An extension to the known range of the desert mouse Pseudomys desertor south into the Great Victoria Desert, Western Australia

THE desert mouse Pseudomys desertor is a medium sized rodent (15 – 30 g) which has a widespread distribution throughout the arid zone of Australia (Menkhorst and Knight 2001). It is considered locally abundant in habitats containing samphire, sedge, nitrebush or mature spinifex grasslands. A tolerance to disturbed habitat (from mining or grazing) has also been noted (Read et al. 1999). The distribution of the species once extended from the Murray-Darling through the Flinders Ranges to the Gibson and Great Sandy Deserts, to the west coast and onto Bernier Island (Read et al. 1999; Menkhorst and Knight 2001). Since European colonisation there has been a contraction of the species’ range to the central deserts (Kerle 1995; Read et al. 1999). In Western Australia, the most southerly historical or contemporary record, is from the Wanjarri Nature Reserve (near Mount Keith), 370 km north of Kalgoorlie (D. Pearson pers. comm.; Western Australian Museum fauna database: http://203.30.234.168/). Recently, however, a suspected P. desertor was caught north-west of Queen Victoria Springs (QVS) in the Great Victoria Desert (GPS 30o 03’ 56’’S; 122o 55’ 28’’E), approximately 350 km to the south-east of its most southern known locality. The specimen had the distinctive buff-orange eye ring, size and general features of P. desertor described in Kerle (1995) and Menkhorst and Knight (2001). Prior to release of the specimen, an ear biopsy was obtained for DNA investigation and genomic DNA was extracted from the biopsy via a variation on the salting out procedure of Miller et al. (1988).

Respiratory symptoms, bronchitis and asthma in children of Central and Eastern Europe

The multicentre Central European Study of Air Pollution and Respiratory Health (CESAR) aimed to measure the respiratory health of schoolchildren using a standardised questionnaire in six countries of Central and Eastern Europe (CEE), allowing comparisons within this region and with other European countries. A cross-sectional study was conducted in 25 urban areas of Bulgaria, Czech Republic, Hungary, Poland, Romania, and Slovakia in 1996. Parents of 21,743 schoolchildren of age 7-11 yrs completed a questionnaire based on items from the World Health Organization and International Study of Asthma and Allergies in Childhood questions on cough and wheeze symptoms, as well as on diagnoses by doctors. Life-time prevalence of bronchitis was 55.9%, asthma 3.9%, and asthmatic, spastic or obstructive bronchitis 12.3%. In CEE countries the prevalence of bronchitis is higher and prevalence of asthma appears lower than in Western Europe. However, if asthma is defined as a diagnosis of either asthma or asthmatic, spastic or obstructive bronchitis, then its prevalence is comparable to Western Europe, or higher. In this region, within-country variation for most respiratory parameters is less than between-country variation. Between-country comparisons in doctors' diagnoses appear dependent on the choice of definition of asthma. Europe-wide comparisons in prevalence of respiratory symptoms and diagnosis are reported in this study. Some of the East-West difference in asthma prevalence may be attributable to differences in diagnostic practice.

Personality testing and profiling for anaesthetic job recruitment: attitudes of anaesthetic specialists/consultants in New Zealand and Scotland

Specialist/consultant anaesthetists based in New Zealand and Scotland were sent a reply paid postal questionnaire asking about their attitudes to personality testing and personality types in the recruitment process for registrars and specialists. The questionnaire consisted of nine Likert-style questions and 14 visual analogue questions. The overall response rate was 65% (523/808). The responses to all the questions were broadly similar in the two countries. Personality testing was deemed of use in recruiting trainees and specialists, with a slightly greater proportion considering personality traits more important than academic achievement. An overwhelming majority believed the presence of an adverse personality trait would influence an appointment process, but few believed that the personality makeup of anaesthetists influenced the way in which they react to stressful situations. A slight majority considered the interview process a poor predictor of personality. New Zealand anaesthetists rated independence, orderliness, compassion, empathy, reflectiveness and patience higher than did anaesthetists in Scotland. In contrast, anaesthetists in Scotland rated pragmatism, as opposed to perfection, as a more important characteristic than did the New Zealand specialists. Personality assessment, although not effective as the sole tool for candidate selection, may have a role in the process of anaesthetic job recruitment and warrants further investigation.

