Cortex Biopsies Research Articles

The cerebroprotective effects of pentoxifylline and aprotinin during cardiopulmonary bypass in dogs.

The purpose of this study was to investigate the cerebroprotective effects of pentoxifylline (PNX) and aprotinin in dogs using cardiopulmonary bypass (CPB). Eighteen clinically healthy dogs were divided into three groups: Group 1 (control, n = 6), Group 2 (PNX, n = 6), and Group 3 (aprotinin, n = 6). PNX was administered at a dose of 300 mg/day in Group 2 three days before the operation and during the operation. Half a million IU aprotinin were added to the prime solution and 500,000 IU were transfused via a central venous jugular catheter preoperatively in Group 3. Blood samples were taken from the central jugular vein before and after CPB and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and S100beta protein were measured. Gliosis was investigated histopathologically in cerebral cortex biopsy samples under light microscopy. The preoperative results of IL-6, TNF-alpha, and S100beta protein values were found to be significantly higher (p < 0.001) when compared with postoperative values. This significant difference was observed in the same parameters between Groups 1 and 2, and 1 and 3 (p < 0.001). There was no significant difference between Groups 2 and 3. Comparison between pre- and postoperative levels of IL-6 and TNF-alpha for Group 2 and Group 3 revealed statistically significant differences (p < 0.001), whereas S100beta protein levels did not. Histopathological examinations showed significant differences between the control group and PNX and aprotinin, and between aprotinin and PNX groups (p < 0.001). PNX and aprotinin might be useful in order to reduce postoperative cerebral damage in patients undergoing cardiac surgery with CPB.

Impaired expression of the cell cycle regulator BTG2 is common in clear cell renal cell carcinoma.

The prognosis of patients with renal cell carcinoma (RCC) is poor. A full understanding of the molecular genetics and signaling pathways involved in renal cancer development and in the metastatic process is of central importance for developing innovative and novel treatment options. In this study, BD Atlas Human Cancer 1.2 cDNA microarrays were used to identify genes involved in renal tumorigenesis. By analyzing gene expression patterns of four clear cell RCC (cRCC) cell lines and normal renal tissue, 25 genes were found differentially expressed. To determine the relevance of these genes, RNA in situ hybridization was performed on a tissue microarray generated from 61 snap-frozen primary renal cell carcinomas and 12 normal renal cortex biopsies. B-cell translocation gene 2 (BTG2), a negative cell cycle regulator, which was expressed in normal renal tissue but down-regulated in cRCC cell lines and primary cRCCs, was selected for additional experiments. Quantitative BTG2 mRNA expression analysis in 42 primary cRCCs and 18 normal renal cortex biopsies revealed up to 44-fold reduced expression in the tumor tissues. Decrease of BTG2 expression was not associated with tumor stage, grade, and survival. Cell culture experiments demonstrated that BTG2 expression was weakly inducible by the phorbolester 12-O-tetradecanoylphorbol-13-acetate in one of four cRCC cell lines. In contrast, increasing cell density led to elevated BTG2 mRNA expression in three of four cRCC cell lines. In both experiments, BTG2 mRNA levels did not reach values observed in normal renal tissue. These data suggest that down-regulation of BTG2 is an important step in renal cancer development.

