Seasonal variation in the feeding ecology of the grey-cheeked mangabey (Lophocebus albigena) in Cameroon

Seasonal fluctuations in resource abundance often cause primates to change their feeding behavior and ecology. The objective of this study was to examine the response of a largely frugivorous monkey, the grey-cheeked mangabey (Lophocebus albigena), to seasonal variations in fruit abundance. We used 15-min scan sampling to quantify feeding, activity, and habitat use by monkeys between February and December 1998 in the Dja Reserve, Cameroon. L. albigena were found to have omnivorous feeding habits, consuming the fruits, seeds, leaves, and flowers of 132 plant species. Although monkeys fed from many plant species, only five plant species accounted for 45% of all feeding records. The number of feeding observations on a plant species was significantly correlated with its fruit production. L. albigena responded to fruit-lean periods by shifting from a diet dominated by fruit to one dominated by seeds, flowers, and young leaves. This diet shift coincided with greater use of swamp habitat and higher dietary diversity. L. albigena spent the greatest percentage of scan samples feeding and traveling, but activities varied significantly over the day. Individuals spent a significantly higher percentage of scan samples feeding during the fruit-rich season than in the fruit-lean season. Comparing our results to those of studies in Gabon and Uganda, we found that L. albigena differ across regions in the number of plant species they consume and time spent feeding. These differences may be a result of variations in tree diversity or the strength of seasonal fluctuations in resource abundance among sites.

alpha-adducin and angiotensin I-converting enzyme polymorphisms in essential hypertension

This study focused on two genes that have previously been implicated in hypertension and may influence renal sodium handling, adducin, and angiotensin I-converting enzyme (ACE). We compared their polymorphic frequencies and interaction in patients with essential hypertension (n=128) and individually age- and gender-matched normotensive control subjects. The alpha-adducin G460W polymorphism was genotyped by DNA amplification and restriction digestion. The ACE I/D polymorphism was assayed by a triple-primer method, with a "nested" polymerase chain reaction primer situated completely within the insertion sequence of the I: allele. The distributions of genotypes and alleles for the two polymorphisms were not significantly different between the case and control populations, and the cross-classification of cases by alpha-adducin and ACE genotype gave a distribution similar to that of control subjects. We have previously reported that the distributions of genotypes for two linked polymorphisms in the aldosterone synthase gene (one in the steroidogenic factor-1 [SF-1] binding site and the other an intronic conversion [IC]) were significantly different between this cohort of essential hypertensives and matched control subjects. The cross-classification of cases by alpha-adducin and SF-1, alpha-adducin and IC, ACE and SF-1, and ACE and IC genotype gave a distribution similar to that of control subjects. Hence, no evidence was found to suggest an association between either the alpha-adducin G460W or the ACE I/D polymorphism and hypertension in a careful case-control study. Furthermore, the alpha-adducin G460W, ACE I/D, and aldosterone synthase SF-1 and IC polymorphisms do not appear to interact in our hypertensive population.

Using (1)H magnetic resonance imaging and complementary analytical techniques to characterize developmental changes in the Zantedeschia Spreng. tuber

Nuclear magnetic resonance imaging (MRI) and complementary analytical techniques were used to examine tissue structure and developmental changes occurring during active growth in the root tuber of ZANTEDESCHIA: Spreng. cv. Chianti, a commercially significant cut flower. Plants were observed during the period of leaf senescence and tuberization at the end of the first growth cycle of micropropagated plantlets and, following cool storage to break endodormancy, during development occurring after the replanting of ecodormant tubers. MRI distinguished two distinct regions within the tuber, and the differences in the binding state of water in the two regions were reflected in differences in tissue morphology and function. An abundance of free water was observed in tissue comprised of large parenchyma cells, at the base of the tuber. This tissue appeared to be involved in maintaining the viability of the plant during the period of dormancy, a function indicated primarily by increased metabolic activity in this tissue during dormancy, and reduced metabolic activity during periods of active growth. In contrast, water was more tightly bound in tissue comprised of small parenchyma cells. This tissue appeared to operate as a region for dynamic carbohydrate storage. The initial increase in the free water content of this tissue during the growth phase was linked to the mobilization of starch during canopy development. The subsequent decrease in free water in the remainder of the growth period was linked to the reaccumulation of starch while the tuber functioned as a sink for photosynthate prior to canopy senescence.

