Comparisons of air and liquid personal cooling for intermittent heavy work in moderate temperatures.

Personal microenvironmental cooling has been used to enhance safety and extend the work capacity of laborers wearing protective clothing. Previous studies of air and liquid cooling have used either very low work rates or high environmental temperatures. Emergency work tasks frequently require high work rates and occur in moderate ambient temperatures. The purpose of this research was to examine the efficacy of intermittent personal cooling during rest and to compare liquid and air cooling systems in subjects engaged in hard work. Fourteen volunteers wearing chemical protective clothing performed treadmill walking at a metabolic rate of 430 W for 45 min followed by a 15-min rest at a wet-bulb globe temperature of 25 degrees C. During rest, volunteers received either no cooling, air cooling, or liquid cooling. Both cooling systems partially alleviated heat strain and increased work time with the air system offering slightly more effective cooling.     

Distribution and disposition of trospectomycin sulfate in the in vivo rat, perfused rat liver, and cultured rat hepatocytes

Trospectomycin sulfate is an experimental, aminocyclitol antibiotic. It has been shown in preclinical, chronic safety studies in the dog and rat to elicit a reversible, lysosomal phospholipidosis in liver. The present experiments were conducted to characterize the tissue distribution and disposition of 3H]trospectomycin sulfate in the male rat, perfused rat, perfused rat liver, and cultured rat hepatocytes. Following a 5 mg/kg iv dose to four rats, approximately 70% of the dose was recovered within 24 hr primarily in urine as unchanged drug, and the remainder was eliminated with a terminal phase half-life in blood and tissues of 3 days. Fecal excretion was relatively minor (16% of the dose recovered in feces in 7 days) until later timepoints, when it was the principal pathway of terminal phase elimination. The liver sequestered approximately 10% of the dose and had the highest tissue levels of drug at all times measured. Liver perfusion experiments indicated that trospectomycin accumulated in a hepatic depot compartment as parent drug by a first-order process which was nonsaturable up to a 1 mM concentration of drug. Biliary excretion of unchanged trospectomycin by the perfused liver was slow (approximately 3% of the dose in 2 hr) and occurred by both paracellular and transcellular mechanisms. The hepatic depot compartment appeared to be responsible for transcellular biliary excretion, and thus for the sustained fecal excretion observed in vivo. Subcellular distribution experiments indicated that at least 50% of the drug in the hepatic depot was sequestered in organelles having a broad density range. The existence of a trospectomycin depot compartment was also demonstrated in cultured hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Signal-to-noise and contrast in fast spin echo (FSE) and inversion recovery FSE imaging.

Fast spin echo (FSE) imaging has recently experienced a renewed enthusiasm in the clinical setting for its ability to provide high contrast T2-weighted images in short imaging times. This article evaluates the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) properties of the FSE sequence, inversion recovery (IR) FSE sequence, and conventional SE imaging. The results indicate that FSE imaging displays similar contrast properties to SE imaging, but that the SNR and CNR are improved secondary to the longer TRs and longer effective TEs that may be used. The SNR per unit time of the FSE sequence, and hence its efficiency, is at least a factor of 8 better than the SE sequence when 16 echoes are acquired for each excitation. The addition of a slice selective inversion pulse in IR-FSE allows rapid generation of IR images with image contrast similar to that of conventional IR sequences. When used with a multicoil array for abdominal, pelvic, and spine imaging, the IR-FSE sequence produces images that are virtually free of motion artifact from the subcutaneous fat immediately adjacent to the coils. Both FSE and IR-FSE, when compared with SE imaging, provide superior image contrast and SNR in reduced imaging time.     

The role of definitive radiation therapy in squamous cell carcinoma of the oral tongue

Between 1968 and 1985, 114 patients with squamous cell carcinoma of the tongue were evaluated in the Department of Radiation Oncology at the University of Virginia (Charlottesville, VA); of these, 86 received treatment with curative intent. The majority were treated with radiation therapy alone, whereas the remainder were treated with radiation therapy with preoperative or postoperative surgery. There were 17 T1 primary malignancies, 40 T2, 27 T3, and 2 T4. Clinically positive adenopathy was present in 48% of the patients overall and ranged from 35% in the T1 group to 100% in the T4 group. Twenty-six percent of patients either presented with or later had second malignancies. At 36 months, the patient status was evaluated as dead of disease (37%), dead of intercurrent disease (23%), alive with disease (1%), and alive without evidence of disease (38%). Seventy-five patients received external beam therapy and 32 patients received an implant as either all or part of their treatment. Average doses were in the range of 6000 Gy. Adjusted local control rate at 3 years was not statistically different for different treatment techniques used on either T1 or T2 primary malignancies. The rates were 89% versus 88% for T1 lesions treated with definitive radiation therapy versus postoperative radiation therapy. For T2 primary malignancies, the rates were 67%, 71%, and 83% for the definitive, preoperative, and postoperative radiation therapy groups, respectively. For T3 lesions, there was close to statistical significance with the corresponding rates being 47%, 50%, and 100%, respectively. When the effect of implants was examined for T1 and T2 lesions, no difference in local control rate at 3 years was noticed with or without an implant. Survival was improved for the group presenting with positive neck disease when compared with the N0 group. The external beam severe complication rate was less than 5%, and the implant complication rate was 6%.