Developing a Microcomputer Based Automated Testing System for use with Psychogeriatric Patients

Microcomputers are increasingly being used in psychiatry for a variety of purposes. When used in computer-patient ‘interviews’ they have generally proved acceptable—indeed popular—with psychiatric patients. Automated psychological assessment is one form of computer-patient interview that is attracting much interest. Some of the early applications were with elderly patients. Kendrick has expressed doubts regarding this application with the current generation of elderly people, suggesting that their relative unfamiliarity with computers and video games might cause difficulties.

Molecular tagging of a senescence gene by introgression mapping of a stay-green mutation from Festuca pratensis

* Intergeneric hybrids between Lolium multiflorum and Festuca pratensis (Lm/Fp) and their derivatives exhibit a unique combination of genetic and cytogenetic characteristics: chromosomes undergo a high frequency of homoeologous recombination at meiosis; the chromosomes of the two species can easily be discriminated by genomic in situ hybridization (GISH); recombination occurs along the entire length of homoeologous bivalents; a high frequency of marker polymorphism is observed between the two species. * This combination of characters has been used to transfer and isolate a F. pratensis chromosome segment carrying a mutant 'stay-green' gene conferring a disrupted leaf senescence phenotype into L. multiflorum. * The genetic location within the introgressed F. pratensis segment of the senescence gene has been mapped using amplified fragment length polymorphisms (AFLPs), and F. pratensis-specific AFLP markers closely flanking the green gene have been cloned. * The use of these cloned sequences as markers for the stay-green locus in marker-assisted selection programmes has been tested. The potential application of Lm/Fp introgressions as a tool for the map-based cloning of introgressed Fp genes is discussed.

Interleukin-1 beta rapidly inhibits aortic endothelium-dependent relaxation by a DNA transcription-dependent mechanism

OBJECTIVES

This study examined the effects of interleukin-1 beta on isometric tension development and relaxation in isolated rat aortic rings in response to the alpha-1 adrenergic agonist phenylephrine, the endothelium-dependent vasodilator acetylcholine, and the endothelium-independent vasodilator sodium nitroprusside.

DESIGN

Randomized, controlled, paired design.

SETTING

Animal laboratory within a university department of physiology. SUBJECTS Paired aortic thoracic aortic rings from specific pathogen-free Sprague-Dawley rats.

INTERVENTIONS

Series I examined the potential for interleukin-1 beta to cause early arterial endothelial dysfunction. Paired aortic rings were incubated for 2 hrs with interleukin-1 beta or vehicle. Series II examined the potential for inhibition of DNA transcription to attenuate interleukin-1 beta-mediated endothelial dysfunction. Paired rings received either dactinomycin or vehicle before interleukin-1 beta incubation. Series III quantified the degree to which inhibition of DNA transcription inhibited early interleukin-1 beta-mediated endothelial dysfunction. Paired rings received either dactinomycin pretreatment followed by interleukin-1 beta incubation, or pretreatment and incubation with inert vehicles. Series IV assessed the effects of interleukin-1 beta on responsiveness to an exogenous nitric oxide donor, sodium nitroprusside, in the presence of the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester.

MEASUREMENTS AND MAIN RESULTS

Incubation with interleukin-1 beta for 2 hrs had no effect on contractile response but attenuated endothelium-dependent relaxation significantly relative to control. Dactinomycin pretreatment inhibited early interleukin-1 beta-mediated endothelial dysfunction. The combination of interleukin-1 beta and dactinomycin produced effects on endothelium-dependent relaxation that were not different from that seen in rings not exposed to interleukin-1 beta. Interleukin-1 beta attenuated responsiveness to sodium nitroprusside relative to control.

CONCLUSIONS

Interleukin-1 beta causes an early impairment of endothelium-dependent vasorelaxation with an onset that precedes its effects on systemic contractility. This impairment occurs via a mechanism that is wholly or predominantly dependent on DNA transcription. The altered vasorelaxation induced by interleukin-1 beta is at least partly mediated by a reduction in nitric oxide responsiveness.

Abatement of gas-condensate hydrocarbons in a natural wetland

Results of a five-year research study on natural attenuation processes in a wetland, located downgradient of a sour gas processing plant in central Alberta, Canada, show that natural attenuation may present a favourable remedial solution. Both free-phase and dissolved phase condensate have been discharging to the wetland since 1984. This condensate is primarily composed of C5 to C12 hydrocarbons, including BTEX compounds. The condensate enters the base of the wetland at 1 m below ground surface, resulting in contamination of the wetland peat and underlying clay till. The lateral extent of contamination in the wetland has remained stable, and apparent free product thickness and BTEX concentrations have decreased over time. Sorption, aerobic biodegradation, volatilization, and anaerobic biodegradation were identified as active attenuation processes at this site. Sorption and desorption processes were evaluated by laboratory testing of site soils using 14C-benzene. Linear sorption coefficients (Kd) for the surface and subsurface peat were similar (4.48-4.62 l/kg), while the Kd for the underlying silt was 0.096 l/kg. The significantly higher Kd values for the peat are attributed to the peat's higher organic content (40%), relative to the clayey silt (1%). No significant resistance to desorption was observed, however, indicating that benzene would remain mobile and bioavailable over time. Aerobic biodegradation and volatilization appear to be the main removal processes. They are enhanced by a seasonal drop in the water level from surface down to 1 m depth, resulting in an aerobic unsaturated zone. Respiration testing in the peat indicates a significant aerobic biodegradation rate of 27 mg/kg/day, equating to an estimated hydrocarbon removal rate of 5 kg/day across the 3600 m2 plume area. Surface vapour measurements indicate hydrocarbon volatilization is occurring at a rate of 3 x 10(-4) kg/m2/day, equating to a mass removal of 1 kg/day across the plume. Anaerobic biodegradation is occurring primarily in the clayey silt, based on geochemical indicator parameters, microbial analyses, and soil vapour sampling. Overall, natural attenuation appears to be a feasible remedial solution for this wetland, by providing continued removal and degradation of condensate components before they reach the downgradient surface water receptor.

Airway narrowing associated with inhibition of deep inspiration during methacholine inhalation in asthmatics

Reduced bronchodilatation in response to deep inspiration (DI) has been demonstrated in asthmatics. We have previously shown that inhibition of DI for 10 min or more during methacholine inhalation increases airway narrowing in normals. We tested the hypothesis that inhibition of DIs during methacholine inhalation in asthmatics would not affect the magnitude of airway narrowing. We administered the PC(15) dose of methacholine to eight asthmatics every 5 min for 5 doses and measured spirometry after each dose. On four separate days, subjects received either 2, 3, 4, or 5 doses selected randomly, but DIs were inhibited during the challenge and spirometry was measured only at the start and after the final dose. Geometric mean PC(15) was 1.6 mg/ml. Mean values for FEV(1) (+/- SEM) after Doses 2 through 5 were 84 +/- 4, 78 +/- 6, 79 +/- 5, and 81 +/- 3% of baseline, respectively, when DIs were allowed. During inhibition of DIs, they were 73 +/- 6, 67 +/- 5, 64 +/- 6, and 61 +/- 7% of baseline values. Decreases in FEV(1) after Doses 4 and 5 were significantly greater when DIs were inhibited (p < 0.05). We conclude that in this group of asthmatics, inhibition of DI for 15 min is associated with increased airway narrowing in response to methacholine inhalation, and therefore, DI may be an important factor limiting induced airway narrowing in asthmatics as well as in normal subjects.

