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Biomedical subjects

M A Lewis

Publications and source records attributed to M A Lewis.

At least 145 records · Page 8Linked to original sources

Phagocytosis of bacterial strains isolated from acute dentoalveolar abscess.

The phagocytosis by human polymorphonuclear leucocytes of 37 bacterial strains identified as Streptococcus milleri (10 strains), strictly anaerobic gram-positive cocci (10) Prevotella intermedia (6), Pr. oralis (5) and Fusobacterium nucleatum (6) was investigated in vitro. The ingestion of S. milleri and strictly anaerobic gram-positive cocci was significantly greater (p < 0.001) than that of strains of Prevotella spp. and F. nucleatum. The degree of uptake of capsulate and non-capsulate strains did not differ.

Acute Disease↗

Prediction of recovery in antenatally diagnosed hydronephrosis.

A series of 335 children with antenatally diagnosed hydronephrosis which persisted after the postnatal period was prospectively assessed. Idiopathic hydronephrosis (85 patients) and pelviureteric junction obstruction (73 patients) were the commonest conditions. All patients with idiopathic hydronephrosis were managed conservatively; 87% have had a complete resolution of hydronephrosis and 13% have remained unaltered. No patient managed conservatively has shown a deterioration in renal function.

Female↗

Pemphigus vulgaris precipitated by glibenclamide therapy.

Pemphigus vulgaris (PV) is a rare but potentially fatal autoimmune bullous disorder which frequently affects the oral mucosa. Although the essential cause of PV is unclear, its onset has occasionally been associated with drug therapy, in particular penicillamine. The patient described in this paper was a 78-year-old diabetic man who developed oral lesions of PV following institution of glibenclamide therapy.

Aged↗

Multiple admission and deprivation.

The relationship between multiple hospital admission (three or more) in early childhood and social deprivation was explored using data from two Sheffield whole year birth cohorts (1980 and 1985). The findings demonstrate a strong relationship between multiple admission for mainly, and exclusively, organic reasons and residence in an area of deprivation. The relationship persists when low birthweight infants and those with young mothers are excluded from the analysis. The results suggest a dual effect of deprivation on early childhood hospital admission; an increase in admissions associated with organic pathology and those associated with impaired parental coping.

Birth Weight↗

Immunofluorescent analysis of plasma fibronectin incorporation into the lung during acute inflammatory vascular injury.

Incorporation of plasma fibronectin into tissues is believed to influence endothelial cell-cell interaction, as well as endothelial cell adhesion to matrix. We used immunofluorescent microscopy coupled with tissue extraction of noncovalently incorporated fibronectin to delineate the time course for matrix incorporation of soluble plasma-derived fibronectin into the lung of sheep during postoperative bacteremia. Adult sheep were surgically prepared with both lung and peripheral lymph fistulas. Sheep were anesthetized 2 days following surgery and injected intravenously with a sublethal dose of live Pseudomonas aeruginosa, which consisted of 5 x 10(8) live organisms suspended in 0.9% saline. Bacterial infusion elicited a 300% increase in lung transvascular protein clearance but no increase in peripheral transvascular protein clearance. Purified dimeric human plasma fibronectin (hFn), used as an "immunologic marker," was then infused intravenously (100 mg/sheep) into two additional groups of sheep (nonbacteremic control group and bacteremic experimental group) and allowed to mix with the plasma pool of endogenous soluble sheep fibronectin (sFn). Incorporation of the plasma-derived hFn into the lung matrix and its distribution in relation to endogenous sheep fibronectin in the matrix was assessed by dual-label immunofluorescence using antibodies specific to either sFn or hFn. Human fibronectin from the vascular compartment codistributed with endogenous sheep fibronectin in the lung matrix. Moreover, its deposition into the lung was markedly increased in postoperative bacteremic sheep compared with nonbacteremic control sheep. Increased hFn deposition in the lung with bacteremia was clearly apparent within 2 h. The hFn deposited in the lung was nonextractable using a heparin-urea tissue extraction buffer, suggesting its rapid covalent cross-linking and incorporation into the lung matrix. Microscopic analysis of serial lung biopsies revealed focal areas of inflammation with an intense mononuclear infiltrate into the lungs by 2 h in the bacteremic sheep. Interstitial edema and vascular endothelial injury were observed by 4 h, with alveolar edema apparent over 6 to 8 h. Thus, postoperative bacteremia results in a rapid incorporation of plasma fibronectin into the lung matrix. This may be a physiologic mechanisms to stabilize the integrity of the lung vascular barrier.

