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Biomedical subjects

K Johns

Publications and source records attributed to K Johns.

30 records · Page 2Linked to original sources
PubMed1991

Intraocular tumor from disseminated histoplasmosis.

We identified and treated a solid, growing fungal tumor mass in a patient with disseminated histoplasmosis. Although the most commonly reported intraocular lesions from disseminated histoplasmosis are areas of inactive chorioretinal scars or areas of localized subretinal neovascular membrane formation, a focus of active fungal growth needs to be ruled out in all such cases. When a solid tumor mass is identified, the most effective way of preserving vision is with systemic antifungal therapy.

Amphotericin B↗
PubMed1990

Late pulmonary allergic responses in actively but not passively IgE-sensitized rats.

Previous studies suggested that although rats that were passively sensitized [monoclonal murine immunoglobulin E (IgE)] would respond to pulmonary antigen challenge with an immediate increase in resistance, they exhibited no late increases in resistance, unlike late changes in rats actively sensitized to preferentially produce IgE antibody. We hypothesized that passively sensitized rats also would not develop antigen-induced pulmonary inflammation. In a blinded protocol we compared immediate responses and pulmonary resistance and inflammation at 8, 19 and 24 h after challenge with placebo antigen, with dinitrophenol-bovine serum albumin (DNP-BSA) to elicit a passively sensitized response, or with ovalbumin (OA) to elicit an actively sensitized response. Despite similar immediate responses to OA and DNP-BSA, only the rats challenged with OA had marked inflammatory changes and a significant incidence of late elevations in resistance. Inflammation scores and lung resistance were significantly correlated only in the OA group. We also observed that anesthesia with fentanyl/droperidol significantly attenuated the immediate but not the late responses to antigen challenge, compared with rats anesthetized with ketamine. We conclude that IgE-mediated immediate responses to pulmonary antigen challenge are insufficient, and may be unnecessary, to initiate antigen-induced late inflammatory changes.

Airway Resistance↗
PubMed1990

Contribution of upper airways to antigen-induced late airway obstructive responses in guinea pigs.

The pathogenesis of the late asthmatic response has been of interest due to the fact that its development has been associated with airway obstruction, airway inflammation, and airway hyperresponsiveness: all features of chronic asthma. In order to study more precisely late responses, a number of animal models have been developed. Previous reports have described alterations in airway mechanics at both 3 to 6 and 17 h after antigen challenge in sensitized guinea pigs. In these experiments, however, animals were challenged through the nose with aerosolized antigen, and airway conductance was measured using whole body plethysmography while the animals breathed through the upper airways. In rats similarly challenged, the predominant immediate change in resistance occurs in the upper airways. The purpose of this study, therefore, was to evaluate the contribution made by both the upper and lower airways to late changes after allergen challenge in guinea pigs. Outbred female Hartley guinea pigs were actively or passively sensitized (IgG1 antibody response) to three different antigens and challenged either by direct tracheal insufflation (sheep gamma globulin [SGG] or oxazolone-human serum albumin [OX-HSA]) or by aerosolization (ovalbumin [OA]). Lung resistance (RL) and dynamic compliance (Cdyn) were measured in anesthetized guinea pigs through a tracheostomy tube, and specific airway conductance (SGaw) was measured in unanesthetized, nose-breathing guinea pigs using a whole body plethysmograph. Late responses were defined as a RL greater than the mean + 2 SD RL or as a decrease in SGaw from baseline greater than 2 SD from the placebo-challenged (bovine serum albumin) group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Cardiorespiratory and hemodynamic responses to inversion and inversion with sit-ups.

Eighteen men were studied during 15 minutes of inversion to determine the effects of 4 sit-ups per minute for 5 minutes on the cardiorespiratory system. Systolic blood pressure, diastolic blood pressure, ventilation, oxygen uptake, and METS increased significantly from preinversion/standing (A) to inversion (B). Arterial blood pressure increased from 122/81 mmHg to 142/99 mmHg during the first 5 minutes of inversion. Oxygen uptake increased from 341 ml.min-1 to 456 ml.min-1. Heart rate decreased significantly from (A) to (B). Double product, frequency of breaths, and tidal volume were not significantly changed from (A) to (B). Blood pressure, double product, ventilation, frequency of breaths, oxygen uptake, and METS increased significantly from the first 5 minutes of inversion (B) to the second 5 minutes of inversion with sit-ups (C). Arterial blood pressure increased from 142/99 mmHg (B) to 163/104 mmHg (C). The diastolic value remained significantly increased following the muscle strengthening exercise. Double product increased from 104 (B) to 126 (C), and oxygen uptake increased from 456 ml.min-1 (B) to 565 ml.min-1 (C). Following inversion/sit-ups (C), oxygen uptake decreased significantly during the third 5 minutes of inversion (D). Systolic blood pressure was also significantly decreased at (D) following the sit-ups. Upon returning to the standing position (E) versus the third 5 minutes of inversion (D), arterial blood pressure decreased significantly from 151/108 mmHg (D) to 123/84 mmHg (E). The postinversion/standing (E) blood pressure was nonsignificantly different from the preinversion/standing (A) blood pressure as was also the case with heart rate, double product, and tidal volume. Ventilation, frequency of breaths, oxygen uptake, and METS were still significantly increased during (E) versus (A). These data illustrate the influence of muscular exercise on the cardiorespiratory system during full -90 degree inversion. The increase in blood pressure is no cause for concern, and the assumed dangerous effects of full inversion have been overestimated.

