An universal model of health and work output: theoretical structure and testing strategy

The model proposed in this paper presents a broad range of factors to predict individual human work output. The predictors include aerobic capacity, body size, motivation, work pattern, social environment and social network, caloric intake, drug and alcohol use, stress resistance and thermoregulation. Health is a major intervening variable, and its relationship to work output is a special concern of this research. We suggest that this model may be used as a template to explain human productivity in most societies. Its universality can be subjected to rigorous testing in a range of settings from tropical upland swidden horticulturalists to urban workers in a northern industrialized country. Observations are offered on some of those testing sites and on methodological issues implicit in research of this breadth. A major pilot study of urban Chinese workers has already demonstrated the predictive power of the model in one setting.     

Paleomagnetic evidence of a low-temperature origin of carbonate in the Martian meteorite ALH84001

Indirect evidence for life on Mars has been reported from the study of meteorite ALH84001. The formation temperature of the carbonates is controversial; some estimates suggest 20 degrees to 80 degrees C, whereas others exceed 650 degrees C. Paleomagnetism can be used to distinguish between these possibilities because heating can remagnetize ferrimagnetic minerals. Study of two adjacent pyroxene grains from the crushed zone of ALH84001 shows that each possesses a stable natural remanent magnetization (NRM), implying that Mars had a substantial magnetic field when the grains cooled. However, NRM directions from these particles differ, implying that the meteorite has not been heated significantly since the formation of the internal crushed zone about 4 billion years ago. The carbonate globules postdate this brecciation, and thus formed at low temperatures.     

Tension pneumothorax precluding laparoscopic repair of diaphragmatic hernia

BACKGROUND: Central Europe and the Czech Republic are specific in the prevalence of obesity which has increased by 10-40% during the last 10 years. METHODS: In the Czech republic there is 30 years of experience of a comprehensive approach to obesity treatment which includes: dietary treatment; exercise; behavioral modification; drug treatment; and bariatric surgery. Each of these approaches has its place in complex obesity management. Since 1983 bariatric surgery has been established in the Czech Republic for the treatment of morbid obesity. Vertical banded gastroplasty (VBG), gastric banding, laparoscopic nonadjustable and adjustable gastric bandings have been used over the years. Since 1993 laparoscopic gastric banding has been the only method used in our department. RESULTS: The comprehensive approach for obesity treatment in the Czech Republic has resulted in the development of obesity management and research centers, regional obesity units, obesity out-patients clinics and weight reduction clubs. The surgical treatment is a well-established part of this system and the long-term results of surgical treatment are acceptable both in terms of weight loss and complication rate. There has been no statistical difference in weight loss results following VBG and laparoscopic gastric banding, but there is a significant decrease in morbidity, and shorter hospital stay associated with laparoscopic gastric banding. CONCLUSIONS: The surgical approach in obesity treatment has an important place in the comprehensive care of obese patients. Laparoscopic gastric banding in the hands of an experienced surgeon is a method with low morbidity, short hospital stay and long-term weight loss results which are fully comparable with the results of other surgical approaches.     

Identification of Additional Volatile Compounds from Cbntaloupe

The volatile components of cantaloupe pericarp were analyzed during ripening by gas-liquid chromatography-mass spectrometry. Thirty-two compounds were identified from concentrates prepared by steam distillation-solvent extraction of the volatiles. Eight of the constituents including ethyl (methylthio) acetate, (Z)-6-nonenyl acetate, (Z, Z)-3,6-nonadienyl acetate, benzyl propionate, benzyl alcohol, a sesquiterpene hydrocarbon, cinnamyl acetate and an isomer of 3,4-dimethoxyacetophenone have not been identified previously. Headspace analysis of cantaloupe samples at six stages of maturity showed increases in total ethyl and acetate esters, acetaldehyde, ethyl acetate, and ethanol with maturation. Levels of these compounds remained low and relatively constant until the breaker stage and thereafter increased rapidly until the fruit was fully mature.     