Time series analysis of air pollution and mortality: effects by cause, age and socioeconomic status

OBJECTIVE

To investigate the association between outdoor air pollution and mortality in São Paulo, Brazil.

DESIGN

Time series study

METHODS

All causes, respiratory and cardiovascular mortality were analysed and the role of age and socioeconomic status in modifying associations between mortality and air pollution were investigated. Models used Poisson regression and included terms for temporal patterns, meteorology, and autocorrelation.

MAIN RESULTS

All causes all ages mortality showed much smaller associations with air pollution than mortality for specific causes and age groups. In the elderly, a 3-4% increase in daily deaths for all causes and for cardiovascular diseases was associated with an increase in fine particulate matter and in sulphur dioxide from the 10th to the 90th percentile. For respiratory deaths the increase in mortality was higher (6%). Cardiovascular deaths were additionally associated with levels of carbon monoxide (4% increase in daily deaths). The associations between air pollutants and mortality in children under 5 years of age were not statistically significant. There was a significant trend of increasing risk of death according to age with effects most evident for subjects over 65 years old. The effect of air pollution was also larger in areas of higher socioeconomic level.

CONCLUSIONS

These results show further evidence of an association between air pollution and mortality but of smaller magnitude than found in other similar studies. In addition, it seems that older age groups are at a higher risk of mortality associated with air pollution. Such complexity should be taken into account in health risk assessment based on time series studies.

Methodological approaches to the analysis of hierarchical studies of air pollution and respiratory health--examples from the CESAR study. Central European Study on Air pollution and Respiratory Health

OBJECTIVES

Many studies of air pollution and health are carried out over several geographical areas, and sometimes over several countries. This paper explores three approaches to analysis in such studies: a non hierarchical model, a two-stage analysis, and multilevel modelling. Illustrations are given using a preliminary subset of data from the CESAR study.

DESIGN

The Central European Study on Air pollution and Respiratory Health (CESAR) was conducted in 25 areas within six Central European countries, enrolling 20,271 schoolchildren. Pollution averages were calculated for each area. Associations between pollution and health outcomes were estimated under different models.

MAIN RESULTS

A regression analysis of log FVC (forced vital capacity) on PM10, ignoring the geographical hierarchy, estimated a significant mean drop in FVC (adjusted for confounders) of 2.2% (95% CI 0.5% to 1.3%), p=0.007, from the area with the lowest PM10 to that with the highest. A multilevel model (mlm), using data for all children, but with random effects at area and country level, estimated a drop of 2.8% (-0.6% to 6.1%), p=0.110. A two-stage analysis (mean log FVC, adjusted for confounders, was estimated for each area using regression, and these means then regressed on PM10) estimated a drop of 2.6% (-0.5% to 5.5%), p=0.101. Simulation exercises showed the non hierarchical method to be very inadequate in the context of the CESAR study, with only half of all 95% confidence intervals for the estimated PM10 slope containing the true value (i.e., that used to create the simulated data). The two-stage and multilevel modelling methods gave results which were substantially better, though both underperformed slightly. All three methods appeared to give unbiased slope estimates.

CONCLUSIONS

Acknowledgement of hierarchical structures is essential in statistical inference--standard errors can be substantially incorrect when they are ignored. Multilevel, random-effects models correctly address hierarchical structures, though having few units at higher levels can cause problems in convergence, especially where complex modelling is required. Two-stage analyses, acknowledging hierarchy, provide simple alternatives to random-effects models.

Respiratory diseases in children and outdoor air pollution in São Paulo, Brazil: a time series analysis

OBJECTIVES

To investigate the short term effects of air pollution on the respiratory morbidity of children living in São Paulo, Brazil, one of the largest cities in the developing world.

