Heterogeneity of glomerular size in normal donor kidneys: impact of race

Glomerular size has been the subject of many studies and, in a number of settings, has a direct association with the development of glomerular sclerosis. However, the normal distribution of glomerular size has not been thoroughly evaluated in the general population in the United States. To address this issue, we analyzed the baseline biopsy specimens of 103 human donor kidneys to determine the maximal planar area (MPA) of the glomerular tuft in a heterogeneous human population. The MPA of each glomerulus was determined by measurement of sections through the vascular pole and/or origin of the proximal tubule, and was determined on each section by two methods: point counting and computer planimetry. There was very high agreement between these two methods. Multivariate analysis was used to identify significant correlates with MPA. Overall, younger donors had smaller glomeruli (P < 0.0001). Black donors had a larger MPA (23.4+/-8.6 mm2 x 10(-3)) than white donors (17.9+/-6.7 mm2 x 10(-3); P < 0.001), independent of donor age. MPA was not significantly different between genders. This heterogeneity in glomerular size may confound clinical studies if not recognized and may help explain differences in glomerular structure and function in response to injurious processes.     

The effect of nitrous oxide on in vitro fertilization success rate

The authors studied the effect of nitrous oxide on success rates for in vitro fertilization and pregnancy in women undergoing laparoscopy for oocyte retrieval. Ninety-eight patients in an in vitro fertilization program were randomly assigned to an anesthetic regimen including either 0.7% (end-tidal) isoflurane with 60% nitrous oxide in oxygen, or 1.4% (end-tidal) isoflurane in oxygen. Success rates for fertilization and pregnancy in 44 additional patients who declined randomization were also studied. Among the 51 randomized patients who did not receive nitrous oxide, 192 oocytes were obtained and 122 fertilized (63.5%), resulting in eight pregnancies (16.3%). From the 47 randomized patients given nitrous oxide, 168 oocytes were retrieved and 114 fertilized (67.9%), resulting in nine pregnancies (19.1%). No significant differences between rates of fertilization or pregnancy emerged between groups. Such differences would have been found with an 80% probability had nitrous oxide had a 20% effect on oocyte fertilization.     

DIFFICULTIES AND DILEMMAS IN THE MANAGEMENT OF CONGENITAL ANOMALIES IN TWIN PREGNANCY

Both the incidence of twin pregnancy and the demand for prenatal diagnosis are increasing. Unfortunately, biochemical screening and ultrasound scanning are less reliable for prenatal diagnosis in twin pregnancies than in singletons. Amniocentesis and chorionic villous biopsy are usually diagnostic in singleton pregnancies but may be marred by sampling errors in twin gestations. Where a congenital anomaly has been diagnosed in a twin pregnancy, difficult decisions may have to be made, especially if one twin is unaffected. In these cases, special skills are required to ensure that adequate information, psychological support and optimal medical care are provided.     

NMR characteristics of "visible" intracellular myocardial potassium in perfused rat hearts

Nuclear magnetic resonance (NMR) spectroscopy provides a unique view of ions through its noninvasive character and relaxation time measurements. Several previous studies have demonstrated that only approximately 20% of cardiac intracellular potassium is visible with current NMR techniques. This study investigates the NMR visible intracellular potassium in a perfused rat heart preparation. When shift reagents were used to separate the intra- and extracellular signals, an intracellular T1 of 11.8 +/- 0.6 ms, and an intracellular T2 with two time constants of 1.3 +/- 0.6 ms (33 +/- 8%) and 10.1 +/- 1.9 ms (67 +/- 4%) were measured. Curve stripping techniques used to separate the intra- and extracellular components of a bulk relaxation decay yielded an intracellular T1 of 8.4 +/- 0.3 ms and an intracellular T2 with two time constants of 1.1 +/- 0.6 ms (38 +/- 10%) and 8.0 +/- 1.6 ms (62 +/- 12%). These results demonstrate that there are at least two distinct pools of potassium within the cardiac cell in slow exchange with each other on the NMR time scale. Studies with an enriched 41K perfusate demonstrated that the exchange rate for the visible intra- and extracellular potassium is on the order of 15 min.     

Medical complications of eating disorders in adolescents

Anorexia nervosa and bulimia are occurring with increased frequency among adolescents and preadolescents. To determine the range and severity of medical complications encountered in younger anorectic and bulimic patients, we reviewed the medical records of 65 adolescents and preadolescents, aged 10 to 20 years, who were observed in the Eating Disorders Clinic of the Children's Hospital at Stanford. Significant medical instability was present in the majority of our patients. A total of 55% of anorectic patients and 22% of bulimic patients required hospitalization for medical reasons during the study period. Cardiovascular abnormalities were frequent, including bradycardia, prolonged corrected QT intervals, dysrhythmias, and marked orthostatic pulse and BP instability. Hypothermia, with temperatures less than 35.5 degrees C, was common. Renal abnormalities included pyuria, hematuria, and proteinuria. Electrolyte derangements occurred in patients who vomited or purged. Hypokalemia was most common, but hypocalcemia, hypomagnesemia, and hypophosphatemia were also noted. The majority of our pediatric patients with eating disorders had evidence of physiologic derangement requiring medical intervention. The need for adolescents and preadolescents with eating disorders to receive ongoing medical monitoring in concert with psychiatric treatment and the need for therapists and medical practitioners to become familiar with the potential medical sequelae of eating disorders are underscored by our data.