Morphometry of E-PTA stained synapses at the periphery of pathological lesions

We carried out a novel application of the disector sampling and counting method, in a biopsy material from the pathologic human brain, to estimate the synaptic structural dynamics, quantitatively. Parietal cortex biopsies of adult (mean age: 40.0 years) and old (mean age: 66.2 years) patients having undergone surgical intervention were investigated. The tissue samples were excised at the periphery of meningioma masses. Synaptic contact zones were stained en bloc by the ethanol phosphotungstic acid (E-PTA) preferential technique which selectively enhances both the pre- and post-synaptic paramembranous material separated by a sharp cleft against a very faint background, thus facilitating and objectifying synaptic morphometry. The disector method, associated with currently used morphometric formulas, enabled us to measure the number of synapses/μm3 of tissue (numeric density: Nv); the total area of the synaptic contact zones/μm3 of tissue (surface density: Sv) and the average synaptic size (S). In old vs. adult patients, Nv decreased by 7.5% (Mean (SEM): Adult 2.0040(0.0452); Old 1.6780(0.0623)), while S increased by 17.5% (Adult 0.0203(0.0026); Old 0.0246(0.0035)). Sv did not show any age-related difference. The same negative correlation between Nv and S has also been reported in physiological aging, and this suggests the active presence of age-related synaptic restructuring mechanisms in the nervous tissue surrounding a tumoral mass.

Coordination of Fibroblast Growth Factor Receptor 1 (FGFR1) and Fibroblast Growth Factor-2 (FGF-2) Trafficking to Nuclei of Reactive Astrocytes around Cerebral Lesions in Adult Rats

Traumatic injury to the adult central nervous system initiates a cascade of cellular and trophic events, culminating in the formation of a reactive gliotic scar through which transected axons fail to regenerate. Levels of fibroblast growth factor-2 (FGF-2), a potent gliogenic and neurotrophic factor, together with its full-length receptor, FGF receptor 1 (FGFR1) are coordinately and significantly increased postinjury in both nuclear and cytoplasmic fractions of extracted cerebral cortex biopsies after a penetrant injury. FGFR1 is colocalized with FGF-2 in the nuclei of reactive astrocytes, and here FGF-2 is associated with nuclear euchromatin. This study unequivocally demonstrates coordinate up-regulation and trafficking of FGF-2 and full-length FGFR1 to the nucleus of reactive astrocytes in an in vivo model of brain injury, thereby implicating a role in nuclear activity for these molecules. However, the precise contribution of nuclear FGF-2/FGFR1 to the pathophysiological response of astrocytes after injury is undetermined.

Determination of Follicle Numbers in Human Ovarian Biopsies—A Method for Estimation of Outcome of Ovarian Cryopreservation?

Objectives: Cryopreservation of human ovarian cortex as a strategy for preserving fertility has recently been object to numerous investigations. However there is only few data on the number of follicles necessary for effective therapy, as well as data concerning the number of follicles available in ovarian cortex biopsies mostly bases on estimations. The objectives of this study were: (1) to determine follicular density in ovarian cortex samples using a calculation basing on follicular counts from serial sections, (2) to assess if the distribution pattern of follicles over the ovarian cortex allowed prediction of follicular density from the determination of follicular contents in neighbouring samples.

Electron microsocopy of brain amyloid plaques from a patient with new variant Creutzfeldt-Jakob disease.

Cerebral cortex biopsy from a patient with new variant Creutzfeldt-Jakob disease (nvCJD) has been examined at the electron microscope level. Spongiform changes corresponded mostly to distended neurites scattered in the neuropil or surrounding amyloid plaques. These latter exhibited heterogeneous submicroscopic morphology including variable amount of loosely interwoven amyloid fibrils admixed in a cellular-rich environment constituted essentially by abnormal neuronal processes. By immunoelectron microscopy, fibrils and some membrane structures reacted with anti-prion protein (PrP) antibodies. One striking aspect was the presence of many small dystrophic neurites without paired helical filaments. Moreover, amyloid fibrils showed unexpected intimate association with abnormal membranes, suggesting a relationship between PrP fibrillogenesis and membrane alteration. These ultrastructural findings provide an additional criterion to distinguish nvCJD-from sporadic CJD-type plaques and reinforce the hypothesis that nvCJD brain is infected by a distinctive strain of the transmissible agent encephalopathy.