METHODS

Daily counts of hospital admissions due to respiratory diseases along with daily levels of meteorological variables and air pollutants (PM(10), SO(2), NO(2), O(3), and CO) were analysed with Poisson regression. Final models were adjusted for the effects of time trends, seasonal patterns, weekdays, holidays, meteorological factors, and serial correlation.

RESULTS

Daily admissions of children to hospital for total respiratory disease and pneumonia showed significant increases associated with O(3) (5-8%), NO(2) (9%), and with PM(10) (9%) (results are for an increase from the 10th to the 90th percentile of pollution measurements). Consistently, effects for pneumonia were greater than for all respiratory diseases combined. Also, effects on infants (children <1 year old) presented higher estimates. Similar associations were found for asthma admissions. Point estimates for most pollutants were higher for asthma than for other diagnosed admissions. However, these associations were not significant.

CONCLUSIONS

These results agree with the limited publications on this subject but indicate a rather smaller magnitude of effects. Nevertheless, given the present concentrations of air pollution in São Paulo and the large population potentially exposed attention should be directed to minimise such effects.

Parental agricultural work and selected congenital malformations

The authors conducted a case-control study in Comunidad Valenciana, Spain, to assess the relation between occupational exposure to pesticides, mainly as a result of agricultural work, and the prevalence of congenital malformations. A total of 261 cases and 261 controls were selected from those infants born in eight public hospitals during 1993-1994. The cases were those who were diagnosed with selected defects (nervous system, cardiovascular, oral clefts, hypospadias/epispadias, musculoskeletal, and unspecified anomalies) during their first year of life. Information on occupational exposures and potential confounding variables was collected from the parents. For the mothers who were involved in agricultural activities during the month before conception and the first trimester of pregnancy, the adjusted odds ratio was 3.16 (95% confidence interval 1.11-9.01) primarily due to an increased risk for nervous system defects, oral clefts, and multiple anomalies. Paternal agricultural work did not increase the risk, although fathers who reported ever handling pesticides had an adjusted odds ratio of 1.49 (95% confidence interval 0.94-2.35) mainly related to an increased risk for nervous system and musculoskeletal defects. Although the power of this study regarding some associations is limited, the results justify further attention to maternal agricultural work and paternal pesticide exposure.

Paternal exposure to pesticides and congenital malformations

OBJECTIVES

A case-referent study with 261 matched pairs was carried out in 8 hospitals of Comunidad Valenciana, Spain, to assess the relation between occupational exposure to pesticides and selected congenital malformations. In this paper, the results concerning paternal exposure are presented.

METHODS

The parents of the case patients and the referents were interviewed to collect information about exposure to pesticides and potential confounding variables. Detailed information on direct involvement in the handling of pesticides was collected for the interviewees involved in agricultural activities during a previously defined period in relation to conception and pregnancy. Exposure data were reviewed by 2 experts who assigned ordinal scores for the probability and intensity of exposure to pesticide classes and active ingredients.

RESULTS

The dichotomous analysis of exposure (absent, present) yielded some increased risks, although not statistically significant, for aliphatic hydrocarbons [adjusted odds ratio (adjusted OR) 2.05, 95% confidence interval (95% CI) 0.62-6.80], inorganic compounds (adjusted OR 2.02, 95% CI 0.53-7.72), and glufosinate (adjusted OR 2.45, 95% CI 0.78-7.70), and a significant association for pyridil derivatives (adjusted OR 2.77, 95% CI 1.19-6.44). The analysis based on the experts' scores (2 levels of exposure) showed some consistent associations for these compounds.

CONCLUSIONS

This research indicates a possible risk of congenital malformations for paternal exposure to some pesticides, notably, pyridils, aliphatic hydrocarbons, inorganic compounds, and glufosinate. It did not find an increased risk for paternal exposure to pesticides in the classes of organophosphates, carbamates, organochlorines, chloroalkylthio fungicides and organosulfurs. These findings warrant further investigation.

