An ultrasound technique to measure placental growth in ewes

Changes in mean diameter of cotyledons were measured from day 45 to 141 of pregnancy using real time ultrasound on 40 3-6-year-old Merino ewes, averaging 46 kg liveweight at day 45, and carrying one foetus. Observations were made at about 2-weekly intervals. Half of the ewes were sacrificed at day 94 and the remainder at day 141 to correlate the observations taken during pregnancy with actual data. There was a significant quadratic relationship (P < 0.001) between mean cotyledon diameter and a square root transformation of day of pregnancy. Maximum diameter of the cotyledons, as estimated by real time ultrasound, occurred at the observation on day 80 of pregnancy. The between-ewe comparison of mean diameter of the cotyledons measured by ultrasound just prior to slaughter with actual mean diameter recorded at slaughter showed a significant correlation (P < 0.001) for both the day 94 (r = 0.69) and day 141 (r = 0.71) results. Within ewes, the correlation between diameter and weight of the cotyledon was high (0.92, 0.86 for days 94 and 141 respectively), and the slope of the linear regression was less (P < 0.001) on day 141 than day 94 (0.45 v 0.32). Eighty-three per cent of the variation between ewes in total weight of cotyledons on day 94 of pregnancy was accounted for by a regression using sex of foetus, number of cotyledons and mean diameter of cotyledons measured by ultrasound on day 80 of pregnancy. In comparison, for day 141 of pregnancy 49% of the variation between ewes in total weight of cotyledons was accounted for by a regression using mean diameter on day 66 of pregnancy and number of cotyledons. The technique has potential value in studying patterns of development of the cotyledons during pregnancy in the ewe, but further validation is necessary.

The role of folylpolyglutamate synthetase and gamma-glutamyl hydrolase in altering cellular folyl- and antifolylpolyglutamates

The metabolic products of methotrexate differ in hepatocytes and hepatoma cells; the primary products are 7-hydroxymethotrexate in hepatocytes and the polyglutamate derivatives in hepatoma cells. The rate of glutamylation is approximately 5-fold greater in hepatoma cells than hepatocytes under comparable conditions and the polyglutamate products in the hepatoma cells consist of longer chain length tri- and tetraglutamate derivatives, whereas the hepatocytes favor the diglutamate derivative. Extracts of cultured hepatocytes have approximately half the folylpolyglutamate synthetase and three times as much gamma-glutamyl hydrolase as the hepatoma cells. A further difference is that methionine inhibits glutamylation in hepatocytes whereas it can cause a marked stimulation (five- to seven-fold) in hepatoma cells. The rate of glutamylation of methotrexate in intact hepatoma cells is strongly dependent on the culture conditions and can be enhanced as much as five-fold in dividing cultures or by removing folates from the cells. These changes may be in part caused by the fact that the folylpolyglutamate synthetase is nearly doubled in both growing cultures and in folate lacking cells. The treatment of human liver in vivo or rodent hepatic cells in vivo and in vitro with methotrexate causes a reduction in the folate pools. Data presented in these studies show that the activity of gamma-glutamyl hydrolase in cells can be enhanced by prior exposure to methotrexate. Thus, methotrexate could cause a loss in cellular folylpolyglutamates by enhancing their rate of cleavage to folylmonoglutamates.

Metal chelates as urographic contrast agents for magnetic resonance imaging. A comparative study

Paramagnetic metal chelates including Fe-EDTA, Fe-CDTA, Fe-DTPA, and Gd-DTPA were compared as intravenous urographic contrast agents for magnetic resonance (MR) imaging in rats. Each compound, administered intravenously at three different doses (0.05, 0.1, and 0.2 mmol./kg.), was rapidly excreted through the kidneys yielding renal signal enhancement between 5 min. and 50 min. after injection. Gd-DTPA was most effective vor the enhancement of the renal parenchyma and pelvis. Lesser enhancement was achieved by administration of Fe-CDTA followed by Fe-EDTA and Fe-DTPA. Enhancement of skeletal muscle and liver parenchyma could not be achieved with any of the compounds included in this study. We conclude that the iron chelates mentioned above are less effective as urographic agents for MR imaging than Gd-DTPA.

Neurohumoral activation during exercise in congestive heart failure

Neurohumoral factors were assessed in 14 subjects with chronic, stable New York Heart Association functional class II or III congestive heart failure and nine comparably aged normal subjects at rest and during moderate (50 W) and strenuous (100 W) upright exercise. Heart failure was associated with elevated plasma renin activity and plasma antidiuretic hormone (ADH) concentrations at rest. However, plasma renin activity almost doubled (from 4.7 +/- 0.6 to 8.4 +/- 1.1 ng/ml per hour) during strenuous exercise in subjects with heart failure, and changed only minimally in normal control subjects. Plasma ADH concentration did not change during exercise in the presence of heart failure, but rose in normal subjects during strenuous exercise to levels comparable to those of subjects with heart failure. Similar plasma osmolality values were present in both groups. Circulating norepinephrine concentrations were insignificantly elevated by heart failure both at rest and during exercise, and plasma epinephrine concentrations were similar. These findings suggest independent neurohumoral activation during exercise in the presence of congestive heart failure, with predominant activation of the renin-angiotensin-aldosterone axis.