Efficacy of Succimer Chelation for Reducing Brain Lead in a Primate Model of Human Lead Exposure

The extent to which succimer (meso-2,3-dimercaptosuccinic acid [DMSA], Chemet) reduces brain lead (Pb) levels may be a primary consideration in evaluating its efficacy for reducing neurotoxicity. Clinical research in this area has been hampered by the need to use blood Pb levels as the index of treatment efficacy, despite the fact that brain Pb level is the exposure parameter of greater relevance to cognitive outcomes. Here, a nonhuman primate model of human Pb exposure was used to determine: (1) The efficacy of oral succimer for reducing brain Pb derived from chronic or recent exposures, and (2) The extent to which blood Pb levels reflect brain Pb prior to and following chelation. Adult rhesus monkeys were chronically exposed to Pb orally for 5 weeks to reach and maintain a target blood Pb level of 35–40 μg/dL. Chelation of Pb from recent exposures was assessed using a stable 204Pb isotope tracer administered over 4 days prior to treatment. Immediately prior to chelation, a prefrontal cortex (PFC) biopsy was collected to determine pretreatment brain Pb levels. Subsequently, monkeys were assigned to vehicle (n = 5) or succimer (n = 6, 30 mg/kg/day × 5 days followed by 20 mg/kg/day × 14 days) groups. Blood and brain PFC, frontal lobe (FL), hippocampus (H), and striatum (S) were analyzed for total Pb and 204Pb tracer concentrations by magnetic sector inductively coupled plasma–mass spectrometry. There were no measurable differences in brain Pb concentrations between the succimer and vehicle groups, indicating that succimer treatment was not efficacious in reducing brain Pb levels. In contrast, the cessation of Pb exposure significantly reduced brain (PFC) Pb (≈34%) when compared to pretreatment levels (succimer and vehicle groups). Pb concentrations also varied among brain regions (PFC > FL ≈ H > S). Finally, pretreatment PFC Pb concentrations were significantly correlated with the integrated blood Pb level (AUC) over the Pb exposure period, but not with the single pretreatment blood Pb collected concurrently with the PFC biopsy. Following treatment, blood Pb levels correlated only with Pb in the PFC, and not the other brain regions measured (FL, H, S). These data indicate that, under the conditions of this study, succimer treatment did not reduce brain Pb levels beyond the cessation of Pb exposure alone. Moreover, a single blood Pb measurement may be a poor predictor of brain Pb levels, reflecting limitations in the use of blood Pb level as an indicator of treatment efficacy.

Cadmium, mercury, and lead in kidney cortex of the general Swedish population: a study of biopsies from living kidney donors.

Cadmium, mercury, and lead concentrations were determined in deep-frozen kidney cortex biopsies taken from 36 living, healthy Swedish kidney donors (18 males and 18 females), who were 30-71 (mean 53) years of age. Information about occupation, smoking, the presence of dental amalgam, and fish consumption could be obtained for 27 of the donors. The samples (median dry weight 0.74 mg) were analyzed using inductively coupled plasma mass spectrometry, and the results were transformed to wet-weight concentrations. The median kidney Cd was 17 micrograms/g (95% confidence interval, 14-23 micrograms/g), which was similar in males and females. In 10 active smokers, the median kidney Cd was 24 micrograms/g, and in 12 who never smoked, it was 17 micrograms/g. The median kidney Hg was 0.29 micrograms/g, with higher levels in females (median 0.54 micrograms/g) than in males (median 0.16 micrograms/g). Subjects with amalgam fillings had higher kidney Hg (median 0.47 micrograms/g, n = 20) than those without dental amalgam (median 0.15 micrograms;g/g, n = 6), but kidney Hg was below the detection limit in some samples. Nearly half of the samples had kidney Pb below the detection limit. The median kidney Pb was estimated as 0. 14 micrograms/g. This is the first study of heavy metals in kidney cortex of living, healthy subjects, and the results are relatively similar to those of a few previous autopsy studies, indicating that results from autopsy cases are not seriously biased in relation to kidney metal concentrations in the general population. Cd concentrations in those who never smoked were relatively high, indicating considerable Cd intake from the diet in Sweden. The effect of dental amalgam on kidney Hg was as expected, although the reason for the difference in Hg levels between males and females is unclear.