Socioeconomic issues affecting the treatment of obesity in the new millennium

The prevalence of obesity among the populations of most developed countries has increased to such an extent that the healthcare and social security/disability system will accumulate direct and indirect costs related to obesity that will be more substantial than those for any other primary disease within this generation. For the past decade, the Healthcare Financing Agency, which oversees the Medicare and Medicaid programmes, has required all physicians and healthcare agencies serving beneficiaries of these programmes to include diagnoses using codes established by the ninth revision of the World Health Organization's International Classification of Diseases. This coding system actually distorts data collection and undermines appropriate medical insurance reimbursement for the treatment of obesity. Societal prejudices, inability of governmental agencies to address future concerns and the business community's attempts to control healthcare costs without addressing the underlying issues contributing to these costs have led to confusion on how to confront this emerging epidemic. How will we develop the scientific knowledge and the political willpower to confront this epidemic? First, we need more accurate methods for classifying obesity and for measuring the cost of treatment. We can then determine if it is more cost effective to prevent or treat obesity early in its evolution or pay for its consequences in the form of treatment costs associated with its multiple comorbid diseases, such as hypertension, other cardiovascular disorders, diabetes mellitus, osteoarthritis and cancers, plus the lost productivity from absenteeism, premature retirement and death.

Time course of increased airway narrowing caused by inhibition of deep inspiration during methacholine challenge

Inhibition of deep inspiration (DI) enhances methacholine-induced airway narrowing in normal subjects. However, the time course over which excessive airway narrowing develops during inhibition of DI is not known. We hypothesized that the development of enhanced airway narrowing when DI is inhibited is time dependent. Ten normal volunteers (five males and five females) inhaled five doses of methacholine (16 mg/ml for 2 min) at 5-min intervals during an initial methacholine challenge. FEV(1) was measured at baseline and after each dose. On four subsequent days, the subjects again inhaled two, three, four, or five doses, in random order, without DIs during the challenge. FEV(1) was measured only at baseline and after the last dose. Baseline FEV(1) was normal in all subjects. The maximal mean percent decrease in FEV(1) after the initial challenge was 10 +/- 1.5%, but was 28 +/- 6.0% when DIs were inhibited throughout the five inhalations (p < 0.01). The difference in decrease in FEV(1) between days with and without DI became significant after 10 min (three doses), and remained stable thereafter when the response plateaued. The reversal of airway narrowing after three DIs was incomplete after 15 min (four doses). In conclusion, the increased airway narrowing associated with inhibition of DI during airway smooth-muscle contraction occurs after 10 min in normal subjects, at which time the response plateaus. However, the ability of DI to reverse airway narrowing appears to diminish progressively.

Mechanism of methacholine dose-response plateaus in normal subjects

Normal subjects develop plateaus on dose-response curves produced from inhalation challenge tests with bronchoconstricting agonists. These plateaus occur after only mild degrees of airway narrowing despite the fact that, if unloaded, maximally activated airway smooth muscle (ASM) should be able to cause airway closure. Plateaus may develop because, despite maximal activation, the muscle load provided by lung parenchymal recoil and tidal swings in airway transmural pressure are sufficient to prevent further ASM shortening. Alternatively, progressive ASM activation may occur throughout the plateau, but progressive hyperinflation and/or parenchymal stiffening could increase parenchymal load and attenuate further airway narrowing. In the first case, maximal ASM activation causes the plateau and in the second case the plateau is caused by progressive activation balanced by progressive loading. To test which of these mechanisms is responsible for the plateau, we measured pulmonary resistance (RL) and the maximal, minimal, and mean pulmonary elastic recoil pressure (PELmax, PELmin, and PELmean) during tidal breathing throughout methacholine challenge in 10 normal subjects. PELmean served as our measure of ASM afterload. Subjects swallowed an esophageal balloon and inhaled doubling concentrations of methacholine (1 to 256 mg/ml). RL was measured after each dose, as was PEL. All subjects developed a plateau on the dose-response curve defined by < 25% change in RL over three successive doses. During the RL plateau, there was no significant further increase in PELmean, i.e., PELmean also plateaued. These data are consistent with the hypothesis that maximal activation of ASM is balanced by an equal afterload at the maximal dose-response plateau. Airway hyperresponsiveness could result from a failure of afterload to attenuate muscle shortening after maximal activation.

Ferrets (Mustela putoius furo) inefficiently convert beta-carotene to vitamin A

The ferret has recently been used as a model to evaluate the absorption and metabolism of several carotenoids; however, little is known about the vitamin A (VA) requirements of this species or the ability of ferrets to convert dietary beta-carotene (betaC) to VA. Three studies were conducted to estimate the daily utilization of VA in ferrets and to determine the effect of prior VA status on the ability of ferrets to utilize betaC as a source of VA. Weanling male ferrets were fed a pelleted, low carotenoid, semipurified diet either with (+VA) or without VA (-VA) for 21- to 35-d prefeeding periods. Upon initiation of the experiments, several ferrets were killed to determine base-line VA status. The remaining ferrets were fed VA, betaC, or VA and betaC in pelleted feed (Studies 1-3) or liquid carrier (Study 3) for 16-21 additional days. Hepatic VA and betaC concentrations were used as the primary indicators of VA status, although serum and adrenal VA and betaC also were measured. The results showed the following: 1) provision of betaC at up to a 15:1 weight ratio of betaC to VA in pelleted feed or liquid carrier was not sufficient to maintain hepatic VA stores after a -VA prefeeding period; 2) the daily utilization rate of VA by ferrets ranged from 80 to 171 microg in the three studies; 3) the ferret was confirmed to be a species that has the majority of its serum VA in ester form; and 4) feeding -VA diets significantly reduced serum retinyl esters but had less effect on serum retinol. We conclude that although ferrets can convert betaC to VA, the process is inefficient. The ferret model can be most appropriately used when studying the biological effect of tissue betaC stores on VA status and is less appropriate for the evaluation of dietary betaC conversion to VA.

The effect of deep inspiration on methacholine dose-response curves in normal subjects

Normal subjects develop exaggerated airway narrowing when deep inspiration (DI) is voluntarily suppressed during methacholine challenge. Failure of periodic inflation may interfere with the bronchodilating effect of DI, and this may be fundamental to the difference in bronchodilation caused by DI in asthmatics and normal subjects. To determine whether repeated exhalations to residual volume (RV) and/or incomplete inspiration to baseline total lung capacity (TLC) could contribute to exaggerated narrowing during challenge, we tested 10 subjects on three separate days using modified methacholine challenge protocols. On Day 1, partial and complete flow volume curves were obtained after each dose. On Day 2, DI was prohibited, but partial curves were performed. On Day 3, DI and exhalation to RV were prohibited. TLC was measured pre- and post-challenge on each day. After comparable doses of methacholine, there was a greater change in FEV1 on Day 2 (27+/-15) and Day 3 (38+/-17) than on Day 1 (14+/-8) (p < 0.05). There were no differences in changes in FEV1 and FVC between Days 2 and 3, or in TLC between all 3 d. We conclude that exaggerated airway narrowing occurs in normal subjects when DI is prohibited and that this effect is not due to repeated expiration to RV, nor due to an artifact caused by a failure to inhale to TLC.