A study of dynamic load balancing in a distributed system

This paper presents a study of a distributed system consisting of a number of hosts connected by a local area network. The system model is based on the LOCUS distributed file system. The LOCUS file system allows replicated files, and the synchronization policy is enforced by the use of the Centralized Synchronization Sites (CSS). All requests to open a file for access must be sent to the file's CSS which checks for access conflicts. Our simulation model allows process migration. The focus of this study is on load balancing as applied to optimal process and read site placement. An algorithm is proposed that increases system performance through load balancing. This algorithm uses data collected by the system on which to base its decisions. The characteristics of the algorithm and their effects on system performance are analyzed and discussed.

Potential methods for predicting tumor radiocurability

Several predictors of tumor radiocurability are already integrated into clinical practice, for example, tumor size, gross morphology (that is, infiltrative or exophytic), histologic type and grade. These are nonspecific and relatively imprecise. The aim of research into predictive assays is not only to refine the discrimination of existing predictors, but also to suggest specific experimental approaches for overcoming tumor radioresistance in individual patients. Two broad categories of predictive assays can be defined: direct and indirect measurement of tumor cell survival and/or repair capability following irradiation, and measurement of cellular and extracellular parameters affecting radiosensitivity. The ongoing research at The University of Texas M. D. Anderson Hospital is overviewed to illustrate potential methods for predicting radiocurability.

Alcohol and drug use among "street" adolescents

Studies of adolescent alcohol use typically sample intact high school populations. This study assessed "street" adolescents alienated from the mainstream educational system. Despite recent optimism regarding adolescent substance use, these respondents showed considerable alcohol consumption, drinking to get drunk, and problems. The major correlates of substance abuse were "personal" drinking motives, expectancies of alcohol effects and peer behavior. Thus, adolescents who would not appear in typical studies showed much stronger alcohol involvement than the general population, with individual differences best accounted for by attitude variables relevant to a "stress-vulnerability" approach to substance abuse.

Detection of an abdominal aneurysm by indium-111 platelet imaging

The authors report a case in which In-111 platelet imaging provided uniquely useful information in the discovery of an abdominal aortic aneurysm. This case illustrates the potential usefulness of this procedure in the detection of unsuspected sites of thrombogenic vascular disease.

Evaluation of right subphrenic fluid collections with emission computed tomography: an experimental study

An animal model to study subphrenic fluid collections is presented. Performance of single photon emission computed tomography (SPECT) for detection of subphrenic fluid collections was compared to that of liver-lung scintigraphy and transmission computed tomography (TCT). TCT detected a water volume of 25 ml in the right subphrenic space. This volume was barely seen using SPECT and not detectable on scintigraphy. Differences in performance of the three imaging modalities are discussed.

Predicting radiocurability

Several predictors of tumor radiocurability are already integrated into clinical practice, e.g., tumor size, gross morphologic features (i.e., infiltrative or exophytic), histologic type, and grade. These are relatively imprecise, however, and none is specific. The aim of research into predictive assays is not only to refine the discrimination of existing predictors but also to suggest specific experimental approaches for overcoming tumor radioresistance in individual patients. Two broad categories of predictive assays can be defined: direct and indirect measurements of tumor cell survival and/or repair capability following irradiation and measurement of cellular and extracellular parameters affecting radiosensitivity. Examples from ongoing research at the University of Texas M. D. Anderson Hospital using one technique from each category (the micronucleus assay and flow cytometric analysis of tumor cell proliferation kinetics and ploidy) are used to illustrate potential methods of selecting patients for fast neutron radiotherapy.

Nasal carriage and antibiotic susceptibility of Staphylococcus aureus in general practice

The incidence of nasal carriage of Staphylococcus aureus and the in vitro susceptibility of isolates to fusidic acid, penicillin, erythromycin, methicillin and tetracycline was determined in 204 patients who had been treated previously with a short course of a topical preparation of Fucidin for acute skin sepsis, and in an equal number of control subjects. Staphylococcus aureus was isolated from 36 per cent and 34 per cent of patients in the Fucidin and control groups respectively. Only one of the 144 isolates was resistant to fusidic acid. Short, single courses of topical therapy in general practice are unlikely to be epidemiologically hazardous in the long term. Evidence of possible cross-infection in general practice was obtained.

Venous pressures during simulated Bier's block

Venous pressures in the forearm veins during the simulated performance of intravenous regional analgesia were measured. Pressures obtained equalled or exceeded the recommended occluding pressure of the tourniquet. This finding is proposed as one of the possible reasons for the occasional observation that convulsions may occur during Bier's block despite the presence of an intact tourniquet system.

Methylprednisolone sodium succinate (Solu-Medrol) in the treatment of typhoid perforation (a preliminary report)

It is now universally accepted that treatment of typhoid perforation must be surgical. In spite of this and the use of antibiotics, the mortality rate is still high. Previous observations that some patients with typhoid perforation present with features suggestive of septicaemia and septic shock made us conduct a clinical trial with methylprednisolone sodium succinate (Solu-Medrol) in treating this disease. Our data show that use of this drug in addition to antibiotics and early surgical intervention reduces the mortality rate in typhoid perforation.