Cardiorespiratory and renal responses to arterial chemoreceptor stimulation by hypoxia or almitrine in men

1. The cardiorespiratory and renal responses to 3 h of normobaric whole-body hypoxic hypoxia (FiO2 = 0.12) as well as to arterial chemoreceptor stimulation by the oral administration of 100 mg almitrine bismesylate during normoxia were measured in 12 normotensive young men undergoing water diuresis. A third series of responses obtained under comparable conditions in the same subjects served as time controls. 2. No significant changes could be detected over time in the parameters measured in control experiments. The subjects reacted to both whole-body hypoxic hypoxia and to pharmacological chemoreceptor stimulation with significant increases in heart rate, tidal volume, minute ventilation and filtration-fraction. Overall renal vascular resistance rose significantly in hypoxia; increases in renal vascular resistance in almitrine experiments were not significant. 3. Renal fractional lithium excretion decreased significantly in response to whole-body hypoxic hypoxia and increased slightly in response to almitrine. Fractional urine and sodium excretion showed negligible changes. 4. The data indicate that, in humans, both almitrine and whole-body hypoxic hypoxia affect not only alveolar ventilation but also renal haemodynamics. 5. The renal electrolyte excretion pattern suggests that under certain circumstances (e.g. dilated renal vascular bed) acute, but well-tolerated, whole-body hypoxic hypoxia can simultaneously stimulate renal proximal tubular sodium reabsorption and inhibit distal tubular sodium reabsorption. The renal tubular responses also indicate that almitrine may influence renal tubular lithium reabsorption by, thus far, unknown mechanisms.

Panel discussion: impact of guidelines on third-party payors and HMOs

Utilization management (preauthorization) has given way to disease management, i.e., the management, by providers in cooperation with third-party payors, of patients and their disease states from beginning to end. Managed-care organizations are seeking guidelines-based cancer disease management programs that result in: lower, more predictable costs; authoritative quality assurance; measured outcomes; reduced preauthorization disputes; and improved management of cases in clinical trials. Guidelines also need to provide some consistency and consensus regarding the management of common clinical problems. Good guidelines help assist managed-care companies gather data, build a more solid utilization management foundation and support a clinically sound disease management program. Aetna's Institutes of Excellence (IOE) program seeks to address the issue of coverage for high-dose chemotherapy and bone marrow transplantation, but can serve as a useful model for the development of comprehensive cancer networks.

Non-modulating hypertension: evidence for the involvement of kallikrein/kinin activity associated with overactivity of the renin-angiotensin system. Successful blood pressure control during long-term Na+ restriction

BACKGROUND

Non-modulating hypertensives are a subset of sodium-sensitive hypertensives characterized by a failure to modulate renal, vascular and adrenal glomerulosa responsivenesses to angiotensin II appropriately.

OBJECTIVE

To investigate the plasma renin activity (PRA) and urinary kallikrein-like activity (Ku) under different sodium conditions in essential hypertensive patients and in the modulating and non-modulating subsets of hypertensives. Additionally, in these groups of patients, the effects on blood pressure of a sustained Na+ restriction were evaluated.

METHODS

Fifteen normotensives (10 men, aged 29 +/- 5 years) and 54 untreated hypertensives (30 men, aged 34 +/- 7 years) were each administered subsequently three different diets containing 240, 140 and 50 mmol/day Na+, each diet for 10 days. At the end of each period, the PRA, Ku, 24 h urinary volume and urinary Na+ excretion were measured. Afterwards, the essential hypertensives were classified as 29 modulating essential hypertensives (MHT, 20 men, aged 32 +/- 7 years) and 25 non-modulating essential hypertensives (NMHT, 10 men, aged 36 +/- 8 years). Non-modulating ones were identified as individuals who failed to increase their effective renal plasma flow and to decrease their filtration fraction by at least 30% from baseline values, 10 days after changing from a low (10 mmol/day) to a high (260 mmol/day) Na+ intake. Blood pressure was measured with a Dinamap 8100 Critikon device. Both PRA and Ku were measured during normal Na+ intake by standard methods. Patients were administered a low-Na+ diet (10-50 mmol/day) for 12 months.

