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Biomedical subjects

M Stephens

Publications and source records attributed to M Stephens.

At least 91 records · Page 5Linked to original sources
PubMed1987

Synchronous duodenal neuroendocrine tumours in von Recklinghausen's disease--a case report of co-existing gangliocytic paraganglioma and somatostatin-rich glandular carcinoid.

The co-existence of a gangliocytic paraganglioma and a glandular psammomatous carcinoid in the duodenum of a patient with von Recklinghausen's disease and bilateral phaeochromocytomas is reported. The two lesions were considered to be distinctive by light microscopy, electron microscopy and immunocytochemistry. The cells of the glandular carcinoid showed strong cytoplasmic immunoreactivity for somatostatin and contained only scanty intracytoplasmic microfilaments on electron microscopy. In contrast, the endocrine cells of the gangliocytic paraganglioma were positive for pancreatic polypeptide and serotonin, were negative for somatostatin, and contained conspicuous intracytoplasmic aggregates of filaments. The histogenic relationship between the two tumours is discussed. This case strengthens the known association of glandular duodenal somatostatinoma with von Recklinghausen's disease and phaeochromocytoma and, in the light of a previous case report, suggests that von Recklinghausen's disease and gangliocytic paraganglioma may co-exist more commonly than expected.

Carcinoid Tumor↗
PubMed1987

Asbestos induced diffuse pleural fibrosis: pathology and mineralogy.

Lungs from seven cases of diffuse pleural fibrosis with known asbestos exposure were studied to determine the gross and microscopic pathological features and relate these to the analysed mineral fibre content of the lung. All seven individuals had had substantial exposure, ranging from two to 25 years, and chronic chest problems and at necropsy all cases met the criteria for compensatable disease. Macroscopically, all had extensive visceral pleural fibrosis and extensive areas of adhesions, and four also had discrete parietal pleural plaques. The histological features were similar in all the cases--most strikingly the basket weave pattern of the thickened pleura and a dense subpleural parenchymal interstitial fibrosis with fine honeycombing, extending up to 1 cm into the underlying lung. The similar histological appearances raise the possibility that diffuse pleural fibrosis and pleural plaques have a similar pathogenesis. Amphibole asbestos (crocidolite and amosite) counts were high in six of the seven cases and chrysotile counts in four; four cases had high mullite counts, but the importance of this is not known. It is concluded that diffuse pleural fibrosis is a specific asbestos associated entity, of uncertain pathogenesis, with mineral fibre counts falling between those found with plaques and those in minimal asbestosis.

Asbestos↗
PubMed1987

Pharmacokinetics of ciprofloxacin in the elderly.

The pharmacokinetics of ciprofloxacin, administered orally as a 250-mg tablet were compared in 10 young (age 20-30 years) and 10 elderly (age 60-73 years) healthy volunteers. The time to peak serum concentrations was about 80 min in both age groups, although the maximum concentration attained was significantly greater in the old (1.7 mg/l) than the young (1.2 mg/l). Area under the plasma concentration-time curve, corrected for body weight, was on average 48% greater in the elderly, but the mean terminal elimination half-life was not significantly different, averaging 4.3 h in the old and 3.7 h in the young. Overall 24-hour urinary recovery in both age groups was comparable. The differences may be explained by a reduced volume of distribution of ciprofloxacin in old age and do not suggest a general need for significant dose alteration in the elderly.

Administration, Oral↗
PubMed1985

Methicillin-resistant Staphylococcus aureus (MRSA): risk and outcome of colonized vs. infected patients.

A retrospective study of 204 patients culture positive for methicillin-resistant Staphylococcus aureus compared infected and colonized patients. Seventy-eight patients were colonized and never developed infection (C), 24 were colonized and subsequently infected (C----I), and 102 patients had 1 or more nosocomial infections with MRSA at time of first culture (I). The most prevalent sites of infection were wound (26.5%) and blood-stream (20.7%), whereas the respiratory tract and surgical wounds were both frequent sites of colonization. Stepwise discriminant analysis found the most important factors in differentiating likelihood of colonization vs. infection were recent prior hospitalization, history of wound debridement, and number of invasive procedures. Ten percent of (C) died and 25.5% of (I) died. MRSA contributed to death in 57.6% of the (I) deaths (p less than .05). These results underscore the importance of differentiating (C) vs. (I) in hospitals where MRSA is endemic so that early specific treatment may be initiated. Risk factors for infection should be discriminated from those for acquisition of the organism.

Cross Infection↗
PubMed1982

Nucleotide sequences that signal the initiation of transcription and translation in Bacillus subtilis.

