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Biomedical subjects

M A Lewis

Publications and source records attributed to M A Lewis.

At least 163 records · Page 9Linked to original sources
PubMed1991

Kinetics of plasma fibronectin: increased lung tissue incorporation after postoperative bacteremia.

Fibronectin is an adhesive glycoprotein that may influence the permeability of the vascular barrier. We compared the plasma disappearance of purified human fibronectin (hFn) and its incorporation into lung tissue in control nonbacteremic and bacteremic sheep after surgery to determine the influence of postoperative bacteremia on the plasma clearance and lung deposition of hFn. Lymph fistulas were surgically prepared 48 h before either saline or bacterial challenge to allow for collection of timed samples of plasma, lung lymph, and peripheral lymph. On the day of the study, the sheep were anesthetized and given either 5 X 10(8) Pseudomonas aeruginosa in saline or saline alone. In parallel, they were infused intravenously with 100 mg of hFn, and the hFn concentration in plasma, lymph, and tissue extracts was subsequently determined by enzyme-linked immunosorbent assay over an 8-h experimental interval. Localization of endogenous sheep fibronectin (sFn) and the injected hFn in serial lung tissue samples was determined by dual-label immunofluorescence. In nonbacteremic control sheep, plasma hFn levels declined with an initial rapid slope (t1/2 = 0.53 +/- 0.19 min), followed by a second, gradual slope (t1/2 = 21.7 +/- 2.5 h), whereas the concentration of hFn in lung lymph and peripheral lymph rose exponentially with time. In bacteremic sheep, the early plasma disappearance of hFn was similar, but the second phase of plasma clearance was faster (t1/2 = 7.4 +/- 0.3 h). Lung tissue from control and bacteremic sheep contained the same level of extractable hFn. However, tissue extraction followed by immunofluorescence microscopy indicated that lung tissue from bacteremic sheep contained more nonextractable hFn than lung tissue from nonbacteremic sheep. Thus postoperative bacteremia that elicits acute lung vascular injury will increase the plasma disappearance of hFn and its incorporation into the lung tissue.

Animals↗
PubMed1991

Clinical application of computerized continuous-infusion pressure-monitored sialography.

The clinical application of computerized continuous-infusion pressure-monitored sialography using an aqueous contrast medium during the investigation of 296 salivary glands is described. A comparison between the pressure changes and the sialographic features revealed a significant (P less than 0.001) correlation between raised filling pressure (greater than 60 mmHg) and the presence of an obstructive lesion (stricture, mucous plug, sialolith). Occasionally a raised filling pressure was observed although the associated sialography films were normal. The sensitivity of the technique was 86.4%. It is concluded that the monitoring of pressure changes occurring during sialography can alert the clinician to the presence of high filling pressure and may also provide additional evidence of obstructive changes within salivary glands.

Adolescent↗
PubMed1990

Heck's disease.

The clinical and histological findings in two adult caucasians with focal epithelial hyperplasia (Heck's disease) are described. The literature concerning this rare condition is reviewed.

Adult↗
PubMed1990

Oral medicine in practice: white patches.

The seventh article in this series deals with conditions of the oral mucosa which present as white patches. Although the majority of white patches are benign, certain lesions are associated with premalignancy or malignancy. Unfortunately, the presence of any sinister lesion cannot be assessed by clinical appearance and therefore accurate diagnosis (involving biopsy) is mandatory whenever there is uncertainty about the clinical diagnosis of an oral white patch.

Candidiasis, Oral↗
PubMed1990

Sensitivity reaction to the cinnamonaldehyde component of toothpaste.

Sixteen patients developed a variety of oral lesions following a change in the toothpaste they used. Mucosal biopsy demonstrated features consistent with application of a topical medicament and patch testing, towards the constituents of the toothpastes, indicated the flavouring agent cinnamonaldehyde as being the likely responsible agent. Avoidance of the implicated toothpastes resulted in a considerable improvement in clinical signs and symptoms, whereas rechallenge in ten patients resulted in recurrence of symptoms in eight patients. It is concluded that sensitivity to the cinnamonaldehyde constituent of certain toothpastes, although uncommon, should be considered as a possible aetiological factor in patients presenting with non-specific oral changes.

Cinnamomum zeylanicum↗
PubMed1990

Enhancement of interleukin-1 activity by murine cytomegalovirus infection of a macrophage cell line.

The effect of murine cytomegalovirus (MCMV) infection on interleukin 1 (IL-1) secretion was assessed using the macrophage cell lines P388D1 and J774A.1. The former proved to be nonpermissive for MCMV in that infectious virus and viral immediate early protein (pp89) were not expressed in these cells. MCMV infection of the P388D1 cells had no effect on release of biologically active IL-1. In contrast, J774A.1 cells, which were semipermissive for virus replication and pp89 expression, secreted enhanced levels of IL-1 activity following infection. The enhancement was evident when infection either preceded or followed lipopolysaccharide stimulation of the macrophages. The relative proportion of IL-1 alpha and beta secreted from MCMV-infected cells was similar to noninfected controls. In addition, the bioactivity of intracellular IL-1 alpha escaping membranes of fixed cells was unaffected by virus infection. From these findings, we conclude that limited MCMV expression in the J774A.1 macrophage cell line enhances secretion of IL-1 alpha and beta bioactivity.

Animals↗
PubMed1990

Chronic toxicities of surfactants and detergent builders to algae: a review and risk assessment.