RESULTS

In essential hypertensives, Ku was lower under the three Na+ diets than it was in normotensives (P < 0.01) whereas the PRA was higher in hypertensives only during the low Na+ intake (P < 0.01). The non-modulating patients showed significantly higher PRA levels (4.0 +/- 0.8 ng ml h, P < 0.05) than did modulating ones (2.6 +/- 1.0 ng ml h) or normotensives (2.3 +/- 1.0 ng ml h). Conversely, non-modulating hypertensives had lower Ku (4.1 +/- 1.0 IU/24 h, P < 0.025) than did modulating ones (6.2 +/- 1.0 IU/24 h) or normotensives (7.8 +/- 2.0 IU/24 h). Blood pressure was significantly reduced during low Na+ intake only in normotensives (month 6: 143 +/- 4/94 +/- 2 mmHg; month 12: 139 +/- 5/89 +/- 3 mmHg) compared with baseline values (169 +/- 4/102 +/- 6 mmHg, P < 0.025).

CONCLUSIONS

It was shown that, in non-modulating hypertensives, in addition to an increased PRA, a reduced kallikrein-like activity coexists and seems to be associated with the impaired Na+ handling. Moreover, in these untreated patients the Na+ restriction was able to exert an antihypertensive effect even for long periods.

Cardiorespiratory and renal responses to arterial chemoreceptor stimulation in early hypertension

The peripheral arterial chemoreceptors (PAC) modify not only cardiorespiratory but also renal hemodynamic and excretory function. There is evidence that in hypertensive animals and humans the reflectoric actions of the PAC on ventilation and circulation differ from those of normotensive subjects. However, the influence of these receptors on kidney function of hypertensive subjects is poorly understood. Cardiorespiratory and renal responses to pharmacological stimulation of PAC by almitrine bismesylate during normoxia were measured in 16 normotensive (NT) and 13 age-matched borderline-hypertensive young men (BHT) undergoing water diuresis. Placebo experiments served as time controls in each subject. NT reacted to almitrine with significant rises in heart rate, minute ventilation, and filtration fraction. Renal vascular resistance tended to increase slightly. In BHT the drug caused a significant rise in heart rate and minute ventilation too, however, this reaction had a longer latency when compared to NT. In contrast to NT, filtration fraction, and renal vascular resistance decreased. Renal fractional sodium and lithium excretion did not show any clear response to almitrine in NT, but decreased in BHT. The results suggest that the weaker ventilatory response in BHT vs. NT might indicate a lower reactivity of their PAC to almitrine. The different reactions of the renal vascular bed to pharmacological chemoreceptor excitation in mild hypertensives might result from a different reactivity of the renal arterioles, whereas the enhanced proximal tubular sodium reabsorption could be due to an exaggerated increase in efferent renal nerve activity.

Comparison of a spectrophotometric microdilution method with RPMI-2% glucose with the National Committee for Clinical Laboratory Standards reference macrodilution method M27-P for in vitro susceptibility testing of amphotericin B, flucytosine, and fluconazole against Candida albicans

The National Committee for Clinical Laboratory Standards has proposed a reference broth macrodilution method for in vitro antifungal susceptibility testing of yeasts (the M27-P method). This method is cumbersome and time-consuming and includes MIC endpoint determination by visual and subjective inspection of growth inhibition after 48 h of incubation. An alternative microdilution procedure was compared with the M27-P method for determination of the amphotericin B, flucytosine, and fluconazole susceptibilities of 8 American Type Culture Collection strains (6 of them were quality control or reference strains) and 50 clinical isolates of candida albicans. This microdilution method uses as culture medium RPMI 1640 supplemented with 18 g of glucose per liter (RPMI-2% glucose). Preparation of drugs, basal medium, and inocula was done by following the recommendations of the National Committee for Clinical Laboratory Standards. The MIC endpoint was calculated objectively from the turbidimetric data read at 24 h. Increased growth of C. albicans in RPMI-2% glucose and its spectrophotometric reading allowed for the rapid (24 h) and objective calculation of MIC endpoints compared with previous microdilution methods with standard RPMI 1640. Nevertheless, good agreement was shown between the M27-P method and this microdilution test. The MICs obtained for the quality control or reference strains by the microdilution method were in the ranges published for those strains. For clinical isolates, the percentages of agreement were 100% for amphotericin B and fluconazole and 98.1% for flucytosine. These data suggest that this microdilution method may serve as a less subjective and more rapid alternative to the M27-P method for antifungal susceptibility testing of yeasts.

