Effects of increased ventilation and improved pulmonary gas-exchange on maximal oxygen uptake and power output

Recent reports suggest that aerobic performance at very high levels may be limited by the pulmonary system. The purpose of the present study was to compare respiratory functions at rest and during graded maximal aerobic exercise (cycle ergometry) between well-trained (TR, n = 11) and untrained (UT, n = 14) individuals while breathing atmospheric air, normoxic helium (He) and oxygen-enriched mixture. When the subjects breathed air, TR exhibited lower exercise ventilatory reserve (MVV-VE_max), ratio between minute ventilation (VE) and oxygen uptake (V_o2) and SaO₂ than UT. Breathing HE resulted in an increase in VE and V_o2max in both groups but in an increased VE/V_o2 and SaO₂ and maximal mechanical cycle ergometer load, only in TR. Compared with air, breathing an oxygen-enriched mixture resulted in increased peak exercise SaO₂ and maximal mechanical load in both groups. It is concluded that arterial O₂ desaturation secondary to a relative hypoventilatory response may limit V_o2max and aerobic performance capacity at high work levels.     

Energy metabolism in kidney of heat-acclimated hamsters.

Biochemical pathways which are involved in energy metabolism were examined in the kidney of heat-acclimated hamsters. It was found that heat acclimation caused 47% reduction in glucose-6-phosphatase (G1c-6-Pase) activity and 40% lower rate of gluconeogenesis. No changes were found in the activity of hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase, lactic dehydrogenase, or in kidney glycogen content. Isolated kidney mitochondria of heat-acclimated hamsters utilized 15% less oxygen than that of controls, but no differences were found in the P/O ratio. Determination of the content of some cytochromes showed a significant reduction in cytochromes c + c1, but no difference was found in the content of cytochromes a, a3, and b. These results suggest that the kidney plays a role in the reduction of energy metabolism during the process of heat acclimation.     

Fluidity difference in the surface membrane lipid core of human lymphoblastoid and lymphoma cell lines

Twenty-five human hematopoietic cell lines established from patients with malignant and non-malignant diseases have been studied for membrane fluidity. The degree of fluidity in the surface membranes was quantitatively monitored by fluorescence polarization analysis of the fluorescence probe, 1,6-diphenyl 1,3,5-hexatriene, when embedded in the lipid region of the surface membrane of intact cells. The results have shown that cells derived from malignant diseases have a more fluid lipid layer in their surface membrane than cells derived from non-malignant disorders. It is, therefore, suggested that a quantitative analysis of fluidity differences in the cell surface membrane lipid core can be of value to the studies on basic differences between normal and malignant cell lines established from the human hematopoietic system.     

Torsion of the cryptorchid testis--can it be salvaged?

PURPOSE: The literature concerning undescended testis mainly concentrates on the increased risks of infertility and development of germ cell tumors. Yet the UDT also appears to be at higher risk for torsion compared to the normally descended testis, and this issue is relatively poorly addressed. We reviewed all cases of torsion of UDTs operated on at our hospital during the last 20 years in an attempt to characterize better this condition and its salvageability. MATERIALS AND METHODS: In this retrospective clinical study we reviewed and analyzed all cases of testicular torsion involving UDT operated on at our hospital between 1984 and 2004. RESULTS: A total of 11 children were operated on at our hospital for torsion of undescended testis between 1984 and 2004. Patient age ranged from 1 month to 18 years (median 7.5 months). In all cases unilateral torsion of undescended testis was diagnosed, with 73% of cases involving the left side. Clinical symptoms included inguinal swelling and erythema associated with a tender, firm mass palpated in the groin area and an empty ipsilateral hemiscrotum. Doppler ultrasound examination was routinely performed in the last 7 patients to confirm the diagnosis. During inguinoscrotal exploration severe ischemia or overt necrosis of the testis was found in 5 of 11 cases. Three of these 5 cases were managed by orchiectomy, while in the other 2 cases the testis subsequently vanished. In the 6 patients who exhibited some improvement following detorsion and warming of the tissue the testes were preserved and orchiopexy was performed. Followup was available in only 5 patients, with vanishing of the torsed testis observed in 4 and a normal testicle detected 21 years postoperatively in 1 patient who was diagnosed early. CONCLUSIONS: This series clearly demonstrates poor rates of surgical salvage, which we mainly attribute to delays in parental response and in primary physician referral to the hospital. Parents, who have a pivotal role in early diagnosis, were usually unaware of this urological emergency, and some were surprisingly unaware of the presence of cryptorchidism. By increasing the awareness regarding this entity among members of the medical community and parents, we hope that torsion of the cryptorchid testis (literally, "hidden testis") will no longer necessarily be synonymous with "crypt-torsion" ("hidden torsion").     

