Non-linear intestinal absorption kinetics of cefadroxil in the rat

Absorption of cefadroxil in a selective intestinal absorption area (the proximal third of the small intestine) of the anaesthetized rat, at seven initial perfusion concentrations, ranging from 0.01 to 10.0 mg mL-1, is shown to be a non-linear transport mechanism. With the aid of computer-fitting procedures based on differential and integrated forms of Michaelis-Menten equation, Vm and Km values of 36.7-37.3 mg h-1 and 12.0-13.0 mg, respectively, were found. The statistical parameters were better than those obtained both for first-order and for combined Michaelis-Menten and first-order kinetics. There is no evidence for substantial passive diffusion processes. The results reported here, together with allometric considerations and literature data analysis, may help to explain some particular non-linear features of plasma level curves associated with the administration of fairly high oral doses of cefadroxil to humans.     

Contractile properties of in situ perfused skeletal muscles from rats with congestive heart failure

We hypothesized that in congestive heart failure (CHF) slow-twitch but not fast-twitch muscles exhibit decreased fatigue resistance in the sense of accelerated reduction of muscle force during activity. Experiments were carried out on anaesthetized rats 6 weeks after induction of myocardial infarction or a sham operation (Sham). Animals with left ventricular end-diastolic pressure (LVEDP) > 15 mmHg under anaesthesia were selected for the CHF group. There was no muscle atrophy in CHF. Force generation by in situ perfused soleus (Sol) or extensor digitorum longus (EDL) muscles was recorded during stimulation (trains at 5 Hz for 6 s (Sol) or 10 Hz for 1.5 s (EDL) at 10 or 2.5 s intervals, respectively) for 1 h in Sol and 10 min in EDL at 37 °C. Initial force was almost the same in Sol from CHF and Sham rats, but relaxation was slower in CHF. Relaxation times (95–5 % of peak force) were 177 ± 55 and 131 ± 44 ms in CHF and Sham, respectively, following the first stimulation train. After 2 min of stimulation the muscles transiently became slower and maximum relaxation times were 264 ± 71 and 220 ± 45 ms in CHF and Sham, respectively (   P < 0.05  ). After 60 min they recovered to 204 ± 60 and 122 ± 55 ms in CHF and Sham, respectively (   P < 0.05  ). In CHF but not in Sham rats the force of contraction of Sol declined from the second to the sixtieth minute to 70 % of peak force. The EDL of both CHF and Sham fatigued to 24–28 % of initial force, but no differences in contractility pattern were detected. Thus, slow-twitch muscle is severely affected in CHF by slower than normal relaxation and significantly reduced fatigue resistance, which may explain the sensation of both muscle stiffness and fatigue in CHF patients.     

Relationship between digestive and killing abilities of neutrophils against Paracoccidioides brasiliensis.

Peripheral blood neutrophils (PMN) from patients with paracoccidioidomycosis killed and digested Paracoccidioides brasiliensis much less than did PMN from normal individuals or from patients with other diseases. However, deficiency in killing ability was less specific than digestive deficiency and correlated poorly with it. We conclude that the capacities of PMN to digest and kill P. brasiliensis are not intimately related phenomena, and that in paracoccidioidomycosis the key deficiency of neutrophil function is that of digestion of P. brasiliensis.     

Tissue characterization of symptomatic and asymptomatic disc herniations by quantitative magnetic resonance imaging

The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T₁ and T₂ relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T₁ and T₂, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T₁ and T₂ relaxation times. Symptomatic disc herniations exhibited significantly (p_T1 < 0.04 and p_T2 < 0.003) shorter T₁(ΔT₁:–182.1 milliseconds, ?15%) and T₂(ΔT₂: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition.     

Aortic valve replacement by a pulmonary homograft

Minor experience still exists in our country with regard to the use of valve homografts in cardiac surgery. Only a few implantations have been performed in cases of right ventricular outflow tract reconstruction in addition to our own experience in cases of infective endocarditis of the aortic valve. We present a case of aortic valve replacement by using an antibiotic-sterilized fresh pulmonary valve autograft. The case is described and the possible advantages of the use of pulmonary allografts in the aortic position are discussed.     

Use of a commercial double-test tablet (Rosco PGUA/indole) for screening of Escherichia coli.

A commercial double-test tablet (Rosco PGUA/indole) for detection of beta-glucuronidase (beta-GUR) activity and indole production was evaluated on a collection of 393 isolates of Enterobacteria. Both beta-GUR and indole were positive on 96.6% of Escherichia coli strains. beta-GUR, only, was also detected in 25 Shigella spp., four Enterobacter cloacae, eight Citrobacter freundii, and five Salmonella enteritidis strains, none of which were indole producers. An additional 261 consecutive clinical isolates of oxidase-negative nonswarming Gram-negative bacilli were studied in a parallel comparative field trial against conventional identification methods. For 200 strains, the standard method and PGUA/indole test were performed from the primary culture plate. The remaining 61 (23.4%) required subculture before testing. Sensitivity, specificity, positive predictive value, and negative predictive value of PGUA/indole test in the screening for E. coli were, respectively, 94.1%, 100%, 100%, and 87.1%. In our experience, PGUA/indole test is a rapid, precise, simple-to-perform, and economical method for screening E. coli. However, the need for a large inoculum may limit its application on primary cultures.     

Susceptibility to endometrial cancer: influence of allelism at p53, glutathione S-transferase (GSTM1 and GSTT1) and cytochrome P-450 (CYP1A1) loci.

A case-control study was designed to identify associations between polymorphisms at p53, cytochrome P-450 (CYP1A1) and glutathione-S-transferases and endometrial cancer susceptibility. Among all polymorphisms analysed, an insertional variant in p53 (P53PIN3) and two polymorphisms in the 3''-end and exon 7 of CYP1A1 showed significant association with enhanced endometrial cancer risk.