We have determined the nucleotide sequence of two Bacillus subtilis promoters (veg and tms) that are utilized by the principal form of B. subtilis RNA polymerase found in vegetative cells (sigma 55-RNA polymerase) and have compared our sequences to those of several previously reported Bacillus promoters. Hexanucleotide sequences centered approximately 35 (the "--35" region) and 10 (the "--10" region) base pairs upstream from the veg and tms transcription starting points (and separated by 17 base pairs) corresponded closely to the consensus hexanucleotides (TTGACA and TATAAT) attributed to Escherichia coli promoters. Conformity to the preferred --35 and --10 sequences may not be sufficient to promote efficient utilization by B. subtilis RNA polymerase, however, since three promoters (veg, tms and E. coli tac) that conform to these sequences and that are utilized efficiently by E. coli RNA polymerase were used with highly varied efficiencies by B. subtilis RNA polymerase. We have also analyzed mRNA sequences in DNA located downstream from eight B. subtilis chromosomal and phage promoters for nucleotide sequences that might signal the initiation of translation. In accordance with the rules of McLaughlin, Murray and Rabinowitz (1981), we observe mRNA nucleotide sequences with extensive complementarity to the 3' terminal region of B. subtilis 16S rRNA, followed by an initiation codon and an open reading frame.

Bacillus subtilis↗
PubMed1982

Prospective survey of fecal, urinary tract, and environmental colonization by Providencia stuartii in two geriatric wards.

A prospective survey of fecal, urinary tract, and environmental colonization by Providencia stuartii in two wards was undertaken over a 5-month period. Eight of 53 male patients and 2 of 89 female patients were colonized with the endemic serotype O:63. Two patterns of colonization were found on the male ward. Two patients had persistent urinary tract colonization with no detectable fecal carriage. The other patients had fecal carriage, in some cases persistent, with intermittent urinary tract colonization. The ward environment was in general not contaminated. This study demonstrates that fecal colonization of patients by P. stuartii may be an important and previously underestimated nosocomial reservoir.

Aged↗
PubMed1982

Environmental antecedents which affect management and maintenance of programs for self-injurious behavior.

This paper reports the effects of several environmental variables on the management and maintenance of a treatment program for self-injurious behavior (SIB) in residents in a state facility for retarded persons. Fifteen of the clients who participated in a developmental day-care program were compared across the final four months of the program and then at follow-up two years later. Twelve additional clients who were treated in the overall SIB program did not receive the day-care component, but were included in the follow-up study. Regarding program management, the effects of time, staff-initiated interactions, the presence of a newcomer or disruptive client, and medication changes on the behaviors of the 15 clients in the day-care program were assessed from an ecobehavioral approach. Participants in the follow-up study were compared with respect to the type of SIB program they received, the staff-patient ratio in their program, their visual impairment, use of self-protective devices, presence of stimulating material, and time-of-day observed. These issues are discussed in relation to program maintenance.

Adolescent↗
PubMed1979

The sensitivity of gentamicin-resistant gram-negative bacilli to cefotaxime, other cephalosporins and aminoglycosides.

The sensitivities of 80 gentamicin-resistant gram-negative bacilli to cefotaxime, cefuroxime, cefoxitin, cefamandole, cefazolin, tobramycin, netilmicin and amikacin were determined. Amikacin was the most active amino-glycoside. However, the percentage sensitivity to cefotaxime of most of the species was higher than, or equal to any of the other antibiotics tested. Cefotaxime was particulary active against Providencia spp., Serratia spp., Klebsiella spp., and Pseudomonas maltophilia, being 16 to 256 times more active than the next best cephalosporin or cephamycin. Clinical trials of cefotaxime are now required.

Acinetobacter↗
PubMed1978

A hospital epidemic caused by gentamicin-resistant Klebsiella aerogenes.

In the 15 months, February 1976 to April 1977, more than 241 patients became colonized with a strain of Klebsiella aerogenes, capsular serotype K2, resistant to most antibiotics. Urinary tract infection was the most common clinical manifestation but bacteraemia and, occasionally, infections of other sites were encountered. The main reservoir of the epidemic klebsiella was the gut, urine and skin of colonized patients. Gut carriage among staff was very uncommon. The most susceptible patients were elderly males, with debilitating illnesses and urinary tract abnormalities, especially if they were catheterized or receiving antibiotics. Likely vehicles for spread were the hands of staff, and contaminated bedpans and urinals. Control measures were directed at these factors. At the end of April 1977 no new cases had occurred for 3 months in the ward in which the outbreak began, and which had been the main focus of infection, and only 5 patients in the affected hospitals were known to be colonized by the epidemic klebsiella.

Cross Infection↗
PubMed1978

Urinary tract infection in young women, with special reference to Staphylococcus saprophyticus.

Acute urinary tract infections in young women attending a clinic for sexually transmitted diseases were caused by the same bacteria, in the same proportions, as those that caused infections in women students. Staphylococcus saprophyticus biotype 3 (formerly called Micrococcus subgroup 3) was the commonest organism after coliform bacilli and caused about 30% of the infections. It was uncommon in women over 25 years of age and rarely caused asymptomatic bacteriuria in pregnancy. Most infections, irrespective of the causative organism, started soon after sexual intercourse, but neither the staphylococci nor the other organisms were associated with promiscuity, as judged by numbers of sexual partners or the incidence of sexually transmitted diseases. There was no evidence that the staphylococci were sexually transmitted. The reasons for the virulence of Staph. saprophyticus and its predilection for the urinary tract of young women remain unknown.

Adult↗