NMDA-receptor-mediated synaptic currents in guinea pig laterodorsal tegmental neurons in vitro

1. Whole cell voltage-clamp techniques were used to record glutamate-receptor-mediated synaptic currents from neurons of the laterodorsal tegmental nucleus (LDT). The principal cells of the LDT contain acetylcholine and nitric oxide synthase, and are believed to be involved in the control of sleep-waking behavior via widespread projections to the thalamus and brain stem. LDT cells were recorded from slices of mature guinea pig brain stem with patch pipette solutions containing cesium as the primary cation. 2. Application of N-methyl-D-aspartate (NMDA) elicited currents that were strongly voltage dependent with a mean reversal potential of +16.3 mV. Peak currents occurred near -15 mV, and a region of negative slope conductance was seen at more negative potentials. Application of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid evoked currents that exhibited a nearly linear current-voltage relation with a mean reversal potential of -3.4 mV. 3. Electrical stimulation of local afferents elicited dual-component excitatory postsynaptic currents (EPSCs) with decays that were well fitted by the sum of two exponentials. Mean decay time constants at -60 mV were 8.77 ms for the faster component and 129.4 ms for the slower component. The faster component displayed a linear current-voltage relation and was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or 6,7-dinitroquinoxaline-2,3-dione, indicating that it was mediated by non-NMDA receptors, whereas the slower component displayed a voltage dependence similar to that for NMDA-evoked currents and was blocked by 2-amino-5-phosphonopentanoic acid (AP-5), indicating its mediation by NMDA receptors. 4. The fractional contribution of NMDA receptors to the EPSC was estimated from double-exponential curve fits to the decay phases. With this method, NMDA receptors were estimated on average to carry 10.1% of the total peak EPSC at -60 mV. Blockade of the non-NMDA-receptor-mediated component with CNQX revealed a residual EPSC whose amplitude was 14.4% of the control value, whereas AP-5 alone reduced the control EPSC peak by 16.1%, both values were comparable with those obtained from curve fit estimates. 5. Previous work has shown that the presence of 4-aminopyridine-sensitive, A-like transient current in LDT cells is correlated with the cholinergic phenotype. The majority of cells in this study exhibited A-like transient currents that were blocked by 4-amino-pyridine, suggesting that the majority of the data were obtained from the cholinergic and NOS-containing neurons of the LDT nucleus. 6. These experiments demonstrate the synaptic activation of functional NMDA and non-NMDA receptors in LDT neurons, and indicate that NMDA receptors contribute to fast excitatory transmission in these cells. The results suggest that afferents releasing excitatory amino acids may play an important role in controlling the state-dependent activity of LDT neurons.

Herpes simplex virus infection in burned patients: epidemiology of 11 cases

Burned patients suffer significant immunosuppression during the first 3 or 4 weeks after hospitalization. Herpes simplex virus (HSV) infections are commonly seen in immunosuppressed patients and may account for considerable morbidity and some mortality. We studied retrospectively 11 patients with severe burn injury who became infected with HSV. We determined the prevalence of viral infection in this group of patients. Serological testing and viral culture was used to diagnose HSV infection. No general complications appeared in these 11 patients in association with HSV but two patients died of multiorgan failure. Locally, areas of active epidermal regeneration were most commonly affected. Acyclovir therapy was not used and the duration of hospitalization was normal in these 11 patients.

Intratumoral heterogeneity and inverse correlation between expression of E-cadherin and collagenase type IV in human gastric carcinomas

We examined the expression of E-cadherin and collagenase type IV in formalin-fixed, paraffin-embedded specimens of human gastric carcinoma by an in situ mRNA hybridization (ISH) technique. The ISH technique revealed intertumoral heterogeneity for expression of E-cadherin and collagenase among 12 cases of early gastric cancer and 13 cases of advanced gastric cancer. In the majority of the tumors, we found an inverse relationship between the reactivities of E-cadherin and collagenase type IV. Specifically, E-cadherin was expressed at higher levels in the center of the neoplasms than in their periphery, whereas collagenase type IV was expressed at a higher level in the periphery (invasive edge) than in the center. Advanced gastric cancers with high levels of expression for collagenase type IV in the periphery had a higher incidence of distant lymph node metastasis than those with low expression. The data show an inverse relationship between E-cadherin (involved in cell-to-cell adhesion) and collagenase type IV (involved in invasion) in different zones of human gastric carcinoma and suggest that the relative expression of these independent genes may be involved in local invasion and metastasis.

