Chemical shift tensor determination using magnetically oriented microcrystal array (MOMA): 13C solid-state CP NMR without MAS.

Chemical shift tensors for the carboxyl and methyl carbons of L-alanine crystals were determined using a magnetically oriented microcrystal array (MOMA) prepared from a microcrystalline powder sample of L-alanine. A MOMA is a single-crystal-like composite in which microcrystals are aligned three-dimensionally in a matrix resin. The single-crystal rotation method was applied to the MOMA to determine the principal values and axes of the chemical shift tensors. The result showed good agreement with the literature data for the single crystal of L-alanine. This demonstrates that the present technique is a powerful tool for determining the chemical shift tensor of a crystal from a microcrystal powder sample.

A comparison of the effects of mezlocillin and carbenicillin on haemostasis in volunteers.

Mezlocillin and carbenicillin were administered intravenously to healthy male volunteers, for six days each, in a double-blind crossover study. Tests to detect abnormalities in haemostasis were performed before, during and after administration. Platelet aggregation studies indicated that both antibiotics interfered with platelet aggregation and secretion resulting in prolonged bleeding times. The effect was dose related and rapidly reversible after discontinuation of the antibiotics. It always occurred earlier and was more profound with carbenicillin than with mezlocillin (P = 0.008). Bleeding times greater than 15 min were observed in 17% of volunteers who received 18 g/day of mezlocillin and 83% of volunteers who received 18 g/day of carbenicillin (P less than 0.05). There were no abnormalities in the coagulation cascade. The risk of acquiring an antibiotic-induced clinical bleeding disorder is lower with mezlocillin than with carbenicillin.

Medical aspects of air travel.

Air travel is convenient but can exacerbate underlying medical conditions. Most problems can be related to changes in atmospheric pressure, hypoxia, air sickness and jet lag. International travelers should be counseled about traveler's diarrhea and malaria if they are flying to endemic areas. Pregnancy is not in itself a contraindication to flying. Common-sense recommendations and reassurance can help assuage concerns about prolonged air travel.

Pharmacokinetics of spectinomycin in volunteers with renal insufficiency.

The pharmacokinetics of spectinomycin hydrochloride after 2 g intravenous doses were studied in ten volunteers with varying degrees of renal function. Mean peak serum concentration in 8 volunteers with renal insufficiency was 150.9 +/- (SD) 42.3 microgram/ml which was similar to 2 normal volunteers who had concentrations of 139 and 186 microgram/ml. Serum half-lives in the volunteers with renal insufficiency ranged from 4.7 to 29.3 h and increased as creatinine clearance decreased. Serum half-lives of the 2 normal volunteers were 1.5 and 1.7 h. Urine concentrations and percents of recovery were variable.

Cerebrospinal fluid glucose and protein values in normal rabbits.

In 35 normal rabbits the cerebrospinal fluid glucose values ranged between 56 and 135 mg/dl, mean and standard deviation 78 +/- 13 mg/dl. Cerebrospinal total protein values ranged from 16 to 66 mg/dl, mean values were similar to those reported for human cerebrospinal fluid. Depression of the cerebrospinal glucose level in the rabbit may parallel the human situation and prove to be a useful marker of purulent inflammation.

A safe and simple technique for obtaining cerebrospinal fluid from rabbits.

A safe and simple method for obtaining cerebrospinal fluid from the anesthetized rabbit was accomplished by cannulating the fourth ventricle. Cerebrospinal fluid (1.5--2.0 ml) was obtained for laboratory analysis. The procedure could be repeated at 2--3 day intervals without detrimental effects.

Radionuclide liver spots: indicator of liver disease or a blood flow phenomenon.

Abnormal areas of increased uptake on liver scan have been controversial. While often said to be associated with superior vena caval obstruction, three distinctly different findings are possible: hot spot, warm spot, and no spot. All of these changes can be readily explained by distinct, separate anatomic venous collateral pathways. Four cases of superior vena caval obstruction with isotopic liver flow studies are presented. Anatomy of the venous collateral system is reviewed, and the potential significance of the liver "warm spot" is considered.