Adolescent↗
PubMed1986

Magnetic resonance imaging of the brain in isolated optic neuritis.

Magnetic resonance imaging of the brain was performed on ten patients who had isolated optic neuritis. Seven patients had abnormal images, with a distribution of lesions similar to that seen in multiple sclerosis, demonstrating subclinical dissemination in the central nervous system.

Adolescent↗
PubMed1985

Chorioretinal and choriovitreal neovascularization after photocoagulation for proliferative diabetic retinopathy. A clinicopathologic correlation.

A patient with proliferative diabetic retinopathy was treated by panretinal and focal photocoagulation. Later, he developed one area of clinically diagnosed chorioretinal and choriovitreal neovascularization (CNV), neovascular glaucoma, and a blind painful eye necessitating enucleation. Clinicopathologic correlations of this eye including fundus photography, fluorescein angiography, light and electron microscopy are reported. Histopathologic examination revealed three areas of CNV, suggesting that some CNV may go undetected clinically also in other cases and thus may occur more frequently than evident from the literature. Our CNV occurred at sites of focal treatment. Retreatment of one area was unsuccessful. Choriovitreal neovascularization passed through discontinuities of Bruch's membrane into the retina and showed fenestrae of the endothelial cells. Endothelial fenestrae may account for the profuse fluorescein leakage seen clinically in CNV.

Adult↗
PubMedDate not supplied

Clinical experience with combination disease-modifying antirheumatic drug therapy with cyclosporine.

OBJECTIVES: We previously reported on the clinical use of cyclosporine (Neoral), alone or in combination with methotrexate (MTX), in the first 46 refractory rheumatoid arthritis (RA) patients treated at our centre between March 1996 and November 1997. Thirty of the 46 patients remained on cyclosporine at study completion (mean dose 2.98 mg/kg/day) with efficacy inferred by significant reductions in the prednisolone and MTX doses and creatinine maintained in an acceptable range. Early discontinuation was primarily related to non-serious side effects. METHODS: The 30 patients continuing cyclosporine were reviewed 12 months later in November 1998. Analysis included life-table techniques. RESULTS: 21 of the original 46 patients (46%) continued at a mean dose of 2.59 mg/kg/day after a mean of 23.4 months. Nine patients discontinued cyclosporine during this 12-month period: 3 due to inactive disease, 2 due to hypertension, 2 due to elevated creatinine, and 1 due to mononeuritis multiplex secondary to rheumatoid vasculitis, and 1 due to inefficacy. Patients continuing cyclosporine had a shorter disease duration (9.85 versus 15.5 years [P = 0.05]). The prednisolone dose decreased from a baseline value of 10.57 mg/day to 6.78 mg/day (P = 0.007) and the MTX dose from 15.6 mg/week to 13.1 mg/week (P = 0.02). The mean serum creatinine level increased from a baseline of 73.86 mumol/l to 85.8 mumol/l (16%). 21/30 patients on combination therapy with MTX showed no difference in discontinuation rates compared with those on cyclosporine alone. Life-table analysis showed a bimodal distribution with significantly increased cyclosporine discontinuation in the first 12 months (principally due to non-renal/hypertensive causes) versus the subsequent period. CONCLUSION: This follow-up study indicates that the use of cyclosporine in refractory RA allows a reduction in the prednisolone and MTX doses. Utilization is longer in earlier disease and is unaffected by combination with MTX. Renal function is maintained within an acceptable range. The bimodal discontinuation curve reflects early patient/physician concern about minor side effects, while renal/hypertension changes resulted in later discontinuation.

Antirheumatic Agents↗