Cell density-dependent modulation of basic fibroblast growth factor expression by human interferon-beta

The production of basic fibroblast growth factor (bFGF) by human renal cell carcinoma (HRCC) is associated with induction of angiogenesis. Incubation of HRCC cells with human interferon alpha (IFN-alpha) or interferon beta (IFN-beta) downregulates the expression of bFGF and, hence, angiogenesis. The purpose of this study was to analyze the downregulation of the expression of bFGF in HRCC cells by IFN-alpha and IFN-beta. Human HRCC SN12PM6 cells cultured under sparse conditions expressed 3-7-fold higher levels of steady-state bFGF-specific mRNA transcripts and cellular bFGF protein than did confluent cultures. IFN-alpha or IFN-beta inhibited the steady-state expression of bFGF mRNA transcripts and cellular bFGF protein in a concentration-dependent manner in sparse but not confluent cultures. Moreover, IFN-beta downregulated the transcription rate of bFGF genes and inhibited the de novo synthesis of bFGF protein only in sparse cultures. The results demonstrate that the inhibitory effects of IFN- and -beta on bFGF expression are cell-density dependent.

Sperm selection methods for intracytoplasmic sperm injection (ICSI) in andrological patients

PURPOSE

To improve the chances of successful in vitro fertilization, spermatozoa have to be separated from semen before insemination. Therefore, sperm preparation methods are of great importance.

METHODS

To obtain sufficient numbers of spermatozoa from patients with cryptozoospermia or severe OAT syndrome, only Minipercoll centrifugation and migration-sedimentation (MS) are practicable methods. The present study was performed to compare these two methods with regard to sperm concentration, motility, vitality, morphology, and chromatin condensation. The number of spermatozoa obtained after minipercoll was higher than that after MS, but sperm quality in all parameters examined was clearly better after MS than after Minipercoll. In the second stage of this study, the MS method was used for preparation of the spermatozoa for intracytoplasmic sperm injection (ICSI).

RESULTS

Over a period of 13 months, 159 cycles were treated by ICSI. Of 1045 aspirated oocytes, 790 were injected. The fertilization rate was 70.4% of injected oocytes (556 oocytes with clearly visible pronuclei). In 146 cases, embryonic transfer was achieved; 58 patients became pregnant (39.7% per transfer and 36.5% per cycle).

CONCLUSIONS

Although the abortion rate was very high (18 women lost their embryos), the results demonstrate that the microinjection method can be successfully used in combination with a MS method for preparation of spermatozoa.

Cell density-dependent regulation of basic fibroblast growth factor expression in human renal cell carcinoma cells

We investigated some of the mechanisms that regulate the expression of basic fibroblast growth factor (bFGF) in human renal cell carcinoma (HRCC). HRCC SN12PM6 cells were cultured as adherent monolayers. The expression of steady-state bFGF mRNA (measured by in situ hybridization and Northern blot) and protein (measured by immunohistochemistry and ELISA) correlated inversely with the culture density. Tumor cells harvested from dense cultures (low bFGF expression) and plated under sparse conditions expressed high levels of bFGF mRNA and protein prior to cell division, suggesting that bFGF may be a competence factor. Similar data were obtained with human vascular endothelial cells. The expression of bFGF was not regulated by spent culture medium, cell cycle, or rate of cell division but was down-regulated by contract inhibition. These data show that the expression of bFGF in HRCC is cell density dependent.

Leukemia cutis: Darier's sign in a neonate with acute lymphoblastic leukemia

Infantile leukemia accounts for only 3% of childhood leukemia. Leukemia cutis occurs in 25% to 30% of infants with congenital leukemia and is more frequently associated with acute myeloid leukemia than with acute lymphoblastic leukemia. We describe an infant in whom hyperpigmented macules that developed when the patient was 2 weeks old demonstrated Darier's sign when he was 4 weeks old. Acute lymphoblastic leukemia, early pre-B-cell type, was diagnosed when the patient was 10 weeks old. Examination at that age revealed 1 to 2 cm, firm, mildly tender nodules clustered on the scalp, face, and extremities, less severe involvement of the trunk, and marked induration of the face and eyelids. Darier's sign was elicited from the less infiltrated truncal lesions. Histologic examination revealed a dense monomorphous infiltrate consisting of pleomorphic, undifferentiated cells. No mast cells were revealed by Giemsa staining. This case is to our knowledge the first reported example of leukemia cutis demonstrating Darier's sign.

[Role of albumins in burnt patients: its efficacy during intensive care. Addendum to the expert guidelines of the Consensus Conference, Paris December 15th 1995]

In the burned patient, the critical threshold over which a correction of hypoalbuminemia is required has not yet been clearly defined. The level of 30 g.L-1 of albumin is usually admitted. According to the extent of the burn, albumin is not indicated in patients with a burn size below 15% of the total body surface. It is essential, from the very beginning of management in patients with a burn size over 50%. Its administration can be postponed to the 8th, 12th or even 24th hour in case of a burn size between 15 and 50%.