Effects of follicle-stimulating hormone and serum substitution on the in-vitro growth of human ovarian follicles.

In-vitro maturation (IVM) of human ovarian follicles and oocytes could benefit infertile women, and allow the development of in-vitro systems for the study of human follicular development. Little is known about the initiation of growth of primordial follicles and the regulation of early folliculogenesis. An ovarian tissue-slice culture system was used to examine the effects of media composition, follicle stimulating hormone (FSH) and serum substitution on the development of small human follicles in vitro. Human ovarian cortex biopsies were cut into small pieces and cultured for 5, 10 or 15 days. Control (non-cultured) and cultured tissue was fixed, serially sectioned, and stained. The follicles contained within the tissue pieces were counted, measured, and assessed for stage of development and viability. Comparison of the ability of alpha-minimum essential medium (alpha-MEM), Waymouth's, or Earle's balanced salt solution (EBSS) culture media (all with 10% human serum) to support follicle growth demonstrated significantly increased initiation and growth of follicles in alpha-MEM during the first 10 days of culture. The supplementation of alpha-MEM with 300 mIU/ml FSH significantly reduced levels of atresia and increased the mean diameter of healthy follicles. Follicles in tissue cultured for 10 days with human serum albumin and ITS (insulin/transferrin/selenium mix) were significantly larger, more developed and showed significantly less atresia than those cultured with serum alone. Primordial to small preantral follicles can be grown under serum-substituted conditions in tissue-slice culture, and are responsive to FSH, which is thought to be acting mainly as a survival factor at these early stages.

Reduced cadmium levels in human kidney cortex in sweden.

Environmental pollution with the nephrotoxic metal cadmium is considered a potential health risk for the general population. In 1976 it was reported that the cadmium concentration in human kidney cortex in Sweden had increased in parallel with increasing levels in soil and grain during the twentieth century. Since the cadmium concentration in farming lands is still increasing, the present study was undertaken to further elucidate whether the cadmium concentration in the kidney is still increasing. Kidney cortex biopsies were collected at 171 autopsies of victims to sudden and accidental death during 1995 and 1996, and the cadmium concentrations were determined and compared with previously published Swedish data obtained from forensic autopsies. The geometric mean cadmium concentration in kidney cortex in subjects 40 years of age and younger was about 40% of the concentration found in the 1970s, while the reduction was less pronounced among older people. The highest individual concentration of cadmium was 41.5 microg/g wet weight (ww). The geometric mean concentration was less than 14 microg/g ww at ages around 50 years of age, when the cadmium concentration in kidney cortex is highest, as compared with approximately 20 microg/g ww in the 1970s. There was also a reduction in cadmium concentrations among nonsmokers; thus, a decrease in tobacco smoking in Sweden during the last decades is not the only explanation for the reduction of cadmium in the kidney cortex. Other reasons for this reduction could be changes in dietary habits and reduced cadmium contamination from Swedish industries.

Quantification of mRNA levels of endothelin receptor subtypes and preproEndothelin-1 in renal needle biopsies by competitive reverse transcriptase polymerase chain reaction

The vasoconstrictive peptide endothelin-1 (ET-1) is an autocrine/paracrine peptide of putative pathophysiological importance in renal transplant medicine. The aim of the present study was to develop a method for analysis of gene expression of the renal endothelin system in humans. Only small amounts of tissue are available from renal cortical needle biopsies. Thus, in the present study we developed a quantitative assay based on the competitive reverse transcriptase polymerase chain reaction (RT-PCR) technology. We quantified endothelin A (ET(A)) and B (ET(B)) receptor subtype mRNAs and preproET-1 mRNA levels in renal cortex biopsies obtained before nephrectomy of healthy kidney donors. Mean (+/- SEM) mRNA levels of the ET(A) and ET(B) receptor subtypes in 26 living donors were 212 +/- 23 and 368 +/- 56 amol/microg total RNA, respectively. The preproET-1 mRNA level in 19 living donors was 213 +/- 28 amol/microg total RNA. The inter-assay coefficient of variation (CV) for the assay was 10%; the intra-assay CV was 6-13%. The competitive RT-PCR assay described provides an accurate tool for gene expression investigation of the human endothelin system in renal cortical needle biopsies.