Corticosteroid production by fetal rat hippocampal neurons

11beta-hydroxylase and aldosterone synthase catalyse the final stages of corticosterone and aldosterone synthesis respectively. Previously, we established that they are expressed in the rat brain, particularly the cerebellum and the hippocampus. Primary cultures of fetal rat neurons were studied. RT-PCR and immunohistochemistry established that neurons express 11beta-hydroxylase and aldosterone synthase mRNAs and protein. After incubating the cells with 10microM DOC for 24 hours, medium was analysed for aldosterone and corticosterone. Median % conversion of DOC to corticosterone was 7.6% compared to 0.4% in controls. Median % conversion of DOC to aldosterone was 6.2% compared to 0.06% in controls. Corticosteroids mediate a number of functions of mammalian brain, including blood pressure homeostasis, salt appetite and neuronal excitability. Local production of these steroids could have significant effects on these processes.

Expression of 11beta-hydroxylase and aldosterone synthase genes in the rat brain

The terminal stages of cortisol and aldosterone production in the human adrenal gland are catalysed by the enzymes 11beta-hydroxylase and aldosterone synthase, which are encoded by the CYP11B1 and CYP11B2 genes respectively. Recent studies have suggested that aldosterone and cortisol are also made in other tissues such as the brain, heart and vascular system and may play a role in cardiovascular homeostasis. The aim of this study was to confirm the presence of these enzymes and localise them precisely in the rat brain. Reverse transcription-polymerase chain reaction (RT-PCR)/Southern blotting confirmed transcription of CYP11B1 and CYP11B2 in whole brain and hypothalamus minces from Wistar-Kyoto rats. 11beta-Hydroxylase and aldosterone synthase were immunolocalised in paraffin-embedded rat adrenal and brain sections using mouse monoclonal antibodies. Negative controls utilised a mouse monoclonal antibody raised against a non-mammalian epitope. In the brain, 11beta-hydroxylase and aldosterone synthase were detected in the cerebellum, especially the Purkinje cells, as well as the hippocampus. The specificities of the 11beta-hydroxylase and aldosterone synthase antibodies were confirmed by positive immunostaining of the relevant regions of the adrenal cortex. This is the first direct evidence that steroid hydroxylases involved in the final stages of corticosteroid biosynthesis are present in specific regions of the central nervous system.

Skeletal muscle strength and endurance in patients with mild COPD and the effects of weight training

This study poses two questions: 1) is there an abnormality in isokinetic skeletal muscle strength and endurance in mild chronic obstructive pulmonary disease (COPD)? and 2) what is the effect of a randomized, controlled, 12 week hospital outpatient weight training programme in terms of skeletal muscle function and exercise tolerance? Upper and lower limb isokinetic maximum and sustained muscle function were compared in 43 COPD patients (age 49+/-11 yrs), mean forced expiratory volume in one second (FEV1) 77+/-23% pred and 52 healthy, sedentary subjects (age 51 (10) yrs), mean FEV1 109+/-16% pred. The 43 COPD patients were randomly allocated into training (n=26) and control (n=17) groups. Isokinetic and isotonic muscle function, whole body endurance, maximal exercise capacity and lung function were measured. The COPD patients had reduced isokinetic muscle function (with the exception of sustained upper limb strength) as compared with healthy sedentary subjects. Muscle function improved after weight training in the COPD patients. Whole body endurance during treadmill walking also improved with no change in maximal oxygen consumption. A deficit in skeletal muscle function can be identified in patients with mild chronic obstructive pulmonary disease which cannot be explained by factors such as hypoxaemia and malnutrition. Intervention with weight training is effective in countering this deficit which the authors conclude is probably due to muscle deconditioning.

Article I: Prevention and education regarding rabies in human beings. National Working Group on Rabies Prevention and Control

Substantial changes in the epizootic characteristics of rabies have transpired in the United States during the past 50 years. Traditional veterinary practices and public health recommendations have effectively controlled rabies in dogs and prevented associated human fatalities; however, they have been unable to adequately address the problem of rabies in wildlife. Attributable in part to a renewed focus on emerging infectious diseases, a conference was held at the Centers for Disease Control and Prevention in 1993 to begin discussion focused on the reemergence of rabies and to formulate new suggestions for prevention and control of rabies in the United States. Three major working groups were formed from a national committee of professionals representing a broad array of biomedical disciplines. These groups concentrated on prevention of rabies in human beings, education, laboratory diagnosis of rabies, and rabies control in animals. The groups described the perceived minimum requirements to promote prevention and control of rabies in the United States into the next century. The following article describes the needs and recommendations identified by the prevention and education working group. Two other articles, scheduled for the Nov 15 and Dec 1, 1999 issues of JAVMA, will relay the needs and recommendations of the working groups on laboratory diagnosis of rabies and rabies in wildlife.

