Blood lactate accumulation decreases during the slow component of oxygen uptake without a decrease in muscular efficiency

Pulmonary oxygen uptake ([Formula: see text]) slowly increases during exercise above the anaerobic threshold, and this increase is called the slow component of [Formula: see text]. The mechanism of the increase in [Formula: see text] is assumed to be due to increasing energy cost associated with increasingly inefficient muscle contraction. We hypothesized that the increase in [Formula: see text] would be accompanied by a constant or increasing rate of accumulation of blood lactate, indicating sustained anaerobic metabolism while [Formula: see text] increased. Ten male subjects performed cycle ergometry for 3, 6, and 9 min at a power output representing 60% of the difference between lactate threshold and maximal [Formula: see text] while [Formula: see text] and blood lactate accumulation were measured. Blood lactate accumulation decreased over time, providing the energy equivalent of (mean ± SD) 1586 ± 265, 855 ± 287, and 431 ± 392 ml of [Formula: see text] during 0-3, 3-6, and 6-9 min of exercise, respectively. As duration progressed, [Formula: see text] supplied 86.3 ± 2.0, 93.6 ± 1.9, and 96.8 ± 2.9% of total energy from 0 to 3, 3 to 6, and 6 to 9 min, respectively, while anaerobic contribution decreased. There was no change in total energy cost after 3 min, except that required by ventilatory muscles for the progressive increase in ventilation. The slow component of [Formula: see text] is accompanied by decreasing anaerobic energy contribution beyond 3 min during heavy exercise.

Skeletal muscle-specific overproduction of constitutively activated c-Jun N-terminal kinase (JNK) induces insulin resistance in mice

AIMS/HYPOTHESIS

Although skeletal muscle insulin resistance has been associated with activation of c-Jun N-terminal kinase (JNK), whether increased JNK activity causes insulin resistance in this organ is not clear. In this study we examined the metabolic consequences of isolated JNK phosphorylation in muscle tissue.

METHODS

Plasmids containing genes encoding a wild-type JNK1 (WT-JNK) or a JNK1/JNKK2 fusion protein (rendering JNK constitutively active; CA-Jnk) were electroporated into one tibialis anterior (TA) muscle of C57Bl/6 mice, with the contralateral TA injected with an empty vector (CON) to serve as a within-animal control.

RESULTS

Overproduction of WT-JNK resulted in a modest (~25%) increase in phosphorylation (Thr(183)/Tyr(185)) of JNK, but no differences were observed in Ser(307) phosphorylation of insulin receptor substrate 1 (IRS-1) or total IRS-1 protein, nor in insulin-stimulated glucose clearance into the TA muscle when comparing WT-JNK with CON. By contrast, overexpression of CA-Jnk, which markedly increased the phosphorylation of CA-JNK, also increased serine phosphorylation of IRS-1, markedly decreased total IRS-1 protein, and decreased insulin-stimulated phosphorylation of the insulin receptor (Tyr(1361)) and phosphorylation of Akt at (Ser(473) and Thr(308)) compared with CON. Moreover, overexpression of CA-Jnk decreased insulin-stimulated glucose clearance into the TA muscle compared with CON and these effects were observed without changes in intramuscular lipid species.

CONCLUSIONS/INTERPRETATION

Constitutive activation of JNK in skeletal muscle impairs insulin signalling at the level of IRS-1 and Akt, a process which results in the disruption of normal glucose clearance into the muscle.

THE RECOVERY FROM PATIENTS WITH ACUTE PNEUMONITIS OF A VIRUS CAUSING PNEUMONIA IN THE MONGOOSE

1. A virus capable of producing pulmonary consolidation in the wild mongoose (Herpestes griseus) has been isolated from throat washings obtained from four patients with a clinical syndrome termed acute pneumonitis. 2. The virus was not pathogenic for ferrets, mice, guinea pigs, rabbits, monkeys, voles, hamsters, deer mice, skunks, opossums, or woodchucks. 3. The virus was filterable through Berkefeld V and N candles, was not inactivated by glycerin or by freezing and drying in vacuum, and was propagated for at least 30 serial passages on the chorio-allantoic membrane of the developing chick embryo. 4. Normal mongooses placed in contact with infected mongooses developed pulmonary consolidation. 5. The virus was neutralized by the serum of mongooses convalescent from the infection but was not neutralized by normal mongoose serum. 6. Serum of human beings convalescent from acute pneumonitis also neutralized the virus, but serum obtained from the same individuals during the acute phase of the disease failed to do so. 7. The evidence so far obtained strongly suggests that this virus is the cause of acute pneumonitis in human beings. It differs from other viruses known to cause infections of the respiratory tract in man.

Bacterial prostatitis: urine and spermatic fluid culture

To evaluate in a prospective study the sensitivity of urine and spermatic fluid cultures in identifying the presence of infection compared to Meares-Stamey's test (MSt) results. Fourty patients were diagnosed having bacterial prostatitis following MSt. They underwent both urine and spermatic fluid cultures after MSt results and immediately before antibiotic treatment. All the patients were asked which of the three examens was the least tolerable. Urine and spermatic fluid culture were negative in 36 and 4 cases respectively. Spermatic fluid culture identified infection in 36 out of 40 patients who underwent MSt (90%) and was more acceptable for the patients. Urine culture is a less accurate way of identifying the infective agent in prostatitis, compared to spermatic fluid culture. The latter procedure is similar to the MSt.

Terazosine and tamsulosin in non bacterial prostatitis: a randomized placebo-controlled study

Eighteen patients with inflammatory process of the prostate met criteria for the inclusion in the study: 1) non bacterial prostatitis; 2) no previous treatment. Then they were randomized into three groups as it follows: terazosine, tamsulosin and placebo. Alpha-blockers and placebo were given for two months, after which further uroflowmetry was performed. Symptom score was evaluated before and after treatment. Terazosine was effective in reducing TO (p = 0.01) as tamsulosin and placebo did not. Both terazosine (p = 0.034) and tamsulosin (p = 0.006) reduced max TQ as placebo did not. Symptom score significantly improved in patients receiving terazosine (p = 0.0002) and tamsulosin (p = 0.001) while insignificantly in whose receiving placebo.

Unilateral testicular microlithiasis

Testicular microlithiasis is a rare pathology which usually affects both testicles (less than 100 cases have been described in the literature), histologically characterized by numerous calcified deposits situated inside the seminiferous tubules, the diameter of which does not usually exceed 2 mm. The pathogenesis of the phenomenon is not completely clear; it has however been noted that there is a higher incidence in patients affected by cryptorchidism, subfertility, Klinefelter's syndrome and in particular those with testicular neoplasms, although the reason for this remains obscure. The case reported seems atypical in that there is no association with the conditions mentioned above and the finding is monolateral, something which is unusual in the literature reviewed.

Two atypical cases of renal leiomyosarcoma: clinical picture, diagnosis and therapy

The Authors report two cases of renal leiomyosarcomas with atypical clinical features. Despite a malignant histological picture, nephron-sparing surgery was performed. The two patients are alive and disease-free at six years and fifteen months respectively. Specific radiologic findings, indications and rationale for conservative treatment are discussed.