Structure-function relationships and molecular genetics of the 3 beta-hydroxysteroid dehydrogenase gene family

The isoenzymes of the 3 beta-hydroxysteroid dehydrogenase/5-ene-4-ene-isomerase (3 beta-HSD) gene family catalyse the transformation of all 5-ene-3 beta-hydroxysteroids into the corresponding 4-ene-3-keto-steroids and are responsible for the interconversion of 3 beta-hydroxy- and 3-keto-5 alpha-androstane steroids. The two human 3 beta-HSD genes and the three related pseudogenes are located on the chromosome 1p13.1 region, close to the centromeric marker D1Z5. The 3 beta-HSD isoenzymes prefer NAD+ to NADP+ as cofactor with the exception of the rat liver type III and mouse kidney type IV, which both prefer NADPH as cofactor for their specific 3-ketosteroid reductase activity due to the presence of Tyr36 in the rat type III and of Phe36 in mouse type IV enzymes instead of Asp36 found in other 3 beta-HSD isoenzymes. The rat types I and IV, bovine and guinea pig 3 beta-HSD proteins possess an intrinsic 17 beta-HSD activity specific to 5 alpha-androstane 17 beta-ol steroids, thus suggesting that such "secondary" activity is specifically responsible for controlling the bioavailability of the active androgen DHT. To elucidate the molecular basis of classical form of 3 beta-HSD deficiency, the structures of the types I and II 3 beta-HSD genes in 12 male pseudohermaphrodite 3 beta-HSD deficient patients as well as in four female patients were analyzed. The 14 different point mutations characterized were all detected in the type II 3 beta-HSD gene, which is the gene predominantly expressed in the adrenals and gonads, while no mutation was detected in the type I 3 beta-HSD gene predominantly expressed in the placenta and peripheral tissues. The mutant type II 3 beta-HSD enzymes carrying mutations detected in patients affected by the salt-losing form exhibit no detectable activity in intact transfected cells, at the exception of L108W and P186L proteins, which have some residual activity (approximately 1%). Mutations found in nonsalt-loser patients have some residual activity ranging from approximately 1 to approximately 10% compared to the wild-type enzyme. Characterization of mutant proteins provides unique information on the structure-function relationships of the 3 beta-HSD superfamily.

A serological study on infection patterns, control and persistence of classical swine fever in infected farms in the Philippines

In 3 farrow-to-finish farms with enzootic classical swine fever (CSF) all sick pigs were culled and an intensive vaccination program was introduced. Boars and cows were vaccinated every 6 months and piglets at the age of 6 and 8 weeks. The infection was monitored on clinical grounds and by means of serological examination of the farms. Serological results reflected well the clinical situation in the farms. High titers and high percentage of animals with positive titers were observed in infected farms, compared to lower titers in a clinically "free" farm, which were interpreted as titers due to vaccination. Although clinical improvement was noticed, the rigid vaccination regime was not able to control CSF in none of the farms. In all cases, a small percentage of pigs in the finishing stage was still affected. Since these pigs seemed not to have responded to vaccination at 6 and 8 weeks of age, the programme was questioned. Additionally, very high titers were recorded in sows from infected farms, which would automatically extend the period of passive protection in offspring and postpone the age at which piglets could be vaccinated. More intensive programmes, which include also vaccination beyond the age of 8 weeks, were suggested to bring enzootic infections under control.

Assessment of vitamin and trace elementsupplementation in severely burned patients undergoing long-term parenteral and enteral nutrition

The efficacy of an oral supplement of vitamins and trace elements during a longterm artificial parenteral and enteral nutrition was investigated for 3 months in patients with extensive burns. Thirty severely burned patients (22 male, 8 female, age 41 +/- 18 years, range 23-59 years, 33 +/- 12% total body surface area burn, 22% +/- 8 full thickness burn surface area) were included. Every 10 days, from day 10 until day 90, we determined serum levels of: *vitamins B1, B12, A, E, *folic acid, *copper, zinc, iron, *transferrin, albumin, prealbumin, total proteins, *fibronectin, retinol binding protein (RBP), *calcium, *phosphorus, *triglycerides, *total cholesterol, *C reactive protein (CRP), *erythrocyte folic acid. The mean daily nutritional support was 60 Kcals and 0.4 g N per kg of body weight, 70% enterally and 30% parenterally administered, with enteral vitamin and trace element supplementation. On day 10, there was a decrease of the serum level of 19/20 parameters. For 8 parameters (vitamin A, total cholesterol, iron, transferrin, fibronectin, phosphorus, RBP, total proteins), the level was lower than usual. Between day 10 and day 20, a significant normalization of 6 of them was noted, the average levels of transferrin and iron remaining below normal values until day 50. There was a significant decrease in C-reactive protein levels, however above normal limits. No deficiency in vitamins or trace elements was found. Cyclic variations of serum levels occurred which may be more related to volemic, hydroelectrolytic, endocrine and inflammatory disorders than to nutritional problems.

