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Biomedical subjects

J M Lyons

Publications and source records attributed to J M Lyons.

At least 37 records · Page 2Linked to original sources
PubMed1990

Variation in virulence among oculogenital serovars of Chlamydia trachomatis in experimental genital tract infection.

Seven different oculogenital serovars (D, E, F, G, H, I, and K) of Chlamydia trachomatis were inoculated intravaginally into CF-1 mice, and subsequent infection was monitored. The duration of infection was longest with serovars D and E. This may help to explain clinical surveys which demonstrate a high (50%) prevalence of these serovars. Furthermore, a comparison of the invasiveness of strains D and H demonstrated a much higher frequency of uterine horn infection with serovar D.

Animals↗
PubMed1986

Proximal muscle weakness and selenium deficiency associated with long term parenteral nutrition.

A 33-yr-old white female with short bowel syndrome secondary to trauma was maintained on home parenteral nutrition for 4 yr when her plasma, red cell, white cell, and platelet glutathione peroxidase (GSHPx) activities were found to be extremely low, as were her plasma and red cell selenium levels. During her first year on parenteral nutrition she noted the onset of an inability to rise from a squatting position, rapid tiring when stair climbing, and weakness when attempting to lift large or moderately heavy objects. Treatment with 400 micrograms/d of selenious acid intravenously was associated with a disappearance of her symptoms and an increase in proximal muscle strength within 6 wk. The plasma and red cell selenium levels, and the plasma and white cell GSHPx activities rose to normal levels within 6 wk. Red cell GSHPx activity returned to normal by 3 mo.

Adult↗
PubMed1986

Inductive coupling of hearing aids and telephone receivers.

The present investigation sought to determine the effects of hearing loss, signal level, telephone receiver type, and telecoil location on the aided word-discrimination abilities of hearing impaired subjects using electromagnetic coupling of their hearing aids to the telephone. As expected, significant deterioration in discrimination scores was observed with increasing hearing loss. In addition, significant improvement in discrimination scores was observed, for all subject groups, as the signal level increased from 80 dB SPL to 105 dB SPL. Of the four receiver conditions, the U1 and BARC receivers resulted in the best discrimination scores. Also, the results suggest that the U1 and BARC receivers are indeed equivalent in terms of word discrimination scores. Finally, the telecoil location in individual hearing aids appeared to have little influence on the speech discrimination capabilities of the subjects in this study. However caution must be used in interpreting that result, since subjects were allowed to adjust the telephone handset position to maximize the signal level in any given condition. This occasionally resulted in inappropriate handset locations for conventional telephone use.

Activities of Daily Living↗
PubMed1985

Chylous ascites in infants and children: a case report and literature review.

Successful treatment of an infant with chylous ascites secondary to "congenital leaky lymphatics" is described, followed by a literature review of cases of pediatric chylous ascites. The infant was placed on home total parenteral nutrition for 10 weeks, during which time the chylous ascites resolved and did not recur with the introduction of a normal diet. Forty cases of pediatric chylous ascites have been reported since 1960, with an age range from birth to 18 years. The presenting signs and symptoms were secondary to abdominal distension in over 80% of cases. The chylous ascites was secondary to trauma, which included child abuse (19%), obstruction (27%), or lymphatic abnormalities (54%). Most studies described were not helpful in making the diagnosis, except for lymphangiography and exploratory laparotomy. Many patients were treated with a high-protein, low-fat diet, with or without medium-chain triglycerides, with variable success. Total parenteral nutrition (TPN) was the primary therapeutic modality in five patients, and in all but one of the cases there was complete resolution of the chylous ascites over 3 to 10 weeks with no significant side effects. Total parenteral nutrition, including home TPN, is a safe and effective therapeutic modality for some cases of chylous ascites.

Adolescent↗
PubMed1984

Specific cross-protective antigonococcal immunity in the murine genital tract.