Animals↗

Analysis of dynamic and stationary pattern formation in the cell cortex.

We study a sol-gel mechanochemical model for cellular cytoplasm. Using conservation equations and a force balance equation, we derive equations for the sol-gel dynamics. Regular perturbation analysis suggests the growth of patterns which may be either dynamic or stationary, depending on parameter values. Nonlinear analysis, which indicates that these patterns remain bounded, is confirmed by numerically solving the mechanochemical equations. We use these analytical and numerical results to model two different biological problems: the dynamic formation of filopodia in nerve growth cones, and the growth of microvilli in epithelial cells.

Actins↗

Practical peritoneal dialysis--the Tenckhoff catheter in acute renal failure.

The problem of acquiring secure peritoneal access encompasses most of the history of peritoneal dialysis. We review the catheters available for children and describe a simple method of insertion of Tenckhoff catheters for acute dialysis. Two series of Tenckhoff catheters inserted in this way are presented and compared with results obtained with trocar- and guidewire-inserted catheters. Tenckhoff catheters inserted as described allow significantly longer periods of dialysis (P < 0.02) with significantly fewer problem episodes (P < 0.001). We conclude that the use of the Tenckhoff catheter for acute dialysis, when inserted in the way described, confers significant advantages over other catheters and permits secure peritoneal access.

Acute Kidney Injury↗

Determination of the rate-limiting step(s) in the biosynthetic pathways leading to penicillin and cephalosporin.

This paper is a review of strategies that have been used, or that could be used, to determine the rate-limiting step(s) in the biosynthetic pathways leading to penicillin or cephalosporin. Information is summarized from published material that involves studies with low-producing strains of Penicillium chrysogenum and Cephalosporium acremonium. We also summarize information derived from some high-producing production strains. Identification of the rate-limiting step(s) was of great interest to us as the first step in a rational program to further improve antibiotic titers of these highly developed strains. A number of approaches that could be used to elucidate the rate-limiting step(s) are described herein.

Acremonium↗

Accuracy in perceptions of interpersonal interactions: effects of dysphoria, friendship, and similarity.

Conflicting views of depressives' interpersonal accuracy were addressed in an investigation of the accuracy of mild depressives (dysphorics) across differing social contexts. Women who were either friends or strangers and who were either similar or dissimilar in level of dysphoria conversed about 3 topics: a neutral topic, their own disclosure of a personal problem, and their partner's disclosure. Dysphorics were not more accurate in general than nondysphorics. After self-disclosure, all women more accurately detected sympathy from a similar stranger. After the partner's disclosure, women also better detected the mood of a similar partner. When interacting with nondysphoric strangers, however, dysphorics underestimated their partner's sympathy toward them. Implications for cognitive and interpersonal theories of depression and for depressives' relationships are discussed.

Depression↗

Oral presentation of the Laugier-Hunziker syndrome.

Laugier-Hunziker syndrome is an extremely rare disorder but is of some interest to dental practitioners. The importance of the condition relates to it being included in the differential diagnosis of pigmentary disorders of the oral mucosa with associated nail involvement. Two cases of the syndrome are described.

Adult↗

One-way blocks in cardiac tissue: a mechanism for propagation failure in Purkinje fibres.