CVT-124, a novel adenosine A1 receptor antagonist with unique diuretic activity

Administration of the selective adenosine A1 receptor antagonist, CVT-124, to conscious chronically instrumented rats resulted in significant increases in urine flow rate and sodium excretion without affecting potassium excretion or renal hemodynamics. Its maximum effect was twice that of hydrochlorothiazide which was associated with a significant kaliuresis. The diuretic effect of CVT-124 was less than that observed with furosemide; however, furosemide administration was associated with a large increase in potassium excretion as well as a reduction in glomerular filtration rate. When given at equinatriuretic doses, CVT-124 enhanced the diuretic and natriuretic activity of furosemide without further increasing potassium excretion. In contrast, the combination of hydrochlorothiazide and furosemide resulted in a 3-fold increase in potassium excretion. These data suggest that CVT-124 possesses unique diuretic activity and, as such, it represents a potential new therapeutic in fluid retaining disorders. In addition, its unique mechanism of action suggests that CVT-124 would be effective in otherwise diuretic-resistant patients.

Maternal occupation in the leather industry and selected congenital malformations

OBJECTIVES

Data from a hospital based case-control study were analysed to assess the relation between maternal occupation in the leather industry and several groups of congenital defects (nervous system, cardiac defects of closure, oral cleft, epispadia or hypospadia, and multiple anomalies).

METHODS

Cases and controls were selected from eight public hospitals in Comunidad Valenciana, Spain, in 1993 and 1994. Cases were located from the hospital discharge records, including children born and diagnosed in some of the selected hospitals during their first year of life. Controls were selected from births without congenital defects in the same hospitals and dates of the cases (ratio 1:1). Both parents of selected children were interviewed (mainly by phone) and information about potential confounding variables and occupational history during the three years before the birth was collected in structured questionnaires.

RESULTS

A total of 261 cases and the same number of controls were included in the study. Adjusted odds ratios (ORs) were estimated for maternal occupation in the leather industry in the period between three months before the conception and the birth of the child (n = 22), and each selected group of congenital malformations: nervous system defects (OR 1.02, 95% confidence interval (95% CI) 0.12 to 8.51), cardiac defects of closure (OR 1.78, 95% CI 0.44 to 7.17), oral clefts (OR 6.18, 95% CI 1.48 to 25.69), for epispadia or hypospadia (OR 4.05, 95% CI 0.77 to 21.44), and multiple anomalies (OR 3.14, 95% CI 0.82 to 12.00).

CONCLUSION

These data are compatible with an increased risk for oral clefts in the offspring of women working in the leather industry. Some other categories of defect could have an increased risk as well, although for these our data cannot exclude random error as an explanation. Given these results and previous findings in similar studies, some precautionary recommendations regarding maternal exposure in leather industries, probably in relation to solvents, would be justified.

Contribution of endogenous endothelin-1 to the maintenance of vascular tone: role of nitric oxide

Studies were designed to compare the effect of the nitric oxide inhibitor, N omega-nitro-L-arginine (L-NNA), and the novel ETB receptor antagonist, RES-701-1, on changes in blood pressure and renal blood flow induced by exogenous endothelin receptor agonists and to determine the effect of L-NNA on basal hemodynamics in conscious, chronically instrumented rats. Infusion of low (nonpressor) doses of L-NNA or RES-701-1 potentiated systemic and renal vasoconstriction induced by bolus injections of endothelin-1 or sarafotoxin 6c. Bolus intravenous injection or sustained infusion of L-NNA alone resulted in dose-dependent increases in blood pressure and decreases in renal blood flow, similar to our recently reported results with RES-701-1. Vasoconstriction induced by inhibition of nitric oxide was attenuated by SB 209670, a mixed ETA/B receptor antagonist, but not by BQ123, an ETA receptor antagonist; neither antagonist altered basal hemodynamics. Collectively, the results indicate that: (1) endothelin plays an important role in the control of basal vascular tone by mediating both vasodilation and vasoconstriction; (2) these effects are mediated by different ETB receptor subtypes in the rat, one located on the endothelium that mediates vasodilation via the nitric oxide pathway, the other located on the vascular smooth muscle that mediates contraction.