Integration of 101 DNA markers across human Xp11 using a panel of somatic cell hybrids

One hundred and one DNA markers previously assigned to the short arm of the human X chromosome were localized on a hybrid mapping panel consisting of ten radiation-reduced, and four classical somatic cell hybrids. Of the 101 DNA markers, 16 are genes, two are pseudogenes, 13 are expressed sequence tags, 32 are simple tandem repeats (STRs), four are restriction fragment length polymorphisms, one is a variable number of tandem repeats, and 33 are sequence tagged sites (STSs). Three of these markers, two STSs and one STR, were generated from the products of an inter-Alu PCR library of a radiation-reduced hybrid containing Xp11.4-->p11.22 as its only human DNA content. A second STR was isolated from a region-specific cosmid containing the gene ZNF21. The 101 DNA markers fell into 22 bins based on their retention on the hybrids of this panel, which, in combination with YAC contig data, could be further resolved into 24 bins. This hybrid map of Xp11 has an average resolution of approximately 0.8 Mb.

cis-trans lycopene isomers, carotenoids, and retinol in the human prostate

An evaluation of the Health Professionals Follow-Up Study has detected a lower prostate cancer risk associated with the greater consumption of tomatoes and related food products. Tomatoes are the primary dietary source of lycopene, a non-provitamin A carotenoid with potent antioxidant activity. Our goal was to define the concentrations of lycopene, other carotenoids, and retinol in paired benign and malignant prostate tissue from 25 men, ages 53 to 74, undergoing prostatectomy for localized prostate cancer. The concentrations of specific carotenoids in the benign and malignant prostate tissue from the same subject are highly correlated. Lycopene and all-trans beta-carotene are the predominant carotenoids observed, with means +/- SE of 0.80 +/- 0.08 nmol/g and 0.54 +/- 0.09, respectively. Lycopene concentrations range from 0 to 2.58 nmol/g, and all-trans beta-carotene concentrations range from 0.09 to 1.70 nmol/g. The 9-cis beta-carotene isomer, alpha-carotene, lutein, alpha-cryptoxanthin, zeaxanthin, and beta-cryptoxanthin are consistently detectable in prostate tissue. No significant correlations between the concentration of lycopene and the concentrations of any other carotenoid are observed. In contrast, strong correlations between prostate beta-carotene and alpha-carotene are noted (correlation coefficient, 0.88; P < 0.0001), as are correlations between several other carotenoid pairs, which reflects their similar dietary origins. Mean vitamin A concentration in the prostate is 1.52 nmol/g, with a range of 0.71 to 3.30 nmol/g. We further evaluated tomato-based food products, serum, and prostate tissue for the presence of geometric lycopene isomers using high-performance liquid chromatography with a polymeric C30 reversed phase column. All-trans lycopene accounts for 79 to 91% and cis lycopene isomers for 9 to 21% of total lycopene in tomatoes, tomato paste, and tomato soup. Lycopene concentrations in the serum of men range between 0.60 and 1.9 nmol/ml, with 27 to 42% all-trans lycopene and 58 to 73% cis-isomers distributed among 12 to 13 peaks, depending upon their chromatographic resolution. In striking contrast with foods, all-trans lycopene accounts for only 12 to 21% and cis isomers for 79 to 88% of total lycopene in benign or malignant prostate tissues. cis Isomers of lycopene within the prostate are distributed among 14 to 18 peaks. We conclude that a diverse array of carotenoids are found in the human prostate with significant intra-individual variation. The presence of lycopene in the prostate at concentrations that are biologically active in laboratory studies supports the hypothesis that lycopene may have direct effects within the prostate and contribute to the reduced prostate cancer risk associated with the reduced prostate cancer risk associated with the consumption of tomato-based foods. The future identification and characterization of geometric lycopene isomers may lead to the development of novel agents for chemoprevention studies.

Shape and position of the complete dose-response curve for inhaled methacholine in normal subjects

Plateaus on the inhalation concentration-response curve have been described in normal subjects and patients with mild asthma. To determine the prevalence of plateaus on inhalation concentration-response curves, and the position of the curves in normal subjects, we measured complete dose-response curves for methacholine (1 mg/ml to 256 mg/ml) in 73 nonatopic, nonsmoking, nonasthmatic normal subjects between the ages of 20 and 76 yr. Measurements included FEV1, maximal expiratory flow at 50% and 30% of vital capacity on partial and complete forced expiratory flow-volume curves (Vmax50p, Vmax50c, Vmax30p, Vmax30c) and pulmonary resistance (RL). Plateau responses, EC50 values and slopes were measured. Plateaus were present in 25, 27, 24, 34, 35, and 16 subjects for FEV1, Vmax50c, Vmax30c, Vmax50p, Vmax30p, and RL, respectively. In those who achieved a plateau, the mean maximal decrease in FEV1 (+/- SD) was 21 +/- 8%, in Vmax50c it was 46 +/- 16%, in Vmax50p it was 67 +/- 12%, in Vmax30c it was 58 +/- 21%, and in Vmax30p it was 75 +/- 15%, and the increase in RL was 213 +/- 89%. In summary, the results of this study showed that easily identifiable plateaus develop on the inhalation concentration-response curves of approximately 40% of normal subjects after only moderate decreases in maximum flow and increases in RL. Maximal response at the plateau was greater on partial flow-volume curves and at lower lung volumes (30% versus 50% of VC). Comparison of these data with data from patients at risk for airway hyperresponsiveness will allow definition of the mechanisms leading to airway hyperresponsiveness.

Measurement of lung expansion with computed tomography and comparison with quantitative histology

The total and regional lung volumes were estimated from computed tomography (CT), and the pleural pressure gradient was determined by using the milliliters of gas per gram of tissue estimated from the X-ray attenuation values and the pressure-volume curve of the lung. The data show that CT accurately estimated the volume of the resected lobe but overestimated its weight by 24 +/- 19%. The volume of gas per gram of tissue was less in the gravity-dependent regions due to a pleural pressure gradient of 0.24 +/- 0.08 cmH2O/cm of descent in the thorax. The proportion of tissue to air obtained with CT was similar to that obtained by quantitative histology. We conclude that the CT scan can be used to estimate total and regional lung volumes and that measurements of the proportions of tissue and air within the thorax by CT can be used in conjunction with quantitative histology to evaluate lung structure.