Physical activity and asthma

The relationship between asthma and exercise and the resultant disability (ie, the impact on activities of daily living, including physical activity) shows wide interpatient and intrapatient variability, being influenced not only by the disease but additional psychosocial variables. There are a variety of helpful pharmacologic and nonpharmacologic measures in dealing with simple exercise-induced asthma, and new therapeutic options are being developed. The cardiorespiratory performance characteristics of asthmatic patients are very frequently suboptimal, either because of symptom-limited exercise tolerance or secondary deconditioning consequent upon inactivity. Medically supervised physical training can produce significant beneficial change. Recommendations for rehabilitation of asthmatic patients would include individualized exercise prescription and advice based on objective criteria of exercise capability, with flexibility in the programs offered, in order to cater to the broadest spectrum of patient disability.

Treatment of endothelial cells with serum from women with preeclampsia: effect on neutrophil adhesion

OBJECTIVE

The purpose of our study was to determine whether the previously reported neutrophil activation that occurs in the maternal circulation of women with preeclampsia is due to a factor (or factors) in serum that increases neutrophil adhesion to endothelial cells.

METHODS

The extent of neutrophil adhesion to endothelial cells incubated with serum from women with preeclampsia (n = 12) was compared with serum from normal, pregnant women matched for maternal age and gestational age at blood sampling (n = 12). Preeclampsia was defined as persistent diastolic blood pressure above 90 mmHg, with proteinuria greater than 0.3 g per 24 hours, in patients who were normotensive before 20 weeks' gestation. The ability of serum (with and without heat inactivation of the complement system) from both groups of patients to stimulate neutrophil adhesion to endothelial monolayers was tested in a 15-minute quantitative assay using fluorescence-labeled neutrophils. The extent of neutrophil adhesion was quantified indirectly from fluorescence counts.

RESULTS

No significant differences were found regarding neutrophil-endothelial cell adhesion in response to media alone, serum from women with preeclampsia, and serum from normal, pregnant women. This was also the case when the serum was heat inactivated to destroy the complement system. However, heat inactivated serum produced a significantly greater extent of adhesion compared with serum containing an intact complement system, regardless of whether the patient had preeclampsia.

CONCLUSION

This study found no evidence of a factor in serum from women with preeclampsia that could alter neutrophil-endothelial cell adhesion via a direct effect on the endothelium. However, our data suggest that adhesion may be regulated in an inhibitory manner by the complement system.

Low intensity peripheral muscle conditioning improves exercise tolerance and breathlessness in COPD

This randomized, controlled study investigated the physiological effects of a specially designed 12 week programme of isolated conditioning of peripheral skeletal muscle groups. The programme required minimal infrastructure in order to allow continued rehabilitation at home after familiarization within hospital. Forty eight patients, aged 40-72 yrs with chronic obstructive pulmonary disease (COPD) (mean (SD) forced expiratory volume in one second (FEV1) 61 (27)% of predicted normal) were randomly allocated into training (n = 32) and control (n = 16) groups. Physiological assessments were performed before and after the 12 week study period, and included peripheral muscle endurance and strength, whole body endurance, maximal exercise capacity (maximum oxygen consumption (V'O2,max)) and lung function. The training group showed significant improvement in a variety of measures of upper and lower peripheral muscle performance, with no additional breathlessness. Whole body endurance measured by free arm treadmill walking increased by 6,372 (3,932-8,812) 3 (p < 0.001). Symptom-limited maximal V'O2 was unchanged. However, the training group showed a reduction in ventilatory equivalents for oxygen and carbon dioxide, both at peak exercise and at equivalent work rate (Wmax). In summary, low intensity isolated peripheral muscle conditioning is well-tolerated, simple and easy to perform at home. The various physiological benefits should enable patients across the range of severity of chronic obstructive pulmonary disease to improve daily functioning.

Sump bay fever: inhalational fever associated with a biologically contaminated water aerosol

OBJECTIVE

To investigate the clinical, serological, and environmental features of a work related inhalational fever associated with exposure to an aerosol generated from a biologically contaminated 130,000 gallon water pool in a building used for testing scientific equipment.

