Hypohydration effects on skeletal muscle performance and metabolism: a 31P-MRS study

The purpose of this study was to determine whether hypohydration reduces skeletal muscle endurance and whether increased H+ and Pi might contribute to performance degradation. Ten physically active volunteers (age 21-40 yr) performed supine single-leg, knee-extension exercise to exhaustion in a 1.5-T whole body magnetic resonance spectroscopy (MRS) system when euhydrated and when hypohydrated (4% body wt). 31P spectra were collected at a rate of one per second at rest, exercise, and recovery, and were grouped and averaged to represent 10-s intervals. The desired hydration level was achieved by having the subjects perform 2-3 h of exercise in a warm room (40 degrees C dry bulb, 20% relative humidity) with or without fluid replacement 3-8 h before the experiment. Time to fatigue was reduced (P < 0.05) by 15% when the subjects were hypohydrated [213 +/- 12 vs. 251 +/- 15 (SE) s]. Muscle strength was generally not affected by hypohydration. Muscle pH and Pi/beta-ATP ratio were similar during exercise and at exhaustion, regardless of hydration state. The time constants for phosphocreatine recovery were also similar between trials. In summary, moderate hypohydration reduces muscle endurance, and neither H+ nor Pi concentration appears to be related to these reductions.     

Expression of aquaporin-4 in fast-twitch fibers of mammalian skeletal muscle

OBJECT: Ependymomas in children continue to generate controversy regarding their histological diagnosis and grading. optimal management, and possible prognostic factors. To increase our knowledge of these tumors the authors addressed these issues in a cohort of children with prospectively staged ependymomas treated with radiotherapy and chemotherapy. METHODS: Children between the ages of 2 and 17.3 years harboring an intracranial ependymoma confirmed by a central review of the tumor's pathological characteristics were treated according to Children's Cancer Group Protocol 921 from 1986 to 1992. Treatment following surgery and postoperative tumor staging (including brain computerized tomography or magnetic resonance [MR] imaging, spinal MR imaging or myelography, and cerebrospinal fluid cytological investigation) included craniospinal irradiation with a local boost to the primary tumor and patient randomization to receive adjuvant chemotherapy with either 1) CCNU, vincristine, and prednisone, or 2) the eight-drugs-in-1-day regimen. Centralized review of the tumor pathological characteristics revealed 20 ependymomas and 12 anaplastic ependymomas in the 32 children included in the study. Diagnoses made at the individual institutions included anaplastic (malignant) ependymoma (15 patients), ependymoma (four patients), ependymoblastoma (nine patients), ependymoastrocytoma (one patient), and primitive neuroectodermal tumor (three patients), which were discordant with the centralized review diagnosis in 22 of 32 cases. Only three of the 32 patients had metastatic disease (two with M and one with M3 stages). At surgery, 47% of tumors were estimated to be totally resected. Among the 14 of 17 patients who suffered a relapse and were evaluated for site of relapse, 10 (71%) had an isolated local relapse, three (21%) had concurrent local and metastatic relapse, and only one (7%) had an isolated metastatic relapse. Kaplan-Meier estimates of 5-year progression-free survival (PFS) and overall survival rates were 50 +/- 10% and 64 +/- 9%, respectively. CONCLUSIONS: Predictors of PFS duration included an estimate of the extent of resection made at surgery (total compared with less than total, p = 0.0001) and the amount of residual tumor on postoperative imaging as verified by centralized radiological review (< or = 1.5 cm2 compared with > 1.5 cm2, p < 0.0001). No other factors, including centrally reviewed tumor histopathological type, location, metastasis and tumor (M and T) stages, patient age, race, gender, or chemotherapy treatment regimen significantly correlated with PFS duration. The pattern of predominantly local relapse and the important influence of residual tumor or the extent of resection on PFS duration confirms a prevailing impression that local disease control is the major factor in the prediction of outcome of ependymoma. Survival rates were comparable with those reported by other investigators who have treated patients with similar doses of radiation and no chemotherapy.     