Surfactants are high volume chemicals used primarily in detergent products and are found in natural waters. The toxic effects of representative surfactants on aquatic life have been determined and summarized in greater detail for animal test species than for aquatic vegetation. This paper summarizes the chronic toxicity levels for algae, an important trophic level in aquatic ecosystems. Toxic effects have been determined for a few commercially important surfactants and primarily for cultured freshwater algae under the controlled conditions of the laboratory where inhibition, and in some cases, stimulation have been observed. The reported toxicities of surfactants have varied widely over several orders of magnitude and the effect levels are compound and species-specific. Species sensitivity can vary as much as three orders of magnitude to the same surfactant and the effects of different surfactants on the same algal species can vary as much as four orders of magnitude. Therefore, data generalizations and extrapolations are difficult but anionic and nonionic surfactants and detergent builders are relatively non-toxic when compared to various cationic monoalkyl and dialkyl quaternary ammonium salts. Recent toxicity studies conducted in the field monitoring the effects of several surfactants used in commercial products on various structural and functional parameters of natural algal communities have shown toxicity to be less in many cases than that predicted from laboratory tests. Furthermore, the field-derived effect levels typically exceed the reported measured environmental levels of the corresponding surfactants indicating the likelihood of no impact. Additional field studies are needed to substantiate this trend for these and other commercially important surfactants particularly for natural saltwater algal assemblages for which the toxicity data base is unavailable.

Detergents↗
PubMed1990

A microbiological and clinical review of the acute dentoalveolar abscess.

Early microbiological studies of acute suppurative dental infection implicated streptococci or staphylococci as the causative microorganisms but recent studies suggest that the microbial flora of acute dentoalveolar abscess is usually polymicrobial, predominantly involving CO2-dependent streptococci, strictly anaerobic Gram-positive cocci and strictly anaerobic Gram-negative bacilli. These differences are probably due to poor sampling techniques and inadequate culture methods used in the early investigations. It is now accepted that specimens should be obtained by aspiration to avoid contamination and processed promptly using strict anaerobic culture. Traditionally the bacterial strains isolated have been regarded as members of the normal oral commensal microflora but it is becoming increasingly apparent from experimental infections that they have pathogenic properties. Although the vast majority of isolates have been found to be sensitive to a variety of antimicrobial agents there would not appear to be a uniformly effective drug. At the present time a penicillin, such as amoxycillin, would probably be the first choice antimicrobial agent with the addition of metronidazole if clinical improvement does not occur.

Acute Disease↗
PubMed1990

Social control, health risk taking, and psychological distress among the elderly.

Most research on older adults' social networks has focused on the support-providing function of social relationships. Little gerontological research has addressed social control, or the role of social bonds in regulating deviant or risky behavior. Drawing on sociological theory, this study examined the hypothesis that social control discourages risky health practices while provoking psychological distress. Structured interviews conducted with 162 community-residing older adults assessed social control (direct attempts by other to influence participants' health practices and the existence of significant role obligations to others), health risk taking (medication misuse, alcohol consumption, cigarette smoking, and the overall level of unsound health practices), psychological functioning (depression, loneliness, and self-esteem), and interpersonal satisfaction (satisfaction with friends and family members). Analyses revealed little support for the hypothesis. Social control was only weakly related to participants' health practices and, contrary to expectation, was generally related to less psychological distress and to greater interpersonal satisfaction. Implications for social control theory and for further research are addressed.

Adaptation, Psychological↗
PubMed1990

Access for peritoneal dialysis in neonates and infants.

A new catheter for peritoneal dialysis in neonates and infants was used on 28 occasions in 17 patients. Advantages over other catheters included easy safe introduction over a guide wire, absence of early leakage of dialysate, and the ability to change the catheter without creating a second abdominal wound.

Catheterization↗
PubMed1990

First nursing home admissions: time spent at home and in institutions after discharge.

We tracked 96 percent of a sample of 1,942 nursing home patients admitted to a nursing home for the first time in 1982-83. Patients discharged alive from the nursing home were followed for two years or until death. The relative time spent at home, in hospitals, and in skilled nursing facilities is reported. Of the 705 patients discharged from their initial nursing home admission to homes in the community, about 50 percent made only one transfer and only 15 percent made four or more transfers. Of the 509 discharged to a hospital, 26 percent died there and 37 percent of the 374 survivors made four or more moves in the next two years. In all, 1,332 patients were discharged alive and they spent almost two-thirds of the subsequent two years, or their remaining lifetimes, in the community. Of those who transferred only once, over two-thirds of their follow-up time was spent in their own homes. Policies concerned with long-term care should use some type of actuarial data base to successfully plan and implement long-term care insurance.

Humans↗
PubMed1990

Changes in case mix and outcomes of readmissions to nursing homes between 1980 and 1984.

This study compares the personal characteristics, measures of functional status/case mix, and immediate discharge outcomes of two cohorts of nursing home patients (1980 and 1984). All of these patients had a prior history of nursing home care and all were readmitted to skilled nursing facilities from hospitals. In 1984, readmissions were more disabled, more debilitated, and significantly less likely to return home. They were almost twice as likely to be rehospitalized within 30 days of discharge from the hospital (26.7 percent versus 48.9 percent). Analyses showed poorer health status and an increased proportion of nursing home deaths and rehospitalizations in the 1984 group to be a function of time (1984 versus 1980) rather than of insurance coverage (Medicare versus other). Nursing home readmissions appear to be quite sensitive to cost-containment efforts, and they may require additional hospital days to stabilize their conditions in an effort to reduce the rate of hospital readmissions and the overall cost of care.

Aged↗