Specific acquired immunity to gonococci was studied in systemically immunized mice, challenged with 10(7) gonococci by intrauterine inoculation. Protection after intraperitoneal immunization was monitored by vaginal cultures taken 24 h post-challenge, since events during the first 24 h postexposure to gonococci are crucial in determining the outcome of infection. Mice were protected against gonococcal challenge by two inoculations with either live or boiled gonococci given 4 weeks apart, whereas immunization with one inoculation did not protect against challenge 1 week later. Protection was correlated with high titers of IgG antibody in serum after two immunizations, but not with the high titers of serum IgM antibody found after the one immunization. IgG antibodies, but not IgM antibodies, were shown to pass into genital secretions. Protection could be passively transferred by serum with high titers of antibody. Of most practical importance was the finding that not only were heat-stable antigens protective, but also heterologous protection resulted after immunization with three strains differing in source (disseminated gonococcal infection versus gonorrhea), opacity-transparency characteristics, and serum sensitivity. The data indicate that IgG antibodies resulting from systemic immunization with heat-stable antigens may be able to provide cross-protection immunity against gonorrhea.

Animals↗
PubMed1979

Synergism of ampicillin and gentamicin against obstructive pyelonephritis due to Escherichia coli in rats.

Rats with obstructive pyelonephritis due to Escherichia coli were treated for different intervals with ampicillin and gentamicin either alone or in combination. The combination of ampicillin and gentamicin was synergistic in vitro and significantly more effective in vivo than was either drug alone. After treatment for 10 days, the combination of ampicillin and gentamicin was the only regimen that sterilized all of the pyelonephritic kidneys. The importance of achieving sterility was illustrated by the observation that severe infection and acute pyelonephritis recurred after religation of the ureter in 12 (71%) of 17 ampicillin-treated animals that had harbored as few as 46 organisms per kidney before ligation. A synergistic combination of antibiotics rapidly sterilizes obstructed pyelonephritic kidneys. In view of the particular risk of renal infection in the presence of urinary obstruction in humans, synergistic antibiotic combinations may be useful in the treatment of obstructive pyelonephritis in humans.

Acute Disease↗
PubMed1979

Prevention of pyelonephritis due to Escherichia coli in rats with gentamicin stored in kidney tissue.

Although gentamicin is known to accumulate and persist in the kidneys after systemic administration, its antibacterial activity at this site has not been determined. In the present study the accumulation of gentamicin in rat kidneys before infection prevented obstructive pyelonephritis due to Escherichia coli despite heavy urinary tract infection on the obstructed pelvis; thus the kidneys were protected against infection in the absence of effective levels of gentamicin in the urine. Stored gentamicin also protected pyelonephritic rats from relapse after complete obstruction of the kidneys. The level of antimicrobial activity of gentamicin in whole kidney tissue was 95% less than that anticipated on the basis of levels measured after dilution of kidney tissue homogenates; this low level of activity apparently was due in part to high concentrations of solutes. In view of these results in rats, the possibility must be considered that despite reduced activity, gentamicin storage might be useful in the prophylaxis of kidney infection in patients with abnormalities of the urinary tract. In the treatment of established kidney infection, the dose of gentamicin could be reduced and the interval of its administration increased for minimal toxicity.

Ampicillin↗
PubMed1978

Prevention of chronic experimental pyelonephritis by suppression of acute suppuration.

In order to evaluate the importance of suppuration, persistent infection, and scar formation in the evolution of Escherichia coli chronic pyelonephritis, we treated rats with different antibiotic regimens at different stages of the disease. The results show that (a) if acute suppurative pyelonephritis is aborted with early antibiotic therapy, chronic pyelonephritis is prevented; (b) chronic pyelonephritis can develop even after eradication of infection if acute suppuration persists beyond 3 days; (c) persistent infection does not lead to chronic pyelonephritis, if the acute suppuration is suppressed; and (d) residual infection, antigen-load, antibody, and(or) cell-dependent autoimmune processes did not play a significant role. We interpret these results as evidence that the pathologic entity recognized as chronic pyelonephritis results from kidney damage, scarring and shrinkage secondary to acute suppuration.

Acute Disease↗
PubMed1977

Immunization against retrograde pyelonephritis. III. Vaccination against chronic pyelonephritis due to Escherichia coli.