The psychological profile and affective response of women diagnosed with unexplained infertility undergoing in vitro fertilization

It has been hypothesized that unexplained infertility may be related to specific personality and coping styles. We studied two groups of women with explained infertility (EIF, n?=?63) and unexplained infertility (UIF, n?=?42) undergoing an in vitro fertilization (IVF) cycle. Women completed personality and coping style questionnaires prior to the onset of the cycle, and state depression and anxiety scales before and at two additional time points during the cycle. Almost no in-between group differences were found at any of the measured time points in regards to the Minnesota Multiphasic Personality Inventory-2 validity and clinical scales, Illness Cognitions and Life Orientation Test, or for the situational measures. The few differences found suggest a more adaptive, better coping, and functioning defensive system in women with EIF. In conclusion, we did not find any clinically significant personality differences or differences in depression or anxiety levels between women with EIF and UIF during an IVF cycle. Minor differences found are probably a reaction to the ambiguous medical situation with its uncertain prognosis, amplifying certain traits which are not specific to one psychological structure but rather to the common experience shared by the group. The results of this study do not support the possibility that personality traits are involved in the pathophysiology of unexplained infertility.     

Thoracic sympathectomy and cardiopulmonary responses to exercise

The purpose was to study the effect of endoscopic thoracic sympathectomy (ETS) for palmar and/or axillary hyperhidrosis on physiological responses at rest, and during sub-maximal and maximal exercise in ten healthy patients (7 females and 3 males 18-40 years old) with idiopathic palmar and/or axillary hyperhidrosis. T2-T3 thoracoscopic sympathectomy was performed using a simplified one stage bilateral procedure. Physiological variables were recorded at rest and during sub-maximal (steady-state) and maximal treadmill exercise immediately prior to and 70 days (+/-7.5, SD) after bilateral ETS. Exercise performance capacity and peak VO(2) were not found to be different following bilateral ETS than prior to the ETS. However, heart rate was significantly reduced at rest (14%), at sub-maximal exercise (12.3%), and at peak exercise (5.7%), together with a significant increase in oxygen pulse (11.8, 12.7, and 7.8%, respectively). The rate pressure product (RPP) was also significantly reduced following the surgical procedure at all three study stages, while all other physiological variables measured remained unchanged. It is suggested that thoracic-sympathetic denervation affects the heart, sweating, and circulation of the respective denervated region but does not affect exercise performance or mechanical/physiologic efficiency, despite a significant reduction in heart rate (both at rest and during exercise). The latter was, most likely, fully compensated by an increase in stroke volume and less likely by an improved muscle O(2) extraction due to more efficient blood distribution, keeping the work-rate and oxygen uptake unaffected.     

Microcephaly-thin corpus callosum syndrome maps to 8q23.2-q24.12

Postnatal microcephaly is defined as normal head circumference at birth, which progressively declines to more than 2 standard deviations below the average for the patient's age and sex. We describe four patients from three consanguineous families of Arab Bedouin origin who presented with autosomal recessive inheritance of progressive microcephaly, spasticity, thin corpus callosum, pyramidal signs, and intellectual disability. Homozygosity mapping (Human Mapping NspI 250K arrays, Affymetrix, Santa Clara, CA) placed the disease locus at 8q23.2-q24.12. The candidate region includes 22 known or predicted genes, including RAD21, which is related to the cohesion complex EIF3H, which is involved in translation initiation, and TAF2, which may be involved in intellectual disability. Identification of the causative gene in our reported family will shed light on the pathogenesis of this severe condition.