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Biomedical subjects

M Lewis

Publications and source records attributed to M Lewis.

At least 199 records · Page 11Linked to original sources
PubMed1995

Bovine osteodystrophies.

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Animal Nutritional Physiological Phenomena↗
PubMed1995

Stability and change in cortisol and behavioral response to stress during the first 18 months of life.

Observation of cortisol and behavioral responses to routine inoculation was conducted at 18 months for infants in a longitudinal sample whose stress responses had been observed at 2, 4, and 6 months of age. At 18 months, infants showed an increase in cortisol level over base to the perturbation. The magnitude of this response did not differ from the 6-month response. Moreover, level of cortisol response at 18 months was related to level of cortisol response at 6 months, but not at 2 or 4 months of age. In light of previous findings for a decline in cortisol response between 2 and 6 months had for the emergence of consistent individual differences in cortisol response by 4 to 6 months, the present findings indicate that a developmental shift in adrenocortical functioning has occurred by 6 months of age.

Adaptation, Psychological↗
PubMed1995

Characteristics of Staphylococcus aureus strains isolated from clinical and non-clinical human sources in Trinidad: susceptibility to bacteriophages and antimicrobial agents, and toxigenicity.

The susceptibility of Staphylococcus aureus strains isolated from human clinical and non-clinical sources in Trinidad to bacteriophages and antimicrobial agents was determined. The ability of the strains to produce enterotoxins and toxic shock syndrome toxin-1 (TSST-1) was also investigated. Of the 554 strains tested, 454 (81.8%) were susceptible to international phage set (IPS) phages with strains isolated from bacteruria (57.1%) and bacteremia (53.3%) having a low sensitivity compared to isolates from aspirates (87.3%) and anterior nares (97.4%). All sources combined, strains were most susceptible to phages belonging to several groups (mixed). Overall, 419 (75.6%) strains were resistant to one or more of nine antimicrobial agents tested. Resistance to penicillin was most prevalent, with 413 (74.5%) strains found to be resistant. Prevalence of resistance to tetracycline, gentamicin, oxacillin, cefuroxime and ciprofloxacin was 5.1%, 2.0%, 0.7%, 0.4% and 0.4%, respectively. Of the 554 strains tested, 307 (55.4%) produced staphylococcal enterotoxins A (SEA), B (SEB), C (SEC) and D (SED) singly or in combination. Strains recovered from high vaginal swabs were least enterotoxigenic (40.0%) as compared to umbilical infection isolates which were most enterotoxigenic (78.9%). TSST-1 was produced by 95 (19.0%) out of 499 strains tested, with isolates from bacteruria found to be most toxigenic (33.3%). It was concluded that the S. aureus strains tested were highly susceptible to bacteriophages and antimicrobial agents (except penicillin) and that enterotoxigenic and TSST-1 producers were widespread and have an aetiologic potential.

Anti-Bacterial Agents↗
PubMed1995

Retinoblastoma with micrometastasis to CSF.

A 28 mth old male presented with a squint and leukocoria. Clinical examination and computerized tomography (CT) suggested a unilateral retinoblastoma with distal optic nerve involvement. Investigations for distant metastasis including lumbar puncture cytology were negative. The eye was enucleated and 12 mm of optic nerve was excised via a combined neurosurgical/ophthalmological approach. Histopathological examination confirmed the optic nerve to the point of excision was free of tumor. However, cytology of cerebrospinal fluid (CSF) from the Sylvian fissure, taken at the time of surgery, revealed malignant retinoblastoma cells. The patient was treated with intrathecal and intravenous chemotherapy, and cranial radiotherapy. He is alive and well 4 yrs later. This case displays the importance of CSF cytology from the Sylvian fissure, as it dramatically changed the management and prognosis for the child. The role of lumbar puncture cytology in excluding CSF micrometastasis can be unreliable. A neurosurgical approach to the optic nerve has the potential to gain access to a long length of optic nerve, should it be involved with tumor, and also allows direct CSF sampling.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

A double-blinded prospective evaluation of recombinant human erythropoietin in acutely burned patients.