[Validation of a questionnaire for retrospectively measuring occupational pesticide exposure]

OBJECTIVE

The aim of this study is to validate a questionnaire intended to assess retrospective occupational exposure to pesticides in a case control study of workers exposed to pesticides and congenital malformations.

METHODS

Occupational data were gathered through personal interviews to 56 agricultural workers and this information was compared to: 1) personal interviews with the workers' foremen, 2) direct observation of working places and 3) another questionnaire self-administered previously by the workers as a part of the "Training Program for Pesticide Applicators".

RESULTS

Accuracy and reliability indices are high for variables such as the crops where the interviewees have been working, the time period of the treatments with pesticides and the use of personal protection during treatments (sensitivity ranges between 0.81 and 1 and Kappa index ranges between 0.65 and 0.80). However, for variables such as the duration of the treatments and the pesticides used, sensitivity values range between 0.32 and 0.50.

CONCLUSIONS

The results suggest that the questionnaire is a valid tool for measuring some items but in order to improve the quality of the exposure assessment the questionnaire was modified, including a question about size of treated areas (as a proxy variable for duration of treatments) and prompt lists were developed to make easier recall by the workers of specific pesticides used in treatments.

Patients' satisfaction when denied authorization for emergency department care by their managed care plan

We conducted a survey of managed care plan (MCP) patients who presented to the emergency department (ED) but were denied insurance authorization during a 3-month period. Patients were identified by triage or registration records, contacted by telephone after their visit, and surveyed regarding their satisfaction with the ED and MCP, follow-up care, and future behavior. We surveyed 72 (73.4%) of 98 subjects who were denied authorization. Forty-nine (68.1%) were redirected to a clinic or primary physician, 14 (19.4%) to an urgent care or other ED, and 9 (12.5%) were given no follow-up. Fifty-five respondents (76.4%) stated they had followed-up as directed, but 34 (47.2%) felt the delay had a negative impact. Thirty-nine (54.2%) were dissatisfied with their MCP. If their problems were to recur, 27 (37.5%) stated they would go to a clinic or call their MCP, but 34 (47.2%) would return to the ED. Many patients who are denied authorization are dissatisfied with their MCP and will return to the ED in the future, despite previous denials.

Evidence for the existence of endothelin-B receptor subtypes and their physiological roles in the rat

The physiological roles of endothelin-B (ETB) receptor subtypes in systemic and renal hemodynamics were assessed in conscious Sprague-Dawley rats. Mean arterial pressure, hindlimb flow, and renal blood flow were measured via an implanted catheter and pulsed Doppler flow probes. Bolus intravenous injections of sarafotoxin 6c (S6c), a selective ETB agonist, elicited transient dose-dependent vasodilation, followed by sustained vasoconstriction in the systemic bed, but only vasoconstriction in the renal bed. RES-701-1, a selective ETB antagonist, blocked the dilator and potentiated the constrictor effect; SB-209670, a mixed ET receptor antagonist, attenuated both responses to S6c. In follow-up studies, the role of endogenous ET was assessed by administration of the antagonists alone: RES-701-1, SB-209670, and the ETA-selective antagonist BQ-123. RES-701-1 unmasked a significant systemic and renal vasoconstriction, which was attenuated by SB-209670 but not by BQ-123. SB-209670 and BQ-123 had no effect on basal hemodynamic parameters. Data from radioligand binding experiments showed that RES-701-1 binds with high affinity to the cloned human ETB receptor but poorly to the ETB receptor predominant in the rat kidney. Collectively, the results indicate that 1) the vascular effects of ET in the rat are mediated by two ETB receptor subtypes: an RES-701-1-sensitive subtype, mediating vasodilation, and an RES-701-1-insensitive subtype, mediating vasoconstriction; 2) the predominant role of endogenous ET is vasodilation; and 3) the ETA receptor plays a negligible role in the control of vascular tone in the rat.