Induction of telomerase activity by UV-irradiation in Chinese hamster cells

Telomerase is a ribonucleoprotein whose activity has been detected in germline cells and in neoplastic and immortal cells. Telomerase compensates the telomere loss arising by the end replication problem by synthesizing telomeric repeats at the 3' end of the eukaryotic chromosomes. Telomerase is reactivated during cancer progression in human and mice. In order to determine whether the telomerase activity can be upregulated in vitro in response to DNA damaging agents, we examined the telomerase activity in five Chinese hamster cell lines following exposure to 5 J/m2 or 40 J/m2 UV-C radiation. All the cell lines tested showed an increase in telomerase activity in the PCR-based telomeric repeat amplification protocol (TRAP) in a dose dependent manner. This increase in telomerase activity correlated well with the number of cells being in the S and G2/M phase after UV exposure. However, in unirradiated control cells, similar levels of telomerase activity were observed in different phases of the cell cycle. Furthermore, telomeric signals were clustered in one or more parts of the disintegrating nuclear particles of the apoptotic cell as detected by fluorescence in situ hybridization (FISH). This is the first study to demonstrate the induction of telomerase activity following exposure to DNA-damaging agents like UV radiation in Chinese hamster cells in vitro.     

Growth hormone secretion and circulating insulin-like growth factor-I (IGF-I) and IGF binding protein-3 concentrations in children with sickle cell disease

Impaired growth involving both height and weight accompanying sickle cell disease (SCD) poses diagnostic and therapeutic problems. We undertook this study to test the hypothesis that this impaired growth is associated with abnormalities of the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF binding protein-3 (IGFBP-3) axis in 21 children with SCD and that SCD is associated with GH resistance. Nine of 21 children with SCD had a defective GH response to both clonidine and glucagon provocation (peak < 10 micrograms/L); these children differed from the 12 others in having slower linear growth velocity (GV and GVSDS), lower circulating concentrations of IGF-I and IGFBP-3, and either partial or complete empty sellae in computed tomographic scans of the hypothalamic-pituitary area. In this group of patients with SCD, it appears that defective GH secretion and consequent low IGF-I production are the major etiological factors causing the slow growth. The two groups with SCD did not differ significantly in dietary intake, body mass index (BMI), midarm circumferences, skinfold thickness, serum albumin concentration, or intestinal absorption of D-xylose. A single injection of GH produced a smaller increase in circulating IGF-I in children with SCD with or without defective GH secretion versus 10 age-matched children with idiopathic short stature (ISS) and 11 children with isolated GH deficiency (GHD), suggesting partial GH resistance in the SCD group. The presence of defective GH secretion, decreased IGF-I synthesis, and partial resistance to GH in short children with SCD suggests that treatment with IGF-I may be superior to GH therapy for improving growth.     

Determination of plasma concentrations of propofol associated with 50% reduction in postoperative nausea

BACKGROUND: Subhypnotic doses of propofol possess direct antiemetic properties. The authors sought to determine the plasma concentration of propofol needed to effectively manage postoperative nausea and vomiting. METHODS: Patients aged 18-70 yr who were classified as American Society of Anesthesiologists physical status 1 or 2 and had surgery during general anesthesia were approached for the study. Only patients who had nausea (verbal rating score > 5 on a 0- to 10-point scale), retching, or vomiting in the postanesthetic care unit participated. Propofol was administered to these patients to achieve target plasma concentrations of 100, 200, 400, and 800 ng/ml using a computer-assisted continuous infusion device. Target concentrations were increased every 15 min until patients described at least a 50% reduction in symptoms on the verbal rating score. An arterial blood sample was obtained at each step. The measured plasma propofol concentrations were used to analyze data. Blood pressure, heart and respiratory rates, arterial blood saturation, sedation score, and overall satisfaction with treatment were recorded. RESULTS: Of the 89 patients who consented to the study, 15 patients met entry criteria and were enrolled. Five of these patients also had retching or vomiting when they entered the study. Fourteen patients responded successfully to treatment. One patient did not achieve the required response at plasma concentrations of 830 ng/ml. Hence the success rate for the treatment of postoperative nausea and vomiting was 93%. Among patients who responded, the median plasma concentration associated with an antiemetic response was 343 ng/ml. There was no difference in sedation scores from baseline and no episodes of desaturation. Hemodynamic parameters were stable during the study. CONCLUSIONS: Propofol is generally efficacious in treating postoperative nausea and vomiting at plasma concentrations that do not produce increased sedation. Simulations indicate that to achieve antiemetic plasma propofol concentrations of 343 ng/ml, a bolus dose of 10 mg followed by an infusion of approximately 10 microg x kg(-1) x min(-1) are necessary.