Donor selection limits use of living-related liver transplantation

The purpose of this investigation was to assess the applicability of living-related liver transplantation in an established regional transplant program by determining the frequency of acceptable living donors from an unselected population of pediatric transplant candidates and identify specific factors limiting application of this technique. During the period May 1992 to May 1994, all children accepted as transplant candidates at the University of California-San Francisco were evaluated for potential living-related liver transplantation. Indications for transplantation and patient demographics represented the spectrum anticipated at a regional center. Donor evaluation was performed using a three-phase evaluation process we have previously reported. Retrospective analysis identified 75 potential donors for 38 pediatric candidates (age range, 17 days to 14.5 years; mean, 5.1 years). Twenty-three percent of potential donors declined evaluation. Of the 75 potential donors, only 10 (13%) were found to be acceptable for donation. The leading causes for donor declination were significant medical history (23%), ABO blood group incompatibility (23%), and psychosocial history (20%). Of the 38 recipient candidates, 9 (23%) were offered living-donor transplantation. Five patients have received living-donor transplantation, and 4 patients await the procedure when medical indications exist. Seventy-seven percent of recipient candidates received or are awaiting cadaveric transplantation. These results suggest that current donor criteria markedly limit the application of living-related liver transplantation.

Donor selection limits use of living-related liver transplantation

The purpose of this investigation was to assess the applicability of living-related liver transplantation in an established regional transplant program by determining the frequency of acceptable living donors from an unselected population of pediatric transplant candidates and identify specific factors limiting application of this technique. During the period May 1992 to May 1994, all children accepted as transplant candidates at the University of California-San Francisco were evaluated for potential living-related liver transplantation. Indications for transplantation and patient demographics represented the spectrum anticipated at a regional center. Donor evaluation was performed using a three-phase evaluation process we have previously reported. Retrospective analysis identified 75 potential donors for 38 pediatric candidates (age range, 17 days to 14.5 years; mean, 5.1 years). Twenty-three percent of potential donors declined evaluation. Of the 75 potential donors, only 10 (13%) were found to be acceptable for donation. The leading causes for donor declination were significant medical history (23%), ABO blood group incompatibility (23%), and psychosocial history (20%). Of the 38 recipient candidates, 9 (23%) were offered living-donor transplantation. Five patients have received living-donor transplantation, and 4 patients await the procedure when medical indications exist. Seventy-seven percent of recipient candidates received or are awaiting cadaveric transplantation. These results suggest that current donor criteria markedly limit the application of living-related liver transplantation.

Developmental changes in diaphragm contractile properties

The contractile properties of pre- and early postnatal respiratory muscles are incompletely understood. We examined the effects of development on isometric contractile properties, with an emphasis on properties at 37 degrees C. One-day-old (n = 10), 3-wk-old (n = 10), and adult (n = 10) rabbits were studied. Isometric contractile properties of costal diaphragm strips were measured in vitro by using direct stimulation. Twitch and maximal, i.e., fused, tetanic force production increased with strip dimension and with age. Maximal tetanic force developed per unit cross-sectional area (stress) was significantly decreased in muscle from 1-day olds, whereas it was greatest in muscle from 3-wk olds. Twitch stress was similar in all three groups. Only when the stimulus duration was prolonged did twitch and fused tetanic force achieve maximal values values for the 1-day-old and 3-wk-old strips, suggesting less effective excitation-contraction coupling in those muscles. We conclude that immature rabbit diaphragm has unique isometric contractile properties and stimulus parameter requirements that cannot be deduced from studies using mature diaphragm.

Epithelial reorganization and irregular growth following carbendazim-induced injury of the efferent ductules of the rat testis

Occlusions of the rat efferent ductules were induced by an oral gavage of carbendazim and the capacity for regeneration or recanalization of the ductules was histologically evaluated between 2 and 70 days post-treatment. At 2 days post-treatment, the efferent ductules were occluded by sloughed materials and showed various degrees of inflammation. Severely damaged epithelium showed few regenerative features at later intervals. On the other hand, epithelia with medium inflammation often exhibited irregular epithelial growth along the luminal contents or the formation of multiple abnormal ductules. These abnormal ductules were formed by migrated and original epithelia at the periphery of the occluded lumen at 16 days post-treatment, indicating attempted recanalization. At later time periods, 32 and 70 days post-treatment, the occluded original lumen was filled in by fibrotic connective tissue and surrounded by a series of abnormal ductules. These abnormal ductules were characterized by cuboidal epithelia, a small luminal diameter, fewer cilitated cells than normal, less developed organelles in the epithelial cells, and basal laminae of irregular thickness. However, there was no evidence that occluded ductules formed patent re-connections via abnormal ductules. The results suggest that occluded efferent ductules have the ability to initiate epithelial regrowth and to form new ductules, but the newly formed ductules are abnormal and are not adequate to recover from azoospermia at least at 70 days post-treatment.

Acute and long-term effects of a single dose of the fungicide carbendazim (methyl 2-benzimidazole carbamate) on the male reproductive system in the rat

The effects of carbendazim (methyl 2-benzimidazole carbamate) on the testis, efferent ductules, and sperm were determined in the adult rat after a single oral dose. Two experimental trials were performed: a time response between 2 hours and 32 days after exposure using 0 and 400 mg/kg, and a dose response at 2 and 70 days after exposure using 0 to 800 mg/kg doses. In experiment 1, effects were seen throughout the 32-day period, beginning 8 hours after exposure; the effects included first an increase in testis weight, then decreases in testicular spermatid numbers and in the percentage of morphologically normal cauda sperm. In experiment 2, significant testicular and efferent ductal alterations occurred in animals treated with doses of 100 mg/kg or greater. A dose-dependent increase in testicular weight 2 days after treatment was accompanied by increases in seminiferous tubular diameter and excessive loss of immature germ cells in a stage-dependent manner. There was also a dose-dependent increased incidence of occlusions in the efferent ductules. The occluded ductules were characterized by severe inflammation and exhibited disorganization of the epithelium. At 70 days, there were dose-dependent decreases in mean testis weight and mean seminiferous tubular diameter; however, only minimal long-term effects were seen at 50 mg/kg. In testes exhibiting seminiferous tubular atrophy of greater than 25% (100 mg/kg or greater doses), all of the testes were associated with efferent ductules containing occlusions. Caput sperm numbers were significantly reduced in these testes. Occlusions, abnormal ductules, fibrosis, spermatic granulomas, and mineralization were observed in the ductuli efferents. Long-term effects of carbendazim on the testis were induced primarily by ductal occlusions. Results show that carbendazim produces more severe short- and long-term effects on the male reproductive system than the fungicide benomyl.

Vascular anatomy of the pig kidney glomerulus: a qualitative study of corrosion casts

Pig kidney glomerular vascular anatomy was studied by scanning electron microscopy of vascular corrosion casts. A generalized vascular architecture is presented to describe the pig kidney glomerulus based upon the observation of 3,800 vascular cast glomeruli. The relative simplicity of the pig glomerular vascular architecture has allowed the characterization of different vascular segments more completely than has been possible in other mammals. Based upon relationships to the afferent arteriole, a nomenclature and definition of primary, secondary, tertiary and anastomotic vessels is proposed for the distributing vessels comprising the glomerular tuft. The existence and formation of a large central hemispheric vessel deep within the confines of a glomerular hemisphere is micrographically documented. Micrographic evidence is presented supporting the formation of the single efferent arteriole by the merging of two central hemispheric vessels within the confines of the glomerular tuft. Failure of the merging of these two vessels may result in multiple efferent arterioles.

