tobacco, World Health Organisation European Office and the International Union against Tuberculosis and Lung Disease jointly circulated to the Deans of all European medical schools a summary of the results, including figures for mortality for smoking-related diseases in their countries and a brief questionnaire concerning faculty action on the tobacco problem. The response rate was just over 50%, higher in Northern Europe (66%) than in Southern (35%) or Eastern (38%). Only 8% of faculties had a specific teaching module on tobacco. In most it was either systematically (35%) or unsystematically (55%) integrated in other teaching. Teaching hospitals, teaching areas and faculty meetings were said to be smokefree by over 90%; figures were lower for other areas. Seventy-seven per cent of Deans intended to discuss our approach with their teaching staff; 72% gave the name of a staff member with a particular tobacco interest.     

Invasive group A streptococcal disease in Taiwan is not associated with the presence of streptococcal pyrogenic exotoxin genes

We reviewed the clinical features of 44 patients with invasive group A streptococcal (GAS) disease who were treated at two teaching hospitals in southern Taiwan from 1991 to 1994. Genes encoding streptococcal pyrogenic exotoxin types A (speA), B (speB), C (speC), and F (speF) and serotypes of M1, M6, and M12 were determined by polymerase chain reaction to target specific sequences in the 44 isolates recovered from these patients and in 28 isolates recovered from upper respiratory sites in 28 additional patients during the study period. The protease activity of these isolates was tested by using the casein plate method. Of the 44 patients with invasive diseases, 25 (57%) had no obvious underlying diseases, and 14 (32%) had preexisting neoplastic diseases or had previously used steroids. Twenty-five patients (57%) presented with cellulitis or necrotizing fasciitis, 24 (55%) had bacteremia, and eight (18%) had streptococcal toxic shock syndrome (STSS). Eight patients (18%) died of invasive GAS disease; seven had STSS, and seven had underlying diseases. All eight patients died within 48 hours after hospitalization. The presence of speA, speC, or speF was not implicated in any particular clinical syndrome in patients with invasive GAS disease. High-level protease activity and the M1 serotype of the isolates were significantly associated with the clinical signs of STSS and with mortality. M1 serotype and protease activity, as well as host immune status, might play significant roles in the pathogenesis of invasive GAS disease in Taiwan.     

In vivo surface analysis of titanium and stainless steel miniplates and screws

OBJECTIVE: To determine the results peranal excision for rectal carcinoma. DESIGN: Retrospective case series. SETTING: A university-affiliated hospital. PATIENTS: Of 178 patients who presented for curative resection of rectal carcinoma between 1975 and 1993, 19 (10.7%) were deemed suitable for local excision. There were 10 men and 9 women with a mean age of 71.2 years. The follow-up ranged from 13 to 184 months. INTERVENTION: Peranal excision. MAIN OUTCOME MEASURES: Histologic differentiation, gross morphology, depth of invasion and size of the carcinoma, adequacy of margins of excision, complications of operation, rates of recurrence, results of salvage therapy and 5-year survival. RESULTS: There were no intraoperative complications. Postoperative complications included urinary retention (one patient) and bleeding (one patient). There were five local recurrences (26%). Salvage operations were performed in three (60%) patients and were successful in two of them. The 5-year cancer-specific survival rate was 82%. The recurrence rate was higher in patients with inadequate margins of excision and ulcerative lesions. Neither size nor grade of the carcinoma correlated with recurrence. CONCLUSIONS: Local excision of rectal carcinoma can be performed successfully in selected patients. Diligent follow-up is required, because up to 60% of local recurrences can be treated successfully.     

Cystic fibrosis. Gastrointestinal complications and gene therapy

The gastrointestinal and nutritional complications of cystic fibrosis are diverse. As longevity improves in patients with cystic fibrosis, management of these complications is becoming increasingly important . This article provides overviews of the molecular aspects of the pathogenesis of cystic fibrosis, the current status of gene therapy, and a review of the gastrointestinal manifestations and nutritional care.     