The concept of a one-way block, arising from a region of depressed tissue, has remained central to theories for cardiac arrhythmias. We show that both the geometry of a depressed region and spatial heterogeneities in depression are key factors for inducing such a block. By using an asymptotic approximation, known as the eikonal equation, to model qualitatively the movement of a depolarization wave-front down a Purkinje fibre bundle, we show how a one-way block in conduction may result from asymmetric constriction in the width of a depressed bundle. We demonstrate that this theory is valid for biologically relevant parameters and simulate a one-way block by numerically solving the eikonal approximation. We consider the case of non-uniform depression, where the planar travelling wave speed is spatially dependent. Here, numerical simulations indicate that such a spatial dependency may, in itself, be sufficient to produce a one-way block.

Animals↗

Policy and implementation of user fees in Jamaican public hospitals.

User fees and other forms of copayment for health care are becoming of increasing interest to policymakers in developing countries. As indigenous populations continue to expand in response to current and historically high fertility, and government resources become constrained due to macroeconomic circumstances, publicly provided health care is being squeezed financially. Most developing countries have committed their governments to either providing for all health care or at least ensuring that all citizens have access to health care regardless of ability to pay. This has translated in most contexts into blanket coverage for the entire population financed and generally provided by the government. Recent periods of slow growth, high debt burdens and restricted spending on high recurrent cost sectors, such as health care under International Monetary Fund and other donor agreements have reduced many developing countries' budgets and often the real value of health expenditures. The costs of inputs (personnel, drugs and consumables), however, have not declined and quality or quantity have been necessarily reduced. At the same time, options for financial relief outside the tax system have become of increasing interest to financially constrained governments. User charges are straightforward, easily understood and can in theory be profitable in the short term. From a fairness perspective, they also charge those who actually use the health system. Their major drawback for policymakers is the potential for undermining equity in the health system.

Budgets↗

Diagnosis and treatment of oral candidosis.

Oral candidosis is a common opportunistic infection that manifests in a variety of forms. It is also recognized as one of the earliest manifestations of human immunodeficiency virus (HIV) infection. Although a number of antifungal agents are available for the treatment of this condition, a newly introduced triazole group of drugs appears to be highly effective in treating oral candidosis. This article reviews the clinical presentation and management of oral candidosis, particularly with reference to the latter group of drugs and HIV-induced disease.

Antifungal Agents↗

Systemic fluconazole therapy and in vitro adhesion of Candida albicans to human buccal epithelial cells.

The adhesion of Candida albicans to buccal epithelial cells (BEC) from four healthy dentate men was studied in vitro 1 wk before, during and after a course of systemic fluconazole (50 mg once daily for 1 wk). After 1 wk of fluconazole intake candidal adhesion to BEC was significantly reduced and this reduction persisted for a week following completion of therapy. Fluconazole, therefore, in addition to being an effective antifungal agent may also have a sustained action on reducing adherence of candidal species to the oral mucosa.

Adult↗

Multiple admissions under 2 years of age.

Hospital admission rates before 2 years of age are reported for two complete birth cohorts born within a geographically defined area five years apart in 1980 and 1985. Admission rates for individual children in the cohort before 2 years of age showed an increase between 1980 and 1985 from 209 to 247 children/1000. The most significant increase took place in those children admitted three or more times (multiple admissions). Children admitted once only increased significantly but there was no significant change in the number of children admitted twice. A total of 2.3% of the total cohort in 1980 and 3.6% in 1985 were admitted three or more times and accounted for over 30% of all admissions. Age specific rates are reported for the 1985 cohort; 36% of those admitted had their first admission before 3 months of age and 76% before their first birthday. The disproportionate contribution of children with multiple admissions to the admissions total renders admission data from Hospital Activities Analysis invalid unless linked to individual children. Cohort data based on a geographically defined population provide the most reliable admission rates and permit an accurate analysis of trends. The significance of and reasons for the upward trend in early childhood admissions are discussed.

Age Factors↗