Nonsalt-losing male pseudohermaphroditism due to the novel homozygous N100S mutation in the type II 3 beta-hydroxysteroid dehydrogenase gene

Recently, the structure of two genes encoding isoenzymes responsible for 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) activity in the human was elucidated. This activity is an essential step in the biosynthesis of all classes of steroid hormones. In the classic severe form of 3 beta HSD deficiency, patients present with adrenal insufficiency, various degrees of salt loss, and incomplete masculinization in males. Here we report the characterization of the molecular basis of congenital adrenal hyperplasia due to 3 beta HSD deficiency in a male pseudohermaphrodite born from consanguineous parents and having no clinical salt loss. To analyze the structure of the type I and II 3 beta HSD genes of the patient, DNA fragments, generated by polymerase chain reaction amplification of the four exons and the exon-intron boundaries of these genes, were directly sequenced. The patients carried a homozygous missense mutation converting Asn100 to Ser in exon 3 of his type II 3 beta HSD gene. His parents were heterozygous for the same point mutation. The absence of clinical salt loss associated with a male pseudohermaphroditism suggested that 3 beta HSD activity was impaired to different levels in the testes and adrenal. To elucidate whether this N100S missense mutation affected preferentially a steroidogenic pathway, enzymatic activity was analyzed by in vitro analysis of mutant recombinant enzyme generated by site-directed mutagenesis after its transient expression in COS-1 cells. Using homogenates from transfected cells, the N100S 3 beta HSD enzyme showed a Km value for pregnenolone of 25 +/- 3 mumol/L compared with 3.5 +/- 0.2 mumol/L for the normal human type II 3 beta HSD enzyme. Similar results were obtained using dehydroepiandrosterone as substrate. In addition to decreasing apparent affinity, the N100S mutation decreased the relative specific activity (Vmax), leading to a relative specificity (relative Vmax/Km) 2.7% and 11% that of normal type II 3 beta HSD using pregnenolone or dehydroepiandrosterone as substrate, respectively. Moreover, the mutant N100S protein had an apparent decreased affinity for NAD+, with a Km value of 650 +/- 66 mumol/L compared with 20 +/- 2 mumol/L for normal type II 3 beta HSD. Except for the hypothetical effect of local factors, these findings suggest that a very weak residual activity of the normal type II 3 beta HSD enzyme could prevent salt loss, but it was insufficient for normal male sex differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular basis of human 3 beta-hydroxysteroid dehydrogenase deficiency

The enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) catalyses an essential step in the biosynthesis of all classes of steroid hormones. Classical 3 beta-HSD deficiency is responsible for CAHII, a severe form of congenital adrenal hyperplasia (CAH) that impairs steroidogenesis in both the adrenals and gonads. Newborns affected by 3 beta-HSD deficiency exhibit signs and symptoms of adrenal insufficiency of varying degrees associated with pseudohermaphroditism in males, whereas females exhibit normal sexual differentiation or mild virilization. Elevated ratios of 5-ene-to 4-ene-steroids appear as the best biological parameter for the diagnosis of 3 beta-HSD deficiency. The nonclassical form has been suggested to be related to an allelic variant of the classical form of 3 beta-HSD as described for steroid 21-hydroxylase deficiency. To elucidate the molecular basis of the classical form of 3 beta-HSD deficiency, we have analysed the structure of the highly homologous type I and II 3 beta-HSD genes in 12 male pseudohermaphrodite 3 beta-HSD deficient patients as well as in four female patients. The 14 different point mutations characterized were all detected in the type II 3 beta-HSD gene, which is the gene predominantly expressed in the adrenals and gonads, while no mutation was detected in the type I 3 beta-HSD gene predominantly expressed in the placenta and peripheral tissues. The finding of a normal type I 3 beta-HSD gene provides the explanation for the intact peripheral intracrine steroidogenesis in these patients and increased androgen manifestations at puberty. The influence of the detected mutations on enzymatic activity was assessed by in vitro expression analysis of mutant enzymes generated by site-directed mutagenesis in COS-1 cells. The mutant type II 3 beta-HSD enzymes carrying mutations detected in patients affected by the salt-losing form exhibit no detectable activity in intact transfected cells, whereas those with mutations found in nonsalt-loser index cases have some residual activity ranging from approximately 1-10% compared to the wild-type enzyme. Although in general, our findings provide a molecular explanation for the enzymatic heterogeneity ranging from the severe salt-losing form to the clinically inapparent salt-wasting form of the disease, we have observed that the mutant L108W or P186L enzymes found in a compound heterozygote male presenting the salt-wasting form of the disease, has some residual activity (approximately 1%) similar to that observed for the mutant N100S enzyme detected in a homozygous male patient suffering from a nonsalt-losing form of this disorder.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of human papillomavirus type 16 associated squamous cell carcinoma of the scrotum in a patient with Darier's disease treated with systemic isotretinoin

