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%.     

Fluorescein angiographic findings in three patients with long-term intravitreal liquid silicone.

The long-term retinal effects of intravitreal liquid silicone (ILS) remain controversial. In this study fundus fluorescein angiographic findings in three patients with long-term ILS are presented. Sluggish or absent blood flow was observed in retinal arterioles that lay in close proximity to the ILS, and the arterioles themselves appeared narrowed. It is suggested that ILS may have a long-term effect on the retinal vasculature, owing either to direct vascular damage, secondary to damage to the neuroretina, or to the ILS preventing diffusion of oxygen into the vitreous cavity.     

Functional correlates of verbal memory deficits emerging during nicotine withdrawal in abstinent adolescent cannabis users.

BACKGROUND: Cannabis remains the most widely used illicit substance by adolescents and is typically consumed by this population in the context of ongoing tobacco use. Human studies have shown that both cannabis and tobacco exert effects on cognitive function; however, little is known about possible interacting effects of these drugs on brain function and cognition during adolescent development. METHODS: Verbal learning and memory were assessed in 20 adolescent users of tobacco and cannabis and 25 adolescent tobacco users with minimal history of cannabis use. Functional magnetic resonance imaging was used to examine brain function and functional connectivity while a subset of these subjects performed a verbal working memory task. RESULTS: Delayed recall of verbal stimuli deteriorated during nicotine withdrawal among cannabis users but not among comparison subjects. During high verbal working memory load, nicotine withdrawal selectively increased task-related activation of posterior cortical regions and was associated with disruption of frontoparietal connectivity in adolescent cannabis users relative to comparison subjects. CONCLUSIONS: These observations suggest that cannabis use during adolescent development may disrupt neurocircuitry supporting verbal memory formation and that deficits associated with disruption of these neurocircuits are unmasked during nicotine withdrawal.     

Trachoma: 1985 update in Western Australia

Aboriginal preschool and school children were surveyed in the Eastern Goldfields Region and the Eastern Kimberley Region of Western Australia between 1979 and 1985. Statistics from these surveys show that there has been an apparent change in pattern of follicular trachoma since the National Trachoma and Eye Health Programme in some of the communities. The prevalence of follicular trachoma in the 0 to 9 year old age groups had declined from 26.4% in 1977 to 8.8% in 1984/1985 in the Eastern Goldfields and Red Centre combined (0.10 greater than p greater than 0.05). The prevalence reduction occurred in areas where there have been improvements in school hygiene and housing. The prevalence of cicatricial trachoma has also apparently declined from 65% in 1977 to 39% in 1985 in the Red Centre, from 39% in 1977 in the Eastern Goldfields to 21.7% in 1985, and from 58% in 1977 to 24.9% in 1985 in the Eastern Kimberley, Communities at risk were identified and recommendations made for frequency of continued screening, depending on age, distribution and location.     

The physician's role in an aging America: taking the team approach to eldercare

With the advent of an aging patient population, the healthcare community is sharpening its focus on geriatric medicine and on how current resources will fare under the demands of an aging America. One approach to effective eldercare is that of a "team" of physician and nonphysician providers, cooperating to meet the multifaceted needs of the elderly patient. As the traditional primary care provider, the physician is a natural choice for the role of team leader.