Conformation and gas permeability of poly(α-amino acid) membranes

The permeability of some poly(?-amino acid) (PAA) membranes like such of poly(N,δ-carbobenzoxy-L -lysine) (PCBL), poly(N,δ-carbobenzoxy-L -ornithine) (PCBO) as well as of copolymers of L -lysine and carbobenzoxy-L -lysine to oxygen and carbon dioxide were determined at different water content especially with regard to their use for artificial lungs. The conformations of these polymer membranes were studied by means of IR-spectra and X-ray diffraction. The results on the diffusion coefficient obtained for PCBL and PCBO were analysed in terms of Eyring's theory. They suggest that the microvoids in the interstices between the α-helices, assumed on the basis of X-ray analyses, play an important role, especially below the glass transition temperature T_g of the side-chains. This seems also to contribute partly to the diffusion of gas through the membrane even above T_g and results in an abnormally high “apparent activation energy” of diffusion in the wet state below T_g. It was found that the permeability of the membrane of partially decarbobenzoxylated PCBL for oxygen in a certain temperature range is higher than that for carbon dioxide. This has never been observed for any other synthetic polymer, because usually carbon dioxide has a higher solubility in these materials than oxygen. In the case of the partially decarbobenzoxylated PCBL membranes, however, the diffusion coefficient of carbon dioxide, and therefore the permeation of this gas, decreases much more than that of oxygen with increasing decarbobenzoxylation accompanied by the formation of β-structure and concomitantly the formation of intermolecular hydrogen bonds. Obviously, this phenomenon may be responsible for the permselectivity of these membranes for oxygen compared with carbon dioxide.     

Effects of low-level microwave irradiation on amphetamine hyperthermia are blockable by naloxone and classically conditionable

In a series of experiments, we investigated the effects of pulsed low-level microwave irradiation on amphetamine-induced hyperthermia in the rat. Rats were irradiated in a 2,450-MHz cylindrical waveguide exposure system at 1 mW/cm², 2 s pulses, 500 pps, average SAR of 0.6 W/kg. Acute (45 min) exposure to microwaves attenuated amphetamine-induced hyperthermia. This effect was blocked by pretreatment of the animals with the narcotic antagonist naloxone. In another experiment, rats were subjected to ten daily sessions of microwave exposure (45 min/session). On day 11, amphetamine-induced hyperthermia was studied in the animals immediately after a session of either microwave or sham exposure. Similar to the acute effect, amphetamine-induced hyperthermia was attenuated in rats irradiated with microwaves (unconditioned effect). In the sham-irradiated animals we observed a potentiation of the amphetamine-induced hyperthermia, which was a conditioned effect of microwaves. Thus, the conditioned effect (potentiation) was opposite in direction to the unconditioned effect (attenuation). No tolerance developed to the unconditioned effect after subchronic exposure. Furthermore, both conditioned and unconditioned effects of microwaves on amphetamine-induced hyperthermia could be blocked by treatment with naloxone. These data suggest that (1) microwave irradiation may activate endogenous opioids, which in turn alter the actions of psychoactive drugs, and (2) the effect of microwaves on drug action can be classically conditioned. Offprint requests to: H. Lai     

Familial Transmission of Alcohol Use Norms and Expectancies and Reported Alcohol Use

Members of 183 families (biological parents and one adult offspring) completed questionnaires on their quantity and frequency of alcohol use, what they would consider a "normal" quantity-frequency of alcohol use, "problem" quantity-frequency of use, flushing after alcohol use, and other expected physiological and subjective responses to alcohol. Within individuals, own quantity-frequency of alcohol use was moderately negatively correlated with flushing after one drink or less ("fast flushing"), but more highly positively correlated with judged normal alcohol use and with expected subjective effects. Spouse resemblances were low for quantity-frequency of alcohol use and flushing, but high for alcohol use norms and expected physiological and subjective responses. Parent-offspring resemblances were low to moderate for own alcohol use and flushing, but moderate to high for expected physiological and subjective effects. These results were discussed in terms of the effects of genetically transmitted flushing after alcohol use and culturally transmitted alcohol norms and expectations on alcohol use.     

Site of bone density measurement may affect therapy decision

Summary The purpose of this study was to determine whether bone mineral density (BMD) measurements at the lumbar spine and femoral neck provided comparable information to women planning to use that knowledge to help them make a decision about hormone replacement therapy. Eighty-eight healthy Caucasian women, aged 44–59 and within 0 to 5 years of menopause, participated in the study. BMD measurements were performed at the lumbar spine (L1-L4) and the femoral neck by dual energy X-ray absorptiometry (DXA). Criteria suggested by the National Osteoporosis Foundation were used to categorize women as at risk for osteoporosis, bone density more than one standard deviation (SD) below the young adult mean, or as low risk, bone density at or above this level. The re that 46 women would be classified into the low risk category on the basis of spinal BMD alone. However, 28 of these 46 women would fall into the at risk category when the femoral neck BMD was measured. Sixty-one percent of women informed they were at low risk on the basis of spinal BMD would be considered at risk based on femoral neck BMD. When femoral neck BMD was used as the primary risk indicator, 14% of the women classified as low risk would be at risk if spinal BMD were added. These results suggest that both lumbar spine and proximal femur measurements should be made when women are using bone density measurements as an aid in deciding whether or not to use hormone therapy in their postmenopausal years.     