Does 'intestinal angina' exist? A critical study of obstructed visceral arteries

A study of the mesenteric arteries was carried out in 203 unselected autopsies. Although mild degrees of stenosis were common, the incidence of a 'critical stenosis' was rare and no correlation between degrees of stenosis and previous gastrointestinal symptoms could be found. Radiological demonstration of stenosed or blocked visceral arteries remains therefore of doubtful clinical significance.     

Retrograde gastric mucosal prolapse as a cause of haematemesis

Three cases of haematemesis associated with alcohol abuse are described. Early fibreoptic endoscopical examination in each showed a focal, well demarcated area of gastric mucosal haemorrhage, close to the oesophagogastric junction. Two patients showed prolapse of the lesion into the lower part of the oesophagus, and the third had coexistent Mallory-Weiss tears. Our observations suggest that forceful vomiting is responsible for this lesion, by causing abrupt retrograde gastrooesophageal prolapse. The prognosis of the lesion appears good.     

Allosteric interactions between the membrane-bound acetylcholine receptor and chemical mediators: equilibrium measurements

An approach to equilibrium dialysis measurements has been developed which enables one to study the interaction of chemical mediators with the membrane-bound acetylcholine receptor and to gain information of a type previously obtainable only with soluble proteins. Equilibrium dialysis experiments conducted at pH 7.0,4 degrees C, and mu = 0.18 M, with electroplax membrane preparations from Electrophorus electricus revealed apparently homogeneous binding isotherms for decamethonium with dissociation constants in the range of 0.2-0.4 muM. The following new information has been obtained. (1) The activators of neural transmission, decamethonium and carbamylcholine, occupy overlapping binding sites. (2) These activators and the inhibitors, alpha-bungarotoxin and d-tubocurarine, compete for only one-half of the sites available to them even through the stoichiometry of these is 1:1 as measured with decamethonium (a reversibly binding activator) and alpha-bungarotoxin (an irreversible specific inhibitor). Different receptor molecules, preexisting nonequivalent binding sites, or an allosteric mechanism involving ligand-induced conformational changes are often considered to account for such observations.     

Phase I studies with Baker's Antifol (BAF) (NSC 139105)

Phase I studies were conducted in 58 adult cancer patients with Baker's Antifol (BAF), a new active-site directed inhibitor of dihydrofolate reductase. Dose escalation ranged from 10 to 250 mg/m2/day X 5 days and courses of treatment were repeated every 2-3 weeks. Biologic effects were observed mostly at doses greater than 100 mg/m2/day X 5 days. The patients developed myelosuppression during 19% of the trials. Other types of toxicity were dermatitis in 12 to 30% and stomatitis in 7 to 38% of the trials. Toxicity was directly related to the impairment of the patient's liver function. Two partial responses (in a patient with adenocarcinoma of the lung and a patient with transitional cell carcinoma of the bladder) occurred. BAF is an active new chemotherapeutic agent which deserves further clinical trials in patients with various malignancies.     

A ten year study of medullary carcinoma of the breast

In this large series of patients treated for medullary carcinoma of the breast by radical mastectomy, the over-all five year survival rate was 63.7 per cent and the ten year survival rate, 49.5 per cent. Although survival was adversely affected by axillary lymph node involvement, there was an equal incidence of such involvement, there was an equal incidence of such involvement in tumors less than 4 centimeters compared with those greater than 4 centimeters in size; however, patients with tumors greater than 4 centimeters in size fared poorer categorically than did those with smaller lesions. Women in the premenopausal period had one-third of the cancers and had a significantly better survival rate than did those in the postmenopausal period, despite a similar incidence of axillary lymph node involvement. Medullary carcinoma is among the small group of malignant tumors of the breast that have distinctly better five and ten year survival rates than other more common varieties.