METHOD

Cross sectional survey of all exposed subjects (n = 83) by symptom questionnaire, clinical examination, spirometry, and serology for antibody to Pseudomonads, pool water extract, and endotoxin. In symptomatic patients diffusion capacity was measured, and chest radiology was performed if this was abnormal. Serial peak flow was recorded in those subjects with wheeze. Bacterial and fungal air sampling was performed before and during operation of the water pool pump mechanism. Endotoxin was measured in the trapped waters and in the pumps. Serum cotinine was measured as an objective indicator of smoking.

RESULTS

Of the 20 symptomatic subjects, fever was most common in those with the highest exposure (chi 2 42.7, P < 0.001) in the sump bay when the water was (torrentially) recirculated by the water pumps. Symptoms occurred late in the working day only on days when the water pumps were used, and were independent of the serum cotinine. Pulmonary function was normal in most subjects (spirometry was normal in 79/83, diffusion capacity was low in five subjects, chest radiology was normal). Peak flow recording did not suggest a work relation. The bacterial content of the aerosol rose from 6 to > 10,000 colony forming units per cubic metre (cfu/m3) (predominantly environmental Pseudomonads) when the pumps were operating. High endotoxin concentrations were measured in the waters and oil sumps in the pumps. Low concentrations of antibody to the organisms isolated were detected (apart from two subjects with high antibody) but there was no relation to exposure or the presence of symptoms and similar antibody was found in the serum samples from a non-exposed population. The fever symptoms settled completely with the simple expedient of changing the water and cleaning the pumps.

CONCLUSION

Given the results of our study, the development of inhalational fever in this unique environment and clearly restricted cohort was closely related to the degree of exposure to contaminated aerosol and mainly occurred in the absence of distinct serological abnormality and independent of cigarette smoking.

Efficiency of sampling: birthweight and gestational age distributions in two cohorts, < 31 weeks and 500-1499 grams

We studied the efficiency of two common sampling strategies used to assemble cohorts to study the long-term problems of preterm infants: infants with birthweights of 500-1499 g, and infants with gestational ages (GA) of < 31 weeks. Birthweight, GA and 2-year outcome data from a population based study of infants < 2001 g, the Central New Jersey Brain Hemorrhage Study (NBH), were used to define the birthweight and GA distributions, at enrollment and at the age of 2 years, of overlapping subsets: infants 500-1499 g (n = 599) and infants < 31 weeks of age (n = 522). Using frequencies from the NBH study, we estimated that 1000 infants of 500-1499 g enrolled at birth would produce 712 infants at the age of 2 years, 498 below 31 weeks and 214 above. Enrolling 1000 infants < 31 weeks would produce a cohort of 697 infants at the age of 2, all of whom were < 31 weeks. Neither sampling strategy maximised the statistical power to investigate the pathophysiological determinants of long-term outcomes associated with short GA. Both methods oversampled older GAs. A stratified sampling technique based on GA, designed to produce equal numbers of subjects at each week of GA, would improve statistical power to study long-term outcomes. As we move from descriptive to analytical studies of preterm infants, we need to devise efficient, GA-based, sampling strategies that maximise statistical power to test pathophysiological hypotheses.

Use of static and dynamic NMR microscopy to investigate the origins of contrast in images of biological tissues

NMR imaging experiments have been carried out on a fruit (Actinidia deliciosa) and plant stem (Stachys sylvatica) using a wide range of image contrasts. These included T1, T2, T2*, diffusion, flow and chemical shift selection. In the case of fruit imaging we calculated relaxation time and diffusion maps and established that the imaged parameters varied significantly with fruit ripening. These changes we attribute to changes in water dynamics resulting from elevated sugar concentrations. For the plant stem, water flow has been observed in the xylem vessels with a maximum velocity of 70 microns s-1. The role of image artifacts is considered and, in the case of transverse relaxation, we have demonstrated that it is necessary to use a precursor Carr-Purcell-Meiboom-Gill pulse train if additional diffusive attenuation is to be avoided.

The influence of education on morbidity and mortality in asthma (including the use of open access hospital admission for severe attacks)

Despite the availability of effective drugs, asthma morbidity and mortality are increasing. Undertreatment is a significant contributory factor providing the rationale for improved concentration on education of asthmatics. A review of asthma education programmes reveals improvements in a variety of outcome measures. However, the types of patients studied in these programmes are very variable and it remains an unproven assumption that previously non-compliant and undertreated patients are amenable to improving asthma through education. The problems of compliance are common both in childhood and adult asthma. Further concentration on strategies to improve the management of this particular sub-group require development. In general, education programmes appear more effective when they consist of specific self-management instructions rather than general education regarding the disease process.