Paired helical filament morphology varies with intracellular location in Alzheimer's disease brain

Paired helical filaments (PHFs) are one of the hallmark pathologies of Alzheimer's disease (AD). PHFs occur in three intracellular locations, although hitherto, it was not known whether all PHFs are structurally homogeneous. Parietal cortex biopsies were taken from five patients with a clinical and histopathological diagnosis of AD and processed for electron microscopy. Photomicrographs were then taken of PHFs in neurofibrillary tangles (NFTs), neuropil threads (NTs) and neuritic plaque (NP) neurites and their dimensions measured. The mean half period, maximum and minimum widths of PHFs in NFTs were significantly smaller than those in NTs or NP neurites. The mean half period and maximum width of PHFs in NTs were similar to those in NP neurites. These results reveal the presence of two distinct PHF populations and investigation of their relationship may shed light on the pathogenesis of AD.

Endothelin-1 and Its Receptors A and B in Human Aldosterone-Producing Adenomas

Endothelin-1 stimulates aldosterone secretion by interacting with specific receptors. Accordingly, we wished to investigate endothelin-1, endothelin-A (ETA) receptor, and endothelin-B (ETB) receptor gene expression, localization, and properties in aldosterone-producing adenomas and in the normal human adrenal cortex. We carried out 125I-endothelin-1 displacement studies with cold endothelin-1, endothelin-3, the specific ETA antagonist BQ-123, and the specific ETB weak agonist sarafotoxin 6 C and coanalyzed data with the nonlinear iterative curve-fitting program LIGAND. We also studied gene expression with reverse transcription-polymerase chain reaction with specific primers for endothelin-1, ETA, and ETB complementary DNA. Normal adrenal cortices from consenting kidney cancer patients (n = 2) and aldosterone-producing adenomas (n = 4) were studied; for the latter, surrounding normal cortex and kidney biopsy tissue served as controls. To further localize the receptor subtypes, tissue sections were studied by autoradiography in the presence and absence of 500 nmol/L BQ-123, 100 nmol/L sarafotoxin 6 C, and 1 mumol/L cold endothelin-1. In all tissues examined, endothelin-1, ETA, and ETB messenger RNAs were easily detected. However, in aldosterone-producing adenomas, both receptors' genes were expressed at a higher level than in the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Noradrenergic modulation of γ-aminobutyric acid outflow from the human cerebral cortex