Perioperative education. Transforming preceptor program into perioperative elective

Perioperative educators must identify the specific learning needs of their staff members and develop and provide programs relevant to those needs. These programs must have administrative support, or they will fail. As perioperative nurses, we must go beyond preceptor programs. Educators in undergraduate programs need to include perioperative courses in their curricula. If a perioperative elective is included in basic nursing curricula, students will better be able to meet the needs of their profession and their patients. A perioperative elective in the nursing curriculum would expose students to perioperative nursing and recruit the interested ones. Students who choose not to work in the OR will at least have gained an understanding of aseptic technique and teamwork. Our first preceptor course was held in May 1986. As of this writing, 11 programs have been completed. In May 1990, we met our goal of participating in a perioperative elective, which shows that educational goals can be achieved with cooperative efforts between academic and clinical programs.

Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7

A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.

The fungicide benomyl (methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate) causes testicular dysfunction by inducing the sloughing of germ cells and occlusion of efferent ductules

Adult male Sprague-Dawley rats (100 days of age) were given single oral doses of the fungicide benomyl (methyl 1-(butylcarbamoyl)-2- benzimidazolecarbamate) in dosages ranging from 25 to 800 mg/kg body weight. The testis and excurrent ducts were examined at 2 and 70 days posttreatment to determine the chemical effects on spermatogenesis and the epididymis. Primary effects seen at 2 days postexposure were testicular swelling and occlusions of the efferent ductules. Mean testis weight peaked with 400 mg/kg. Premature release of germ cells (sloughing), detected even with the lowest dosage (25 mg/kg), was the most sensitive short-term response to benomyl. Sloughing was found primarily in Stage VII of the spermatogenic cycle at the lower dosages, but at higher dosages sloughing extended into all stages except for Stages VIII-XI. Occlusions of the efferent ductules of the testis were dose-dependent and correlated with testis weight. Sperm and sloughed germ cells were compacted in the ductal lumen of occluded ductules, which were surrounded by two to four layers of polymorphonuclear leukocytes and other inflammatory cells. Although the caput epididymidis contained sloughed germ cells and appeared swollen, evidence of permanent occlusion was not found. The long-term (70 days) effects of benomyl were decreased testis weight (at 400 mg/kg), dose-dependent increases in seminiferous tubular atrophy, and increases in the number of reproductive tracts containing occluded efferent ductules. Fibrosis, granulomas, and abnormal growth were long-term consequences of occluded ductules, which were present 100% of the time in testes containing 26-100% seminiferous tubular atrophy. Only a few testes were found to be completely regressed. Occlusion of efferent ductules and disruption of the seminiferous epithelium by sloughing of germ cells are overlapping dose-dependent mechanisms responsible for short- and long-term effects of benomyl on the rat testis.

Dual effect of serotonin on growth of bovine pulmonary artery smooth muscle cells in culture

We have previously reported that serotonin (5-hydroxytryptamine [5HT]) alters cultured bovine pulmonary artery smooth muscle cell (SMC) configuration through two different regulatory mechanisms. We now report that 5HT also regulates SMC growth through these same two mechanisms--a stimulatory event initiated intracellularly and inhibition of growth resulting from a cell surface action. 5HT (1 microM) plus 0.1 mM iproniazid (a 5HT metabolic inhibitor) produced a severalfold stimulation of DNA synthesis (as measured by [3H]thymidine incorporation) of SMCs after a 17-24-hour incubation with only a slight elevation of cellular cAMP. This stimulatory effect responded synergistically with other growth factors including platelet-derived growth factor, fibroblast growth factor, and epidermal growth factor and was effectively reversed by 5HT uptake inhibition. It was not produced by 5-hydroxyindoleacetic acid, a metabolite of 5HT. In the presence of 1 microM 5HT plus 0.1 mM isobutylmethylxanthine (IBMX), cAMP was elevated eightfold, dendritic formation occurred, and [3H]thymidine labeling of SMCs was inhibited. Inhibition of labeling by [3H]thymidine was mimicked by other agents that elevated cellular cAMP (10 microM histamine, 1 microM isoproterenol plus 0.1 mM IBMX, and 10 microM forskolin) and by 1 mM dibutyryl cAMP. This inhibitory effect was not blocked by either inhibition of 5HT uptake or 5HT-receptor antagonists ketanserin (5HT2); methiothepin, spiperone, and mianserin (5HT1/5HT2); and 3-tropanyl-indole-3-carboxylate and 3-tropanyl-3,5-dichlorobenzoate (5HT3). However, similar to 5HT, the 5HT1A agonist, (+/-)-8-hydroxy-(+/-)-2-dipropylamino-8-hydroxy-1,2,3, 4-tetrahydronaphthalenehydrobromide, in association with IBMX, produced an elevation in cAMP and inhibition of labeling by [3H]thymidine. 5HT, in the presence of either iproniazid or IBMX, did not alter [Ca2+]i, indicating that [Ca2+]i was not a signal for either of these actions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of photoperiod on body weight and food intake of obese and lean Zucker rats

Although the rat is usually not considered to be sensitive to photoperiod, under some experimental conditions photoperiod responses are unmasked. In addition, we have observed photoperiod-induced changes in body weight gain in lean and obese Zucker rats. In this experiment, body mass, food intake, body composition, brown adipose tissue (BAT) thermogenic state, and blood concentrations of corticosterone, insulin, and glucose were evaluated under one of two lighting conditions: a short (10 h light: 14 h dark) or a long (14 h light: 10 h dark) photoperiod. Plasma corticosterone and glucose concentrations measured under fasting conditions were unaffected by photoperiod in either genotype. The amount of BAT mitochondrial protein isolated was less in long photoperiod rats. BAT mitochondrial GDP binding was unaffected by photoperiod in the lean rats, but tended to be lower in long photoperiod obese rats than in short photoperiod obese rats. Although, photoperiod had no effect on daily food intake of rats exposed to the short versus long photoperiod, body mass was heaviest in obese rats raised in long photoperiod. Plasma insulin was increased in both lean and obese rats in long photoperiod. In addition, fat storage appeared to shift to internal depots in the lean rats exposed to long photoperiod. Our data demonstrate that photoperiod does have an effect on male Zucker rats with respect to body weight and fat distribution, with the obese rats being more sensitive to changes in photoperiod than the lean rats.

Fine structural characteristics and synaptic connections of trigeminocerebellar projection neurons in rat trigeminal nucleus oralis

