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F Vawda

Publications and source records attributed to F Vawda.

7 recordsLinked to original sources
PubMed2006

Comparison of plain chest radiography and high-resolution CT in human immunodeficiency virus infected patients with community-acquired pneumonia: a sub-Saharan Africa study.

The objective of the study was to determine the proportion of patients with missed lesions on plain chest radiographs compared with high-resolution computed tomography (HRCT) in 49 human immunodeficiency virus (HIV) infected patients with community-acquired pneumonia (CAP). Patients underwent plain chest radiography and HRCT scans of the chest at admission. Microbiological investigations for CAP were performed. An experienced radiologist, without knowledge of clinical or pathological data, reported the chest radiographs and HRCT scans. The study group included 26 females and 23 males, aged 18-53 years (mean age 36 years). Organisms were isolated from 26 patients (53%). In 40 patients (82%), the HRCT scans demonstrated lesions not visualized on the plain chest radiographs. There was 100% correlation between plain radiographic and HRCT scan findings in nine cases (18%). Lesions that were not visualized on the plain radiographs but elucidated on HRCT included: pleural effusion (n = 14), ground-glass opacification (n = 20), pericardial effusion (n = 8), cavitation (n = 4), cysts (n = 4), bullae (n = 4), abscess (n = 1) and pneumothorax (n = 1). In 20 of 23 cases, hilar lymphadenopathy, identified on HRCT, was not recognized on plain chest radiographs. In patients in whom an organism was isolated, a correct HRCT diagnosis of pulmonary tuberculosis, bacterial pneumonia and Pneumocystis carinii pneumonia (PCP) was made in 80%, 84% and 100% of cases, respectively. The proportion of patients with missed lesions on plain chest radiographs in HIV infected patients with CAP was high. This has important implications for management and prognosis. HRCT scans correlate well with the microbiological diagnosis when reported by an experienced radiologist.

Adolescent↗
PubMed2005

Ventriculitis due to a hetero strain of vancomycin intermediate Staphylococcus aureus (hVISA): successful treatment with linezolid in combination with intraventricular vancomycin.

A 67-year male presented with relapse 14 days after treatment with vancomycin for a MRSA ventriculitis. CSF samples taken at the time of relapse grew MRSA with a MIC for vancomycin of 4 mg/L by E-test and therapy with linezolid (600 mg bd) and intraventricular vancomycin (20 mg od) was initiated. Using the macrodilution E-test, the isolate was found to have sub-populations with a MIC for vancomycin of 8 mg/L and teicoplanin of 12 mg/L and a population analysis profile almost identical to the hVISA strain MU3, indicative of a hVISA strain. Concentrations of vancomycin in the CSF over the period of therapy ranged from 25.6-192.5 mg/L after intraventricular administration and those of linezolid ranged from 3.4-6.7 mg/L after intravenous administration, exceeding the MICs for this isolate. The patient made a successful recovery, with no further episodes of ventriculitis at 1-year follow-up. We report the first case of ventriculitis due to hVISA. It was successfully treated with intrathecal vancomycin and intravenous linezolid. We also believe this to be the first documented case of clinical infection due to hVISA in South Africa.

Acetamides↗
PubMed1999

Force generation upon hydrostatic pressure release in tetanized intact frog muscle fibres.

Single intact muscle fibres isolated from the tibialis anterior muscle of the frog were exposed to hydrostatic pressures of 1-10 MPa, at 2-4 degrees C and sarcomere length of 2.1-2.2 microm. The pressure was rapidly released (ca. 1 ms) to atmospheric level (0.1 MPa) during the plateau of a tetanic contraction (Po) and the resultant tension (= force) transient examined. The pressure release induced tension transient consisted of an initial tension drop coincident with pressure release (ca. 4% Po per MPa, Phase 1), followed by a rapid recovery (Phase 2a) and a slower rise of tension (Phase 2b). Phase 1 was partly due to a length release at fibre ends (ca. 0.1 nm per half-sarcomere per MPa) induced by pressure-release effects on the steel chamber and fibre attachments, and partly due to 'expansion' upon pressure release within muscle fibre (ca. 0.2 nm per half-sarcomere per MPa), probably in the myofilaments and cross-bridges. The rate of tension recovery during phase 2a (ca. 600/s) was comparable to that of the quick tension recovery (T1-T2 transition) reported from moderately fast small length releases; the time course of Phase 2b (rate ca. 40/s) was similar to the late phase of tension rise in a tetanus, and hence compared with Phase 4 (T4) of a length release tension transient. Results are compared with the previously reported findings from analogous experiments on Ca2+ -activated skinned (rabbit) muscle fibres.

Animals↗
PubMed1996

Effects of hydrostatic pressure on fatiguing frog muscle fibres.

Effects of increased hydrostatic pressure (range 0.1-10 MPa) on isometric twitch and tetanic contractions of single, intact, frog muscle fibres were examined at 4, 11 and 21 degrees C and at different stages of fatigue. Twitch tension was potentiated by pressure at all temperatures, but the extent of potentiation was more pronounced at higher temperatures (34% MPa-1 at 21 degrees C, compared to 8% MPa-1 at 4 degrees C). Tetanic tension was depressed by pressure at 4 degrees C (approximately 0.7% MPa-1) but was potentiated by pressure at 21 degrees C (approximately 0.4% MPa-1). The effect of hydrostatic pressure on the tetanic tension was dependent on the fatigue status of the muscle fibre: during the early stages of fatigue (when tetanic tension was depressed by < 20%), high pressure produced a tension depression (as in an unfatigued muscle fibre), whilst during the later stages of fatigue high pressure induced a significant potentiation of tetanic. Our results support the suggestion that excitation-contraction coupling and contractile activation are impaired during late fatigue. Pressure-effects were basically similar to caffeine-effects under a variety of conditions, suggesting that an enhancement of Ca2+ release may be contributory to potentiation of twitch tension and, in severely, fatigued muscle, potentiation of tetanic tension. In the rested state and during early fatigue the main effect of pressure is an inhibition of the crossbridge cycle.

Animals↗
PubMed1995

Pressure-induced changes in the isometric contractions of single intact frog muscle fibres at low temperatures.

Effects of increased hydrostatic pressure (range 0.1-10 MPa) on isometric twitch and tetanic contractions of single intact muscle fibres, isolated from frog tibialis anterior muscle, were examined at 4-12 degrees C. The tension changes produced on exposure to steady high pressures are compared with those produced on exposure to low concentrations of caffeine (0.5 mM, subthreshold for contracture) and when pressure is rapidly released during a contraction. The peak twitch tension was potentiated by pressure accompanied by increased rate of tension rise and increased duration; the pressure sensitivity of twitch tension was approximately 8% MPa-1. The correlation between the rate of tension rise and peak tension in caffeine-induced twitch tension potentiation was quantitatively similar to that in pressure-induced twitch potentiation. Experiments involving the rapid release of pressure (approximately 2 ms) during twitch contractions demonstrate that high pressure need only be maintained for a brief period during the early part of tension development to elicit full twitch potentiation. The tetanic tension was depressed by pressure (approximately 1% MPa-1). Results demonstrate that the major effect of increased hydrostatic pressure on intact muscle fibres, which results in tension potentiation, is complete very early during contraction and is similar to that of caffeine.

Animals↗