The noradrenergic modulation of endogenous γ-aminobutyric acid (GABA) outflow from slices and synaptosomes prepared from human cerebral cortex biopsies has been studied. GABA outflow was responsive to depolarizing stimuli such as ouabain and high potassium. Basal GABA outflow in slices, but not in synaptosomes, appeared to be largely dependent upon neuronal activity, being prevented by tetrodotoxin (TTX). 10 mM K +-evoked outflow in synaptosomes also proved to be TTX sensitive. Norepinephrine (NE) concentration dependently increased basal GABA outflow both in slices and synaptosomes. This effect wasα 1-adrenoreceptor-mediated because it was prevented by a selective antagonist of theα 1-adrenoreceptor class (prazosin) but not by theα 1 antagonist idazoxan. However, andα 1-mediated inhibitory modulation was also present in the preparations used, since (1) in slices, NE significantly inhibited GABA outflow in the presence of prazosin; (2) in synaptosomes, NE significantly inhibited 10 mM K +-evoked outflow in the presence of prazosin. Both of these effects were prevented by idazoxan. No β-adrenoreceptor modulation could be demonstrated. A comparison between species was also conducted. The response to ouabain and to TTX proved similar in human, rat and guinea-pig cerebral cortex. In the most simple tissue preparation used (synaptosomes), a close similarity between the three species could be observed. In all species, NE stimulated basal GABA outflow, an effect prevented by prazosin. This suggests a predominantα 1-adrenoreceptor-mediated stimulatory effect. In a more complex preparation (slices), differences between species could be demonstrated. First, in absolute values basal GABA outflow was higher in the rat compared to the human and the guinea-pig cortex. Second, although NE stimulated GABA outflow viaα 1-adrenoreceptors in all species, it wa more potent in the rat. Third, in the presence of prazosin NE significantly inhibited basal GABA outflow in the human cortex, but not in the other species. This suggests that the representation of functionalα 2-adrenoreceptors (on the cell bodies of GABA neurones and /or other connected neuronal populations) is greater in the human when compared to the rat and the guinea-pig cerebral cortex.

Erythrocyte band 3-like protein immunoreactivity in the human brain cortex.

The immunoreactivity of erythrocyte band 3 (B3-IR)-related protein was estimated on cortex biopsies from the brains of 33 patients varying in age from 14-week-old fetus until 67 years of life. B3-IR was not a feature of embryonic brains. A positive reaction was restricted to neurons. It appeared at early postnatal life, increased sharply until 9 years, and than stayed approximately stable between 17 and 67 years of age. The results indicate that there is a positive relation between the amount of neuronal band 3-like protein and the stage of human brain development.

Inhibition of Acetylcholinesterase Activity in Human Brain Tissue and Erythrocytes by Galanthamine, Physostigmine and Tacrine

Galanthamine, physostigmine and 9-amino-1,2,3,4-tetrahydroacridine (tacrine) were evaluated as inhibitors of human acetylcholinesterase activity from samples of postmortem human brain, fresh brain cortex biopsies and human erythrocytes. Acetylcholinesterase activity was most effectively inhibited in all tissues by physostigmine, followed by tacrine and galanthamine. The respective inhibitor concentrations exerting a half maximal effect (IC50) on acetylcholinesterase in postmortem human brain frontal cortex were 14 nmol/l, 1.0 mumol/l and 3.2 mumol/l versus 15 nmol/l, 1.1 mumol/l and 2.8 mumol/l in the hippocampus region. In addition, the inhibition of acetylcholinesterase by galanthamine was similar in postmortem brain and brain cortical biopsies from patients submitted to brain-tumour removal, indicating that postmortem changes up to 28 h after death probably did not influence the measurement of acetylcholinesterase inhibition. While physostigmine and tacrine acted equally on acetylcholinesterase from different sources, galanthamine was 10-fold less potent in inhibiting the enzyme activity from human brain that from human erythrocytes. Comparison with issues from mice revealed that galanthamine was selectively more potent in suppressing acetylcholinesterase in human erythrocytes. The results are discussed in the light of pharmacokinetic data, and conclusions are drawn for further clinical studies.

Synapse loss in frontal cortex biopsies in Alzheimer's disease: Correlation with cognitive severity