In order to classify the presynaptic terminals contacting trigeminocerebellar projection neurons (TCPNs) in rat trigeminal nucleus oralis (Vo), electron-microscopic examination of sequential thin sections made from TCPNs located in the border zone (BZ) of Vo, labeled by the retrograde transport of horseradish peroxidase, was undertaken. The use of BZ TCPNs, labeled in Golgi-like fashion so that many of their dendrites and axons were visible, allowed for the determination of the distribution of each bouton type along the soma and dendrites, as well as for the characterization of the morphology and synaptic relations of the labeled axon and its terminals. Three types of axon terminals contacting labeled BZ TCPNs have been recognized, depending upon whether they contain primarily spherical-shaped, agranular synaptic vesicles (S endings); predominantly flattened, agranular synaptic vesicles (F endings); or a population of pleomorphic-shaped, agranular synaptic vesicles (P endings). The S endings represent the majority of axon terminals contacting labeled BZ TCPNs and establish asymmetrical axosomatic and axodendritic synaptic contacts. Many S endings are situated in one of two types of synaptic glomeruli. One type of glomerulus has a large S ending at its core, whereas the other contains a small S ending. Large-S-ending glomeruli include only labeled distal dendrites of BZ TCPNs; small-S-ending glomeruli contain either a labeled soma, proximal dendrite, or distal dendritic shaft. The remaining S endings are extraglomerular, synapsing on distal dendrites. P endings are less frequently encountered and establish intermediate axosomatic and axodendritic synapses. These endings exhibit a generalized distribution along the entire somatodendritic tree. F endings make symmetrical axodendritic synapses with distal dendrites, are only found in glomeruli containing small S endings, and are the least frequently observed ending contacting labeled BZ TCPNs. The majority of axonal endings synapsing on labeled BZ TCPNs are located along distal dendrites, with only a relatively few synapsing terminals situated on proximal dendrites and somata. The axons of labeled BZ TCPNs arise from the cell body and generally give rise to a single short collateral near their points of origin. This collateral remains unbranched and generates several boutons within BZ, while the parent axon acquires a myelin sheath and, without branching further, travels dorsolaterally toward the inferior cerebellar peduncle. The collateral boutons resemble extraglomerular S endings. They contain agranular, spherical-shaped synaptic vesicles and make asymmetrical axodendritic synapses with small-diameter unlabeled dendritic shafts in the BZ neuropil.

Maternal brown fat metabolism returns to control level by four weeks postweaning in rats

We studied body composition, white and brown adipose tissue cellularity, lipoprotein lipase activity and metabolic enzyme activity in three groups of rats: nonpregnant controls, lactating dams and nonlactating dams (i.e., dams not permitted to suckle their young). Nine to 11 rats in each group were killed on d 12 postpartum (study d 34) and on d 40 postpartum (study d 62). During lactation, brown fat citrate synthase, beta-hydroxyacylCoA dehydrogenase (HOAD) and lipoprotein lipase activities were significantly lower in the lactating than in the nonlactating dams or virgin controls. Although the nonlactating dams had their pups removed within 24 h after delivery, by d 12 postpartum citrate synthase and HOAD activities were significantly lower than those of nonpregnant controls. By the end of the study there were no differences among the three groups except in the case of HOAD. HOAD activity in the lactation group was significantly lower than in the nonlactation group. White fat cell number in the parametrial depot was significantly increased in the nonlactation groups by d 12 postpartum. In the lactation group, increased white fat cell number in this depot was detectable at d 40 postpartum, when carcass fat stores and fat cells had been repleted. These results demonstrate that both lactating and nonlactating dams undergo cellular hyperplasia, at least in the parametrial depot. This may predispose them to obesity. Also, decreased brown fat metabolism in the nonlactating dams may be contributing to their significantly greater carcass fat content at d 12 postpartum.

Diaphragm atrophy and weakness in cortisone-treated rats

Despite frequent therapeutic use, the potential of corticosteroids to produce respiratory muscle myopathy is unknown. We studied effects of chronic steroid treatment on diaphragm mass and function. Eleven Sprague-Dawley rats were treated with cortisone acetate (100 mg.kg-1.day-1 im) for 10 days. Controls (injected with vehicle) included 11 freely eating rats and 11 animals pair fed to match food intake of cortisone rats. Steroid treatment depressed body weight 30% compared with controls. Mass of diaphragm, gastrocnemius, and extensor digitorum longus showed significant atrophy (30%); heart and soleus were unaffected. Isometric contractile properties of costal diaphragm strips were studied in vitro using direct stimulation. The force-frequency relationship was markedly depressed by steroid treatment, both at low and high frequencies. However, force developed per unit cross-sectional area was similar among all three groups, as were twitch characteristics. When stimulated every minute, forces developed by control strips fell progressively, whereas the forces of cortisone-treated strips remained unchanged. When stimulated every 5 s, the fall in force was not different between groups. We conclude that cortisone weakened the diaphragm by decreasing muscle mass but made the diaphragm more resistant to one form of fatigue in vitro.

Prolactin stimulates food intake in the absence of ovarian progesterone

Increases in serum estrogen inhibit food intake. Conversely, progesterone stimulates food intake, probably via its antiestrogenic action. We have reported that elevated serum prolactin also stimulates food intake in female rats. It is unclear whether this effect is mediated through elevated levels of progesterone. The present study investigated the effects of prolactin on food intake and brown fat activity in the absence of progesterone. Female Osborne-Mendel rats were assigned to one of six groups: sham operated (Sham, n = 10), ovariectomized (OVX, n = 10), OVX + low estrogen (EL, n = 11), OVX + EL + prolactin (PIT, n = 9), OVX + high estrogen (EH, n = 10), and OVX + EH + PIT (n = 8). Estrogen levels were elevated by Silastic implants. Prolactin levels were elevated through pituitary transplants placed under the kidney capsule. Nine days postsurgery, food intake was significantly higher in OVX vs. Sham rats. Estrogen-treated rats (OVX + EL and OVX + EH) had significantly suppressed food intake values compared with both Sham and OVX animals. Finally, hyperprolactinemic rats (OVX + EL + PIT and OVX + EH + PIT) ate significantly more food than did estrogen-treated rats without pituitary explants. Despite the hyperphagia, no significant differences in brown fat GDP binding were observed. These data indicate that prolactin stimulates food intake in the absence of ovarian progesterone.

Prolactin stimulates food intake in a dose-dependent manner

Lactation in the rat is marked by pronounced hyperphagia and suppression of brown fat (BAT) thermogenic capacity. We previously examined the possibility that elevated prolactin levels mediate these changes. The present study evaluated the effect of varying prolactin levels on food intake, BAT mitochondrial GDP binding, and carcass adiposity. Female rats were injected daily for 10 days with ovine prolactin at one of three doses: high = 3.0, medium = 1.0, or low = 0.3 micrograms/g body wt. Controls were injected with 0.9% NaCl. A group of uninjected rats served as an additional control. Cumulative food intake was significantly elevated in a dose-dependent manner in the prolactin-treated animals relative to the saline-injected and uninjected controls. Compared with the saline controls, the mean cumulative food intake was greatest at the high dose (20% increase), intermediate at the medium dose (17%), and smallest at the low dose (12%). Prolactin-treated rats gained significantly more weight during the experiment than did controls. Despite the hyperphagia in the prolactin-treated rats, no significant differences in BAT mitochondrial GDP binding were observed among the five groups. These data indicate that elevated prolactin levels stimulate food intake in a dose-dependent manner and that this hyperphagia is not accompanied by an increase in BAT mitochondrial GDP binding.