Nonpeptide endothelin receptor antagonists. V: Prevention and reversal of acute renal failure in the rat by SB 209670

The ability of the mixed endothelin (ETA/ETB) receptor antagonist (+/-)-SB 209670 to prevent and reverse ischemia-induced acute renal failure (ARF) was studied in rats with moderate and severe ARF. Uninephrectomized, chronically instrumented Sprague-Dawley rats were used. Moderate and severe ARF was induced by occlusion of the renal artery for 30 and 45 min, respectively. During the 24 hr after 30-min ischemia (moderate ARF), glomerular filtration rate (GFR) decreased by 95%, and fractional excretion of sodium increased from 0.6% to 10%. Infusion of (+/-)-SB 209670 at 10, 30 and 100 micrograms/kg.min for 30 min before, during and 60 min after renal ischemia had a moderate effect on renal function. Thus, with the highest dose, the ischemia-induced reduction in GFR was 70%. This dose, however, had no effect in rats when given before, during and after 45 min of renal ischemia (severe ARF). In contrast, when infused at 30 micrograms/kg.min for 3 hr on the day after ischemia, (+/-)-SB 209670 markedly increased survival rate (75%) in rats with severe ARF by significantly increasing tubular reabsorption of Na+, followed by a slow and gradual increase in GFR and reversal of the increase in plasma K+ concentration. Data from acute renal clearance studies in rats with moderate ARF showed that when infused 24 hr after ischemia, (+/-)-SB 209670 acutely reversed the impairment in sodium reabsorption without increasing GFR or renal blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Autosomal dominant zonular cataract with sutural opacities localized to chromosome 17q11-12

Congenital cataracts constitute a morphologically and genetically heterogeneous group of diseases that are a major cause of childhood blindness. Different loci for hereditary congenital cataracts have been mapped to chromosomes 1, 2, 16, and 17q24. We report linkage of a gene causing a unique form of autosomal dominant zonular cataracts with Y-sutural opacities to chromosome 17q11-12 in a three-generation family exhibiting a maximum lod score of 3.9 at D17S805. Multipoint analysis gave a 1-lod confidence interval of 17 cM. This interval is bounded by the markers D17S799 and D17S798, a region that would encompass a number of candidate genes including that coding for beta A3/A1-crystallin.

Mortality study of construction workers in the UK

BACKGROUND

Construction is one of the most dangerous industries in the world. However, there has been little literature on occupational epidemiology in this field. A study of the mortality experience over a 13-year period among construction workers in the UK was carried out.

METHOD

This was based on 15,007 death certificates of members of the Building and Civil Engineering Holiday and Benefit Scheme, who had died during 1975 to 1987 aged 20-64 years. Proportional mortality ratio (PMR) and mortality odds ratio techniques were used.

RESULTS

Significantly elevated PMR were found for deaths from all cancers, including cancer of the lung and stomach, and for accidental deaths. Associations were demonstrated between several job categories and an increased risk of cancer mortality. Occupational exposures to hazardous substances may have contributed to the elevated cancer mortality, although the study findings should be interpreted with caution. Inadequate supervision of safety procedures, together with a high proportion of young and inexperienced workers, may be associated with the high number of accidental deaths.

CONCLUSIONS

The results support the hypothesis that working in the construction industry is associated with a high risk for accidental death and probably also for malignant diseases including lung, mesothelium and stomach cancers. Further epidemiological studies among construction workers are needed to support policies aimed at improving occupational health, including the prevention of accidents.

Reversal of postischemic acute renal failure with a selective endothelinA receptor antagonist in the rat