Vaccination with formalin-treated cells of Escherichia coli serotype O6 protected against unilateral retrograde pyelonephritis due to E. coli O6 in rats with partial ureteral obstruction. This protection was manifested not only by less parenchymal destruction and shrinkage of the pyelonephritic left kidney, but also by less secondary pyelonephritis and compensatory hypertrophy in the opposite right kidney. Vaccinated rats eliminated E. coli from the kidney more rapidly, but even when infection persisted in the kidney, the chronic pyelonephritis was less severe in vaccinated rats. High levels of antibody to E. coli lipopolysaccharide were found in vaccinated animals and may have contributed to protection. These results raise the question of whether vaccination ought to be considered for patients predisposed to chronic bacterial pyelonephritis.

Animals↗
PubMed1977

In vitro lysis of target cells by rat polymorphonuclear leukocytes isolated from acute pyelonephritic exudates.

Polymorphonuclear (PMN) leukocytes from acute pyelonephritic exudates of rats were examined for cytoxicity against various target cells. Pyelonephritic PMN leukocytes caused lysis in vitro of syngeneic renal epithelial cells in 24 to 48 hr. They also caused lysis of allogeneic and xenogeneic target cells. The susceptibility to PMN-induced cytolysis was different among various target cell lines. Cell lysis proceeded at low ratios of effector to target cells and was not dependent on the addition of antibody or lectins. PMN isolated from peritoneal exudates (starch or endotoxin induced) were also cytoxic for the target cells. Cell-free supernatants from pyelonephritic PMN-target cell mixtures, or pyelonephritic PMN leukocytes cultured alone contained cytolytic substances which were nondialyzable and heat stable Finally, the urine of pyelonephritic rats was cytotoxic. These results suggest that PMN leukocytes and their cytotoxic mediators are directly involved in the pathogenesis of renal injury in pyelonephritis.

Animals↗
PubMed1976

In vivo modification of plant membrane phospholipid composition.

Tomato seedlings treated with ethanolamine showed altered phospholipid composition. The changes included altered acyl chain composition as well as changes in the relative amounts of the phospholipid classes. Specifically, there was an increase in phosphatidylethanolamine and phosphatidylserine with a concomitant decrease in phosphatidylcholine and no overall increase in phospholipids. Treatment with ethanolamine increased the relative amount of C18 acyl chains (especially 18 : 2) in phosphatidylethanolamine and phosphatidylcholine at the expense of 16 : 0 and 16 : 1. Acyl composition of other phospholipid classes were unchanged. Labeled ethanolamine was incorporated mostly into phosphatidylethanolamine and phosphatidylcholine. Ethanolamine-stimulated incorporation of labeled oleate was entirely into acyl chains and appeared only as 18 : 1 and 18 : 2. There was greater incorporation, but less conversion of 18 : 1 to 18 : 2 with choline. Stearate was incorporated but desaturated.

Cell Membrane↗
PubMed1976

Cellular immunity in pyelonephritis: identification of suppressor cell activity of spleen cells in response to concanavalin A and inhibition of lymphocyte-mediated L cell cytotoxicity.

A population of fast sedimenting spleen cells was identified as the cause of impaired in vitro response of spleen cells to concanavalin A (Con A) in acute pyelonephritis in rats. These fast-sedimenting cells responded to Con A by suppressing the DNA synthetic response of normal spleen cells to Con A. In addition, spleen cells from acute pyelonephritis rats were significantly less able to mediate in vitro cell destruction in xenogeneic aggressor lymphocyte: target L cell mixtures. On the basis of these findings, the hypothesis is proposed that a suppressor cell can protect the pyelonephritic kidney against immunologically mediated tissue damage.

Animals↗
PubMed1974

Temperature-induced Phase Changes in the Membranes of Glyoxysomes, Mitochondria, and Proplastids from Germinating Castor Bean Endosperm.

Sucrose-gradient purified mitochondria, glyoxysomes, and proplastids from germinating castor bean (Ricinus communis L.) endosperm were examined by electron-spin resonance spectroscopy. A temperature-induced phase change was demonstrated in all of these organelles, their derivative membranes, and in micelles formed from the membrane phospholipids. The apparent transition temperature of the membrane lipids varied slightly between the samples, but in all cases, fell within the temperature range around 10 C where physiological and biochemical changes in the response to temperature for most chilling-sensitive plants occur.

Journal Article↗