The place of education in the management of chronic lung disease

Health education, although an interesting logical requirement for management of chronic lung disease, is a complete process. It consists of more than transmission of a message with the expectation of implementation. The core materials can easily be identified, but the patient's response cannot be anticipated. Education of the health care providers, in this context respiratory physicians, regarding the second stage, should help to improve outcome.

Guanine nucleotide regulatory protein alterations in young Milan hypertensive strain rats

Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normotensive strain (MNS) membranes. Forskolin (10(-4) M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10(-2) M). Isoproterenol (10(-4) M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E1 (10(-5) M) produced similar responses in the two strains. Gi function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of Gi2 alpha and Gq alpha/G11 alpha were similar in the two strains, while the levels of Gs alpha (44 and 42 kDa forms) and the beta-subunit were significantly reduced by approximately 20% in MHS membranes. The alpha-subunit of Gi3 was dramatically reduced by approximately 80% in MHS membranes. The affinities of beta-adrenergic receptors for the antagonist, cyanopindolol, were similar in the two strains; however, the number of beta-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS.

Guanine nucleotide regulatory protein alterations in the Milan hypertensive rat strain

OBJECTIVE

To examine whether the altered regulation of adenylyl cyclase that has been reported in vascular tissues from spontaneously hypertensive rats is also evident in the Milan hypertensive (MHS) rat strain.

DESIGN

The plasma membranes of vascular smooth muscle cells derived from thoracic aortae from adult (60-day-old) MHS and Milan normotensive (MNS) strain rats were studied.

METHODS

Guanine nucleotide regulatory protein (G-protein) function was inferred from adenylyl cyclase activity studies, and levels of G-protein subunits were assessed by immunoblotting. beta-Adrenergic receptor number and affinity were measured from the binding of the antagonist [125I]-cyanopindolol.

RESULTS

Basal adenylyl cyclase activity was increased significantly in MHS rat cell membranes, and stimulation by 0.1 mmol/l isoproterenol and 0.01 mmol/l prostaglandin E1 was significantly greater in MHS than in MNS rat cell membranes. Forskolin (at 0.1 mmol/l) resulted in a significantly greater stimulatory response in MHS membranes, which was eliminated by 0.01 mol/l NaF. Biphasic effects of GTP on isoproterenol-stimulated membranes demonstrated similar Gi function in MHS and MNS rat cell membranes, although a greater stimulatory GTP response was observed in MHS rat cell membranes. The levels of Gs alpha (both forms), Gi3 alpha and the beta-subunit were reduced in MHS rat cell membranes, whereas the levels of Gi2 alpha and Gq alpha and G11 alpha were unchanged. The number of beta-adrenoceptors was increased significantly in MHS rat cell membranes, whereas receptor affinity for the antagonist was unaltered.

CONCLUSIONS

There are differences in adenylyl cyclase stimulatory responses in MHS rat vascular smooth muscle cell membranes. We have found evidence of reduced levels of particular G-protein subunits, altered beta-adrenoceptor-Gs coupling and increased beta-adrenoceptor number.

Guanine nucleotide regulatory proteins in the spontaneously hypertensive rat

We compared guanine nucleotide regulatory protein (G protein) levels and function in plasma membranes from resistance vessels (mesenteric arteries) isolated from spontaneously hypertensive (SHR) and normotensive Wistar rats. G protein function was deduced from studies of adenylate cyclase activity. Although the basal level of adenylate cyclase activity (+/- Mn2+ ions) was significantly greater in SHR membranes, addition of agents that function via the stimulatory G protein--i.e., NaF (10(-2) M), (-)-isoproterenol (10(-4) M), and prostaglandin E1 (10(-5) M)--resulted in a significantly lower stimulatory response in SHR membranes. Ligands that function via the inhibitory G protein--i.e., adrenaline (10(-5) M)/propranolol (10(-5) M) (this combination being equivalent to an alpha 2-receptor agonist), carbachol (10(-3) M), and serotonin (10(-5) M)--were responsible for only slight inhibitory responses in both SHR and Wistar rat membranes, which were not significantly different. Western blotting identified the presence of Gs, Gi2, and Gi3 alpha-subunits in rat vascular smooth muscle, but there were no differences in the levels of these G protein alpha-subunits found in SHR and Wistar rat plasma membranes. The levels of the beta-subunit in the two sets of membranes were also similar. In conclusion, there is a reduced response in adenylate cyclase activity to agents that function via the stimulatory G protein in SHR membranes. However, this is not a consequence of altered levels of the different G protein subunits.