Ultrastructural studies of biopsied cortical tissue from the right frontal lobe of 8 patients with mild to moderate Alzheimer's disease (AD) revealed that the number of synapses in lamina III of Brodmann's area 9 was significantly decreased when compared with the number in age-matched control brains (n = 9; postmortem time, less than 13 hours). Further decline in synaptic number was seen in age-matched autopsied AD specimens. In the AD brains there was significant enlargement of the mean apposition length, which correlated with degree of synapse loss; as synapse density declined, synapse size increased. The enlargement of synapses, coupled with the decrease in synaptic number, allowed the total synaptic contact area per unit volume to remain stable in the patients who underwent biopsy. In autopsied subjects who had AD, there was no further enlargement of mean synaptic contact area. There was a significant correlation between synapse counts and scores on the Mini-Mental State examination in the patients who underwent biopsy. Lower mental status scores were associated with greater loss of synapses. Choline acetyltransferase activity was significantly decreased in the biopsied group and declined further in the autopsied specimens of AD. There was no relationship between choline acetyltransferase activity and scores on the Mini-Mental State examination or synapse number. There is evidence of neural plasticity in the AD neuropil; synaptic contact size increased in patients who had biopsy and possibly compensated for the numerical loss of synapses. But by end stage of the disease, the ability of the cortex to compensate was exceeded and both synapse number and synaptic contact area declined.(ABSTRACT TRUNCATED AT 250 WORDS)

Fine structural features of the cerebral microvasculature in hydrocephalic human infants: correlated clinical observations.

Four of 30 human cerebral cortex biopsies from infants ranging from four days to about ten years treated for hydrocephalus by shunt operations are described paying special attention to the vascular structures. The biopsy specimens were studied in semi-thin and ultrathin sections. Attention is drawn to the role of pinocytotic vesicles found in capillaries and smaller vessels as a possible transcellular route for the hydrocephalic oedema resolution. No intercellular dehiscences or the so called blisters were observed. With the passage of time, the number of membrane bound vesicles increased and arrays of pinocytotic vesicles were discernible both on the abluminal as well as luminal aspect of the capillary wall. Additionally, larger vacuoles containing electron-dense material, apparently undergoing autolysis, were also detected. The basal lamina was of uneven thickness and at places duplicated. Hypertrophic pericytes exhibited remarkable oedamatous changes, increased vesicular or vascular transport, demonstrating pericyte brain-barrier dysfunction. Swelling of the astrocytic end-feet bordering the capillaries was remarkable. These findings indicate that the CSF or oedema fluid is absorbed into the vascular system via a transendothelial pathway.

The effect of cigarette smoke on aryl-hydrocarbon hydroxylase (AHH) activity of the human kidney

AHH activity was measured in kidney cortex biopsies obtained during surgery from patients with hydronephrosis and from unaffected portions of kidneys with renal cell carcinomas. AHH activity was slightly, but not significantly, higher in the group of non-smoking cancer patients when compared to non-smoking hydronephrotic subjects. Smoking induced a significant increase of AHH activity in the hydronephrotic kidneys but not in cancer kidneys, probably due to the higher baseline values and scatter in the cancer group. Pooling cancer and non-cancer kidneys, smokers had a higher AHH activity than non-smokers, this increase being dose-related.

Aldosterone production by sheep adrenal glands in vitro

A novel technique for the preparation of adrenal tissue from large animals (sheep) is presented. Multiple adrenal cortex biopsies are taken using a 2 mm dia. dermatological punch and homogeneous pools of 10 tissue cylinders (1 from each gland) were incubated. Aldosterone, corticosterone and cortisol in the incubation medium were measured by double isotope derivative dilution assay. The mean within-incubation coefficient of variation of aldosterone production was 15.8%, whilst between days. unstimulated aldosterone production ranged from 0.02–0.25 μg/100 mg tissue/2 h. Aldosterone production was stimulated by ACTH, angiotensin II and potassium ions, in a manner similar, but at higher doses, to that reported for sheep in vivo. Serotonin (10 −3 mol/1) inhibited aldosterone production, lower concentrations having no effect. Substrate levels of progesterone, DOC and corticosterone (25 μg/ml) stimulated aldosterone output whilst cortisol inhibited aldosterone production. The incubation system described is simple with a high degree of reproducibility and has the advantage that up to 30 comparable incubation flasks can be prepared for any incubation, thus providing a simple technique for testing possible agonists or antagonists of steroid production.