Machine milking of dairy goats during lactation: udder anatomy, milking characteristics, and blood concentrations of oxytocin and prolactin

Forty-four goats were milked and milk flow recorded without or with 1 min manual prestimulation in early, mid and late lactation. Ultrasound measurements of cross sections of the whole mammary gland were performed in a water bath. In additional experiments with 15 goats, milk flow was recorded and frequent blood samples were taken for the determination of oxytocin and prolactin concentrations. Milk yield increased from the first to the third lactation and decreased markedly during the course of lactation. Average and peak milk flow rates were closely related to the actual milk yield. The ultrasound cisternal area was 27.4 +/- 1.5% of the entire udder half cross section. Milking characteristics were scarcely different without or with prestimulation, although oxytocin was released within 30 s after the start of prestimulation, whereas oxytocin concentrations without prestimulation increased only after the start of milking. Concentrations of prolactin were higher during July and August than in April, and increased similarly with or without prestimulation during milking. In contrast to dairy cows, prestimulation and an opportune release of oxytocin during milking does not significantly influence the course of milk flow in goats, and this is probably because large amounts of cisternal milk allow milk ejection to be induced only after the start of milking without causing bimodal or otherwise reduced milk flow.     

Acute cadmium exposure and ovarian steroidogenesis in cycling and pregnant rats

The purpose of this study was to evaluate the effect(s) of acute in vivo cadmium (Cd) exposure on steroidogenesis in rat ovaries during different reproductive states. Sprague-Dawley rats were injected subcutaneously on the day of diestrus, or on day 7 or 16 of gestation with a single dose of 0, 3, or 5 mg Cd/kg bw, and evaluated 24 h later. Serum progesterone and estradiol concentrations were determined. Whole-ovary culture was used to evaluate Cd effects on the production of progesterone, testosterone, and estradiol. Liver, kidney, spleen, ovary, placenta, and blood were analyzed for Cd and iron (Fe) concentrations. No general toxic effects, no disruption of estrous cyclicity, and no change in fetal viability were seen. Histologic evaluation revealed moderate Cd-related thecal congestion in ovaries of pregnant rats. The highest Cd concentrations, except for liver, were found in the fetal portion of the placenta. Interestingly, Cd-related decreases in Fe concentration were found in several tissues from rats in proestrus and on gestation day 8, and in fetal placenta from rats on gestation day 17. Cadmium appears to interfere with normal steroidogenesis at a number of sites in the biosynthetic pathway with serum estradiol concentration and ovarian estradiol production the most affected. Acute Cd effects on steroidogenesis are most severe in rats evaluated in proestrus or in early pregnancy, while in late pregnancy steroidogenesis is relatively unaffected.     

Survival of patients with carcinoma of the esophagus treated with combined-modality therapy

Since 1985, 229 cases of carcinoma of the esophagus have been considered for entry into a protocol with the use of preoperative chemotherapy and radiation therapy followed by surgical intervention as the primary element of treatment. One hundred sixty-five patients (93 with adenocarcinoma and 72 with squamous cell carcinoma) had esophagogastrectomy. The 5-year survival of the protocol patients who underwent resection was 25% for both groups--squamous cell carcinoma and adenocarcinoma. Of the protocol patients with squamous cell carcinoma who underwent resection, 40% had a sterilized specimen, whereas of those with adenocarcinoma, 20% had a sterilized specimen. If the patient had a sterilized specimen, the 5-year survival was approximately 60% for adenocarcinoma and 40% for squamous cell carcinoma. Those patients with adenocarcinoma and Barrett's esophagus had a 5-year survival of 55%. Of the patients who underwent only esophagectomy and esophagogastrectomy and had not been entered into the protocol, none lived beyond 3 years. The operative mortality rate for those who had esophagogastrectomy was 5%. Sixty-four patients completed the radiation therapy and chemotherapy but did not undergo surgical procedures because of progressive disease or refusal. Of those patients who completed chemotherapy and radiation therapy without surgical intervention, 5-year survival was 18% in patients with squamous cell carcinoma, whereas no patients with adenocarcinoma survived beyond 3 years. The finding of a sterilized specimen after esophagectomy is a favorable prognostic factor in patients with adenocarcinoma or squamous cell carcinoma. The finding that patients with Barrett's esophagus and adenocarcinoma have an improved chance for survival is perhaps related to an earlier diagnosis. It is clear that some patients with squamous cell carcinoma who did not undergo surgical procedures did have a sterilized specimen, because the survival in this group approached 20% at 5 years.