Ocular findings in beta-thalassemia

Eye examination was performed in a series of 53 patients whose mean age was 19.5 years (range from 11 to 25 years), affected from Cooley's disease, in treatment with transfusions and desferrioxamine in subcutaneous infusion. The most frequent ocular change was fundus mottling appearance like "leopard skin" (15%). We found also lens opacity (11%), drusen (7%), retinal venous tortuosity (5%), without impairment of visual acuity. The pathogenic factors of the ocular change are related to abnormality of iron metabolism. These results suggest that the involvement of desferrioxamine to remove iron from the eyeball is relatively small.     

Comparison of topoisomerase I and II expression in primary brain tumor and lung cancer

Topoisomerase I (TOP I) and II (TOP II) activities and their corresponding levels were analyzed in 27 primary brain tumors and 32 lung cancers (28 NSCLC, 4 SCLC). The TOP I and II activities in primary brain tumors varied from 500-2,000 units/mg and 100-3,000 units/mg respectively. Their corresponding levels varied from <0.01-3.30 (TOP I) and 0.24-8.30 (TOP II) arbitrary units. In lung cancer, the TOP I and II activities ranged from 1,000-4,000 and 500-4,000 units/mg respectively with their levels ranging from 0.30-61.60 and 0.2-14.2 arbitrary units respectively. These parameters were compared in both tumors using the Wilcoxon rank sums test, the difference were statically significance for all four parameters with a p<0.0001 for TOP I and II activities and TOP I levels and p<0.09 for TOP II levels. Using linear regression analysis, there was no correlation between TOP I and II activities and their corresponding levels in primary brain tumor. However, in lung cancer, the relationship between TOP I activities and levels were linear with r(2)=0.2 and p<0.0094, but not for TOP II activity and their levels. There was no relationship between TOP I and TOP II levels in the same tumor for both types of cancer. The future clinical implication of these findings are discussed.     

Complete nucleotide sequence of mouse mammary tumor virus from jyg chinese wild mice: Absence of bacterial insertion sequences in the cloned viral gag gene

Mammary tumors of a newly isolated strain of Chinese wild mouse (JYG mouse) harbor exogenous mouse mammary tumor virus (MMTV). The complete nucleotide sequence of exogenous JYG-MMTV was determined on the proviral 5' long terminal repeat (LTR)(partial)-gag-pol-env-3' LTR (partial) fragment cloned into a plasmid vector and the cDNA sequence from JYG-MMTV producing cells. Similarly to the other MMTV species the LTR of JYG-MMTV contains an open reading frame (ORF). The amino acid sequence of the JYG-MMTV ORF resembles that of SW-MMTV (92% identity) and endogenous Mtv-7 (93% identity) especially at the C-terminal region. Thus, a functional similarity in T-cell receptor V beta recognition as a superantigen is implicated among these MMTV species. Analysis of the viral gag nucleotide sequence revealed that this gene is not disrupted by the bacterial insertion sequence IS1 or IS2, which have been reported to be present in the majority of the plasmids containing the gag region. Comparison of amino acid sequences of JYG-MMTV with those of BR6-MMTV showed that over 96% of the amino acids of gag, pol, protease and env products are identical. These results suggest the intact nature of the nucleotide sequence of the near full-length MMTV genome cloned in the plasmid.     

Comparison of growth status of patients with cystic fibrosis between the United States and Canada

BACKGROUND: Differences in growth status of patients with cystic fibrosis (CF) between the United States and Canada were reported in the 1980s based on analysis of data from 2 regional CF centers. OBJECTIVE: We evaluated the current growth status of the entire CF population in the United States and Canada in view of recent advances in the treatment of CF. DESIGN: Growth data from the 1992-1994 CF Patient Registries were analyzed. RESULTS: Mean height and weight were at approximately the 30th percentile for children with CF in the United States. Mean height and weight were 4-5 percentiles higher in children with CF in Canada than in those in the United States (P < 0.01), but percentages of ideal weight (104%) were similar in both populations. In adults with CF, mean height was similar at the 37th percentile; however, weight (26th compared with the 21st percentiles) and percentage of ideal weight (93% compared with 90%) were significantly higher in Canada than in the United States. Differences related to sex and age were similar in both countries for all indexes, which showed a high prevalence of underweight in infants and in older patients, but little sex discrepancy. CONCLUSION: We observed substantially smaller differences in the growth indexes of CF patients between the United States and Canada compared with results from the 1980s. These findings reflect significant improvements in the nutritional status of US patients in recent years. However, caution is required in the direct comparison of mean percentiles from reports using different growth standards because there are systematic differences in growth standards, which affect, in particular, the comparison of growth in males and females.     

Rectal cancer mortality and total hardness levels in Taiwan's drinking water.

The possible association between the risk of rectal cancer and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with deaths from other causes (986 controls), and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan were collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and the controls were pair matched to the cases by sex, year of birth, and year of death. The results show a significant negative relationship between drinking water hardness and rectal cancer mortality. Odds ratio and 95% confidence intervals were 1.24 (1.01-1. 55) and 1.38 (1.10-1.73), respectively, for exposure to moderately hard water and soft water compared with the use of hard water. Trend analyses showed an increasing odds ratio for rectal cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health.