Studies were designed to examine the effect of a selective endothelinA (ETA) receptor antagonist, BQ123, on severe postischemic acute renal failure (ARF) in Sprague-Dawley rats. Severe ARF was induced in uninephectomized, chronically instrumented rats by 45-min renal artery occlusion. BQ123 (0.1 mg/kg.min) or vehicle was infused intravenously for 3 h on the day after ischemia. Measurements before infusion (24 h control) showed a 98% decrease in glomerular filtration rate (GFR), increase in fractional excretion of sodium from 0.6 to 39%, and in plasma K+ from 4.3 to 6.5 mEq/liter. All vehicle-treated rats died in 4 d because of continuous deterioration of renal function, resulting in an increase of plasma K+ to fatal levels (> 8 mEq/liter). Infusion of BQ123 significantly improved survival rate (75%) by markedly improving tubular reabsorption of Na+ and moderately increasing GFR and K+ excretion. Plasma K+ returned to basal levels by the 5th d after ischemia. Improved tubular function was followed by gradual recovery in GFR and urinary concentrating mechanism. Additional data from renal clearance studies in rats with moderate ARF (30-min ischemia) and in normal rats with intact kidneys showed that ETA receptor blockade increases Na+ reabsorption and has no effect on renal hemodynamics. These results indicate that in the rat, the ETA receptor subtype mediates tubular epithelial function, and it plays a significant role in the pathogenesis of ischemia-induced ARF. Treatment with the selective ETA receptor antagonist reverses deteriorating tubular function in established ARF, an effect of possible therapeutic significance.

Investigation of parameters influencing intraocular pressure increases during sleep

In previous studies, we have observed that young normal subjects show an increase in intraocular pressure (IOP) after sleep. Here we describe three experiments which investigated: (i) the effects of sleep in five groups of subjects: glaucoma, suspect glaucoma, young high-normal IOP, old high-normal IOP groups and an elderly control group, (ii) the effect of exposure to bright light (2500 lux) during sleep on associated IOP changes, and (iii) the relationship between changes in IOP and plasma melatonin during sleep. For all experiments IOP was measured before and after sleep. We found that IOP increased significantly after sleep. There was also a significant difference between the five groups with the old high-normal group showing the greatest increase, and the young high-normal group showing the lowest increase in IOP. The increase in IOP after sleep was reduced when the same subjects slept in bright light compared to that recorded when subjects slept in the dark. Plasma melatonin levels, as well as IOP, increased after sleep in the dark although there was no correlation between these changes for individual subjects.

Kinetic parameters of 5 alpha-reductase activity in stroma and epithelium of normal, hyperplastic, and carcinomatous human prostates

To study the influence of 5 alpha-reductase on the concentration of dihydrotestosterone in prostatic tissue, we measured the activity of this enzyme in stroma and epithelium from 15 normal, 50 hyperplastic, and 20 carcinomatous prostates. Maximum velocity (Vmax) and Km parameters based on the Lineweaver-Burk and Eadie-Hofstee transformations of the Michaelis-Menten equation were related to the stromal and epithelial concentrations of dihydrotestosterone. On the basis of relative Vmax values, there was 6-15 times more 5 alpha-reductase activity in stroma than in epithelium regardless of the histology of the prostate. Stromal enzyme activity also was unique in having a 2- to 5-fold larger mean Km value and greater resistance to competitive and noncompetitive inhibition. Despite the enrichment of 5 alpha-reductase activity in stroma, the dihydrotestosterone concentrations in the stromal and epithelial fractions were very similar. In addition, similar concentrations were found in the stromal fractions of hyperplastic and carcinomatous tissues, notwithstanding a 4-fold difference in the mean Vmax values. This anomaly occurred in association with a large disparity in mean Km values, i.e. 68.3 +/- 1.6 (+/- SE) nmol/L in hyperplasia vs. 23.0 +/- 2.9 nmol/L in carcinoma. The dissociation between parameters of 5 alpha-reductase activity and tissue dihydrotestosterone concentrations was apparent to some extent in benign prostatic hyperplasia, in which the lowest stromal androgen concentrations were found in prostates with the largest Vmax and Km values; also, a rise in stromal Km was almost invariably associated with a proportional increase in Vmax (correlation coefficient = 0.95). These data strongly suggest that the stromal and epithelial forms of 5 alpha-reductase are separate isoenzymes, and that the excess of 5 alpha-reductase in stroma does not promote accumulation of an abnormal amount of dihydrotestosterone. They also imply that both the augmentation of 5 alpha-reductase activity in hyperplastic stroma and the condition of benign hyperplasia of the prostate are mutual consequences of a primary increase in Km.