Hyperprolactinemia prevents short photoperiod-induced changes in brown fat

Previous studies demonstrated that short photoperiod exposure significantly decreases circulating prolactin levels. The present study investigated the possibility that concomitant changes in brown fat tissue mass, protein content, thermogenic capacity, and carcass composition are dependent on this change in prolactin levels. Male golden (Syrian) hamsters were sham operated and exposed to a short (10L:14D) or long (14L:10D) photoperiod. A third group was implanted with exogenous pituitaries under the right kidney capsule and exposed to a short photoperiod. In experiment I, 4 wk of short- vs. long-photoperiod exposure did not result in significant changes in circulating prolactin levels, nor was there an increase in brown fat mass, protein content, or thermogenic capacity. Four weeks of short-photoperiod exposure did significantly increase carcass lipid content. However, this increase did not occur in hamsters exposed to 4 wk of short photoperiod but made hyperprolactinemic (implanted with two exogenous pituitaries). Ten weeks of short photoperiod significantly reduced circulating prolactin levels. Concomitantly, brown fat mass, protein content, and thermogenic capacity, as well as carcass fat, were increased. These short-photoperiod-induced changes were not observed in similarly exposed hamsters that were made hyperprolactinemic via two implanted pituitaries. In experiment II, similar changes in brown fat and body composition occurred in sham-operated hamsters exposed to 10 wk of short photoperiod. These changes were prevented in hamsters exposed to 10 wk of short photoperiod but made hyperprolactinemic via only one implanted pituitary. These results suggest that decreased prolactin is a necessary condition for the increased brown fat mass, protein content, and thermogenic capacity that occurs when golden hamsters are exposed to short photoperiod.

Growth of juvenile white sturgeon (Acipenser transmontanus) fed different purified diets

Two experiments were conducted to develop a purified diet suitable for studying nutritional requirements of juvenile white sturgeon (Acipenser transmontanus). In the first experiment, growth and survival rates of fish fed a purified diet (SPD) containing 50% casein:wheat gluten:egg white (6.2:3.0:0.8) and 8% refined soy lecithin were significantly (P less than 0.05) better than those fed a commercial nonpurified rainbow trout diet, a purified rainbow trout diet containing 50% casein:gelatin (7:3) or a purified catfish diet containing 34% spray-dried egg white. In the second experiment, fish fed SPD diet with or without cholesterol but with the same amount of lipid grew equally well. Fish fed SPD diet with lecithin grew significantly better than those fed SPD diet with its 8% lecithin replaced with an equal amount of an oil mixture. In both experiments, fish with good growth and survival rates also had significantly lower body moisture and higher protein and lipid contents than fish with poor growth and survival rates. Results suggest that the SPD diet with lecithin and without cholesterol (SPD-C) is a suitable purified diet for juvenile white sturgeon.

The cafeteria diet--an inappropriate tool for studies of thermogenesis

Diet-induced thermogenesis (DIT) is defined as a regulatory, facultative component of energy expenditure, stimulated by overeating, which helps maintain energy balance. DIT may play a central role in the regulation of energy expenditure and in the etiology of certain types of obesity. Most experiments testing the existence or the mechanisms of DIT have used the cafeteria diet for the purposes of stimulating hyperphagia, a requisite for studies of DIT. Yet such a diet is inappropriate for studies of thermogenesis because its use prevents researchers from obtaining an experimental outcome that can be clearly interpreted. The primary limitation of the cafeteria diet is that its nutritional composition is uncontrolled. The diet is self-selected from a variety of supermarket foods that tend to be high in fat and/or carbohydrate and low in protein, vitamins and minerals. Hence, the diets consumed by the animals are likely to be deficient in protein, vitamins or minerals. There is evidence that dietary deficiency of protein, vitamins and minerals can increase thermogenesis and in protein-adequate diets, the balance of fat and carbohydrate in the diet can also influence thermogenesis with high carbohydrate diets increasing thermogenesis more than isoenergetic high fat diets. Hence, an observed increase in thermogenesis in cafeteria fed animals might be interpreted incorrectly to be the result of increased energy consumption when it is attributable to dietary imbalance or deficiency. Because the diet is self-selected, it is possible for each animal to choose a diet that varies in nutritional composition from that selected by every other animal, so control of dietary intake is compromised.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism at thermoneutrality and in the cold is reduced in the neonatal preobese Zucker fatty (fa/fa) rat

Minimum and maximum rates of oxygen consumption (VO2) were determined in 2-, 6- and 8-d-old lean (Fa/?) and preobese (fa/fa or "fatty") Zucker rats. On each study day, three or four naive littermate male pups were placed in individual respiration chambers submerged in a water bath and studied simultaneously over a range of ambient temperatures (24-35 degrees C). The purpose of the cold exposure was to elicit maximal oxygen consumption and to determine the ability of the rat to maintain body temperature during cold stress. Minimum rates of oxygen consumption were observed at 33-34 degrees C in both groups. As ambient temperature was reduced, VO2 increased and rectal temperature decreased. Regression analysis revealed a significantly reduced oxygen consumption in the preobese pups within the thermoneutral zone and during cold exposure. A defect in energy expenditure for heat production was evident in the preobese (fa/fa) pups as indicated by their attenuated cold-induced rate of oxygen consumption and decreased ability to maintain body temperature during cold stress relative to their lean (Fa/?) littermates. Their lower VO2 within the thermoneutral zone implies that the preobese (fa/fa) pups have a decreased metabolic rate even under conditions in which cold-induced thermogenic mechanisms are turned off.

Automated cognitive assessment of elderly patients: a comparison of two types of response device

Groups of 14 cognitively impaired elderly people were tested on two automated cognitive tests on several occasions. Patients registered their responses using either a touch-sensitive screen or a board with illuminated response buttons. The results indicate that the touch-sensitive screen is probably a more suitable response device than the button-board. Suggestions that it would prove disadvantageous to elderly patients were not supported, and its continued use is recommended.

Decreased testosterone levels do not mediate short-photoperiod-induced brown fat changes

Previous studies showed that short photoperiod increased brown fat (BAT) mass and reduced gonadal size and gonadal hormone secretion in hamsters. The present study investigated the possibility that the effects on BAT were dependent on reduced levels of gonadal hormones. BAT from male Syrian hamsters exposed to short photoperiod for 10 wk was significantly greater in mass, protein content, and total maximal citrate synthase and beta-hydroxyacyl-CoA dehydrogenase activities than was BAT from long-photoperiod hamsters, These differences between short- and long-photoperiod exposure were observed in hamsters housed at 21 as well as at 8 degrees C. Short photoperiod also increased the total recovered mitochondrial GDP binding, a finding consistent with increased BAT thermogenic capacity. These short-photoperiod effects were neither mimicked by castration of long-photoperiod hamsters nor prevented by high levels of testosterone administered to short-photoperiod animals. Castration did attenuate the effects of short photoperiod on BAT growth if, after surgery and prior to short-photoperiod exposure, the animals were housed at a long photoperiod for 2-3 wk. In contrast, in hamsters immediately placed at short photoperiod after surgery, castration did not inhibit short-photoperiod effects. The present three experiments demonstrate that, in addition to increasing BAT mass, short photoperiod elevates the thermogenic capacity of BAT, and this elevation does not require the absence or a much reduced testosterone level.