OBJECTIVE: To evaluate the effects of recombinant human erythropoietin (r-HuEPO) in attempting to prevent anemia in acutely burned patients. DESIGN: Prospective double-blind randomized study of 40 patients. METHODS: Patients with burns from 25% to 65% total body surface were enrolled. r-HuEPO or a placebo was begun within 72 hours of admission. Cell blood count, reticulocyte counts, transfusion requirements, and blood loss were measured. Comparison was carried out by the unpaired t test. MAIN RESULTS: There was no statistically significant difference in hemoglobin, hematocrit, reticulocyte count, ferritin, serum iron, total iron blinding capacity, or transfusion requirements. In patients with burns from 25% to 35%, the reticulocyte counts were statistically significantly higher. CONCLUSION: In our work the administration of r-HuEPO in acutely burned patients did not prevent the development of postburn anemia or decrease transfusion requirements. Increased erythropoiesis in smaller burns (25% to 35%) was observed and may indicate a reason for further study.

Adolescent↗
PubMed1995

Hypothalamic mediation of reduced GH secretion in diabetic rats: evidence for reduced cholinergic inhibition of somatostatin release.

The Goto-Kakizaki (GK) rat is a new model of diabetes mellitus and in this study we have characterized the diabetic and growth hormone (GH) secretory status of male GK rats at 6 and 16 weeks of age. We have also investigated the role of endogenous somatostatin (SS) and cholinergic manipulation on the GH responses to GH-releasing hormone (GHRH). GK rats were non-obese with significant fasting hyperglycaemia, hyperinsulinaemia and absent insulin responses to IV glucose. The GH response to GHRH was reduced at 16 weeks compared with normal, age-matched Wistar rats but no differences were observed at 6 weeks. Pretreatment of older rats (16 weeks) with anti-somatostatin antibodies (SS-Ab) significantly increased GH responses to GHRH in both normal and GK groups. Cholinergic augmentation with pyridostigmine (PD) reversed the blunted GH responses to GHRH in older GK rats but had no effect in the normal or young (6 weeks) GK rats. These results indicate that SS release mediates the blunted GH response to GHRH in GK rats and that reduced hypothalamic cholinergic signalling to the somatostatinergic neurone may mediate the increase in SS release. This view is supported by the results from in vitro studies in which cholinergic muscarinic blockade with pirenzepine (PIR) caused dose-related stimulation of SS release from normal rat hypothalami but was without effect on GK rat hypothalami. The cause of this alteration in hypothalamic function is, at present, unknown.

Acetylcholine↗
PubMed1995

Developmental change in infants' responses to stress.

Infant stress responses to a well-baby physical examination and inoculation were observed longitudinally at 2, 4, and 6 months of age. In general, there were cortisol increases over base to the procedures. Cortisol level and cortisol response decreased with age. These data indicate a developmental shift in adrenocortical functioning between 2 and 6 months of age. Further evidence for this shift was seen in the stability of individual responses between 4 and 6 months of age. Individual differences in both cortisol and behavioral responses showed the most stability between these 2 ages. Moreover, diurnal variation in baseline cortisol level was present only at 6 months of age. While a sizable minority of infants showed stress-related cortisol decreases to the procedures at a given age, there was no evidence for cross-age consistency in individual infants showing these cortisol decreases.

Age Factors↗
PubMed1995

Novel hypotheses for the roles of EBNA-1 and BHRF1 in EBV-related cancers.

Epstein-Barr virus has been linked to several types of human cancer including Burkitt's lymphoma and nasopharyngeal carcinoma but the mechanisms by which the virus might contribute to cancer remain obscure. Here we consider the possibility that EBNA-1, which is expressed in both tumours, directly transactivates cell genes. The EBNA-1 protein was tested for transcription transactivation domains and the human genome was screened for high-affinity EBNA-1-binding sites that might mediate transactivation. None were found, although novel low-affinity-binding sites in the EBV genome were detected. We also investigated the expression of BHRF1, the viral homologue to bcl-2, in epithelial cells and showed that it is expressed in vivo in the EBV replication found in oral hairy leukoplakia. A novel hypothesis is proposed for nasopharyngeal carcinoma in which BHRF1 expression protects cells against apoptotic death caused by environmental DNA damaging agents and thus contributes to the early stages of cancer development.

Antigens, Viral↗