In contrast to squamous cell carcinoma of the penis, scrotal carcinoma has historically been associated with exposure to environmental or industrial carcinogens and has only rarely been correlated with human papillomavirus. We report on a patient with squamous cell carcinoma of the scrotum in which human papillomavirus type 16 was integrated into the tumor cell genome, suggesting a causal role of human papillomavirus in the development of squamous cell carcinoma of the scrotum. Other unique features of our case include the presence of Darier's disease, an uncommon genodermatosis, and treatment with oral retinoids, which have prophylactic value in the prevention of cutaneous malignancies.

Interferons alpha and beta down-regulate the expression of basic fibroblast growth factor in human carcinomas

We investigated the influence of interferons alpha, beta, and gamma (IFN-alpha, -beta, and -gamma) on the production of basic fibroblast growth factor (bFGF) by human renal carcinoma cells. The human renal carcinoma cell metastatic line SN12PM6 was established in culture from a lung metastasis and SN12PM6-resistant cells were selected in vitro for resistance to the antiproliferative effects of IFN-alpha or IFN-beta. IFN-alpha and IFN-beta, but not IFN-gamma, down-regulated the expression of bFGF at the mRNA and protein levels by a mechanism independent of their antiproliferative effects. Down-regulation of bFGF required a long exposure (> 4 days) of cells to low concentrations (> 10 units/ml) of IFN-alpha or IFN-beta. The withdrawal of IFN-alpha or IFN-beta from the medium permitted SN12PM6-resistant cells to resume production of bFGF. The incubation of human bladder, prostate, colon, and breast carcinoma cells with noncytostatic concentrations of IFN-alpha or IFN-beta also produced down-regulation of bFGF production.

Identification and characterization of the G15D mutation found in a male patient with 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) deficiency: alteration of the putative NAD-binding domain of type II 3 beta-HSD

We report the detection of a homozygous G to A mutation converting codon Gly15 into Asp15 in the type II 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) gene in a male pseudo-hermaphrodite born from consanguineous parents and suffering from severe salt-losing 3 beta-HSD deficiency. To investigate further the potential involvement of residue 15 in the beta alpha beta dinucleotide-binding fold, we have studied the effect of substituting Gly15 for Ala15. We assessed the effect of the G15D and G15A missense mutations on enzymatic activity by analyzing mutant enzymes generated by site-directed mutagenesis of type II 3 beta-HSD cDNA after their transient expression in COS-1 cells. In intact transfected cells, after a 2-h incubation, the percentage of conversion of [3H]pregnenolone (PREG) into [3H]progesterone (PROG) was 35% and 50% for the G15A and native type II 3 beta-HSD enzymes, respectively, whereas no detectable activity was observed in cells expressing the G15D protein. This finding is in agreement with the severity of the disease in the homozygote G15D index case. On the other hand, in homogenates from cells transfected with the normal pCMV-type II 3 beta-HSD plasmid or with the mutated pCMV-G15D or pCMV-G15A plasmid, the Km values for PREG were 0.72 microM, 3.2 microM, and 3.4 microM, respectively, when incubated for 1 h in the presence of excess (1 mM) NAD+. Moreover, the expressed G15D and G15A proteins had decreased affinities for NAD+ with Km values of 113 microM and 148 microM, respectively, compared with 22 microM for normal type II 3 beta-HSD.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of anesthesia on sperm motility in gamete intrafallopian transfer

The existence of a motility-inhibiting substance in human peritoneal fluid (hPF) has been demonstrated. The results of this study indicate that this factor from hPF is a heat-resistant, volatile molecule with a very small molecular mass (e.g., halothane, which is used for general anesthesia in laparoscopic GIFT). This may be the reason for the conflicting results concerning pregnancy rates in gamete intrafallopian transfer.