Hyperprolactinemia stimulates food intake in the female rat

Lactation in the rat is marked by extreme hyperphagia. The present study examined the possibility that elevated prolactin levels contribute to this increase. It also evaluated the effects of hyperprolactinemia on brown adipose tissue and carcass composition. Virgin Osborne-Mendel rats were made hyperprolactinemic via ectopic pituitary transplants (PIT, n = 9) or were sham-operated (SHAM, n = 8). Eight lactating rats (LACT) served as additional controls. Food intake, body weight and rectal temperature were recorded daily. Eleven days postsurgery (or 11-12 days postpartum), the rats were sacrificed, and brown fat (scapular, axillary, cervical and thoracic) was excised, weighed, and assayed for GDP binding, one indicator of thermogenic capacity. Carcasses were subjected to body composition analysis. Although prior to surgery, PIT and SHAM rats weighed the same, PIT rats gained significantly more weight during the experiment than did SHAMs. Percent body fat and food intake (both total intake and intake relative to metabolic body size) were significantly elevated in the PIT rats. GDP binding in both PIT and LACT rats was significantly less than in SHAMs. This was true whether GDP binding was expressed per mg mitochondrial protein or per total amount of mitochondrial protein recovered. These data confirm that brown fat thermogenic capacity is suppressed during lactation. They also demonstrate that elevations of serum prolactin, to levels that are well within physiological limits, are capable of stimulating food intake and white fat deposition in the female rat. It is presently unclear whether these results are a direct or an indirect effect of hyperprolactinemia.

Brown fat mediates increased energy expenditure of cold-exposed overfed neonatal rats

Genetically lean rat pups, overfed by being raised in small litters of three from day 1 postpartum, rapidly become obese compared with pups raised in standard sized litters of eight. Because of the rapid onset of their obesity, we expected that overfed pups would exhibit defective brown fat thermogenesis as is seen in neonatal genetically obese rodents. O2 consumption (VO2) was measured in 2-, 4-, 6-, and 8-day-old homozygous lean (Fa/Fa) Zucker pups from each treatment. We determined minimum rate of VO2 at thermoneutrality and maximum VO2 in response to progressively colder ambient temperatures. Overfed pups were fatter than standard-fed pups (P less than 0.001). But contrary to our prediction, overfed pups had a significantly increased maximum VO2 in response to acute cold exposure. To test the hypothesis that brown fat mediated the increased VO2 in the overfed pups, scapular brown fat lipectomies were performed on a new group of overfed pups at 2 days of age and compared with sham-operated littermate controls. On day 8, no differences in minimum VO2 were seen at thermoneutrality when brown fat is turned off. But maximum VO2 in response to cold, when brown fat is turned on maximally, was significantly reduced in the lipectomized overfed pups compared with sham-operated overfed littermates. These data suggest that manipulations of diet, accomplished by raising pups in small litters, can increase brown fat thermogenic function. The results of the lipectomy experiment imply that brown adipose tissue is a primary mediator of the increased energy expenditure in response to acute cold exposure in the overfed pups.

Energy expenditure is reduced in preobese 2-day Zucker fa/fa rats

The rate of oxygen consumption was measured in 2-day Zucker preobese (fa/fa), homozygous (Fa/Fa) lean, and lean rats of unknown genotype (Fa/?) over the ambient temperature range of 26-35 degrees C. Significant differences in body mass were found among the three groups at this early age, the preobese pups having the greatest body mass. To account for body mass differences, the oxygen consumption data were expressed in terms of metabolic body size (ml O2 consumed X g body mass-2/3 X h-1). This mass-independent rate of oxygen consumption was significantly lower in the preobese pups than in the homozygous lean (Fa/Fa) pups at both thermoneutral (33-34 degrees C) and cold (26-27 degrees C) ambient temperatures at which, respectively, minimal and maximal rates of oxygen consumption were observed. This reduction in energy expenditure occurs before the establishment of hyperphagia or decreased levels of activity in the preobese pups. These data support the view that attenuated energy expenditure is a significant contributor to the early development of obesity in the Zucker fatty rat and point to the possibility of defective brown adipose tissue-mediated thermogenesis in the preobese pup.

Brown fat thermogenesis and its role in the development of obesity

The role of brown fat thermogenesis in the development of obesity is considered from a number of perspectives. In adult rats, the impact of scapular brown fat lipectomy on carcass fat accretion was examined in three different rodent models: the Zucker lean (Fa/-) rat which is relatively resistant to obesity, the Zucker obese (fa/fa) rat which is characterized by a particularly severe form of hyperplastic obesity and the Osborne Mendel rat which remains lean on a standard pelleted diet but readily becomes obese on a palatable high fat diet. The consequences of brown fat lipectomy varied from no effect on carcass white fat accretion in Zucker Fa/- lean rats to a significant increase in adiposity in the Zucker fatty fa/fa relative to their respective sham-operated controls. The effect of the Osborne Mendel rat was intermediate between the Fa/- and the fa/fa. The results point to the importance of genetic background with respect to the impact of brown fat lipectomy on the development of white fat adiposity. In the developing Zucker rat at 2 and 8 days of age, in vivo evidence is presented to support the concept that brown fat thermogenesis is attenuated in the fatty fa/fa preobese pup. In animals of the fatty fa/fa genotype, maximum oxygen consumption in response to acute cold exposure was lower than in lean pups of the Fa/Fa genotype. Moreover, at 8 days of age, the rectal temperature of the cold-exposed fa/fa pups fell more precipitously than did that of the lean during the period of cold exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Brown adipose tissue lipectomy leads to increased fat deposition in Osborne-Mendel rats

Inter- and subscapular brown adipose tissue depots were removed from nine female Osborne-Mendel rats. These lipectomized animals and nine sham-operated controls recovered from surgery for 7 days at 25 degrees C and were then placed on a highly palatable liquid diet. All animals were maintained for a 2nd wk at 25 degrees C before being switched to 8 degrees C. After 9 wk in the cold, animals were killed, and the brown adipose tissue was dissected from scapular, cervical, thoracic, perirenal, and axillary regions. Total brown fat pad mass, protein content, brown adipocyte number, citrate synthase activity, and beta-hydroxyacyl CoA dehydrogenase activity in each of the dissected brown fat depots were significantly less than those of the sham-operated controls. Thus there was incomplete metabolic compensation in the remaining brown fat depots after the removal of the scapular brown fat in the lipectomized rats. The mass and lipid content of the retroperitoneal white adipose depot were significantly increased in the lipectomized rats as was their carcass fat content (up 14%). Food intake of the lipectomized rats was slightly but significantly decreased. These data indicate that a reduction in the amount of functional brown fat is accompanied by increased body fat accretion and are thus consistent with the hypothesis that decreased brown adipose thermogenesis can lead to altered energy balance and increased white fat deposition.

The effect of brown fat removal on the development of obesity in Zucker and Osborne-Mendel rats

Removal of significant amounts of brown fat in young Zucker rats maintained at room temperature triggered compensatory changes in the remaining brown fat depots. These changes, which occurred to a greater extent in the lean than in the obese rats, enhanced the thermogenic potential of the remaining depots, thus possibly accounting for the lack of increased adiposity in these lipectomized rats. When the Zucker rats were maintained in the cold, rather than at room temperature, their ability to compensate for removal of the scapular brown fat was compromised, particularly in the obese animals. Under such conditions, the amount of functional brown fat was significantly reduced, and the amount of body fat elevated. In the lipectomized Zucker rats, this increase in adiposity was accompanied by increased body mass. In contrast, in the cold-exposed Osborne-Mendel rats, where lipectomy was not accompanied by compensatory increases in the mass and cellularity of the remaining brown fat depots, increased body fat occurred in the absence of any increase in food intake or in total body mass.