Molecular basis of congenital adrenal hyperplasia in two siblings with classical nonsalt-losing 3 beta-hydroxysteroid dehydrogenase deficiency

We report mutations of the type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) gene in two siblings, male and female, with congenital adrenal hyperplasia caused by classical nonsalt-losing 3 beta HSD deficiency. During childhood, the male sibling, born with ambiguous genitalia, and the female sibling, born with normal genitalia, both manifested symptoms of mild androgen excess; both apparently had normal zona glomerulosa function. Gonadal dynamic study at puberty showed the presence of partial gonadal 3 beta HSD deficiency in both siblings despite their spontaneous pubertal maturation. The 5'-region as well as exons I-II, III, and IV and portions of the adjacent introns of the type II 3 beta HSD gene were amplified by polymerase chain reaction and sequenced. In both siblings and their mother, an identical single nucleotide substitution mutation in intron III, six bases up-stream from exon IV, was identified in one allele. This mutation, G to A at nucleotide 6651, may create a new splicing junction and affect the normal splicing of the messenger ribonucleic acid. In the other allele of both siblings, a missense mutation from GGG (Gly) to AGG (Arg) at codon 129 (G129R) in exon IV was found. We assessed the effect of the G129R missense mutation on enzymatic activity by in vitro analysis of the mutant recombinant enzyme generated by site-directed mutagenesis after its transient expression in COS-1 cells. Using homogenates from transfected cells, the G129R 3 beta HSD enzyme showed a Km value for pregnenolone of 10 +/- 2 mumol/L compared with 1.00 +/- 0.03 mumol/L for the wild-type type II 3 beta HSD enzyme. When dehydroepiandrosterone was used as substrate, the Km value for G129R3 beta HSD was 14 +/- 2 mumol/L compared with 2.1 +/- 0.2 mumol/L for the wild-type II 3 beta HSD enzyme. In addition to an apparent decrease in affinity, the G129R mutation caused a marked decrease in the apparent relative specific activity, thus leading to apparent relative specific efficiencies (relative specific activity/Km) of 2.0% and 4.7% that of the normal type II 3 beta HSD using pregnenolone or dehydroepiandrosterone as substrate, respectively. It appears likely that this low level of activity is sufficient to prevent salt loss, but it is also possible that part of the enzymatic activity comes from the putative remaining percentage of correctly spliced n6651 allele in these patients.

NMDA receptor-mediated synaptic input to nitric oxide synthase-containing neurons of the guinea pig mesopontine tegmentum in vitro

Intracellular recordings were obtained from laterodorsal tegmental (LDT) and pedunculopontine tegmental (PPT) neurons in a slice preparation to determine if excitatory synaptic input to the nitric oxide synthase (NOS)-containing cells was mediated by NMDA receptors. NOS cells were identified by intracellular injection of biocytin and NADPH-diaphorase histochemistry. Application of NMDA produced membrane depolarization, and EPSPs were reversibly reduced by an average of 46.3 +/- 16.6% with AP-5 (50 microM). These results indicate that post-synaptic NMDA receptors participate in synaptic transmission to NOS-containing neurons in LDT and PPT and are consistent with the hypothesis that synaptic NMDA receptors may control NO production in these cells.

Oncogenes and cellular-sensitivity to radiotherapy - a study on murine keratinocytes transformed by v-h-ras, v-myc, v-Neu, adenovirus e1a and mutant p53

Mechanisms involved in cellular radioresistance are mostly unknown and may be related to specific genetic alterations. In order to correlate the most frequent oncogenic alterations detected in tumors and ionizing radiation resistance, we studied the effect of irradiation on murine keratinocytes transformed by different oncogenes. Mouse PAM 212 keratinocytes were transformed by transfection or retroviral mediated infection with the oncogenes v-H-ras, v-myc, adenovirus Ela, neu and a mutant p53 (mp53). Cells were gamma irradiated with a Co-60 source. Cell viability was evaluated by the crystal violet method and thymidine uptake and data adjusted to the linear-quadratic model. Surviving fraction 2Gy (SF2) and DO was calculated. Cell cycle study was assessed by incorporation of bromodeoxyridine (BrdUrd) and flow cytometry. p53 protein was studied by Western-blot and apoptosis in DNA agarose gels. The surviving fraction for the different keratinocytes, PAM 212, 212 neo, 212 Ela, 212 v-H-ras, 212 myc, 212 neu and 212 mp53 was 0.79, 0.78, 0.34, 0.82, 0.68, 0.74, and 0.72, respectively. Ela oncogene induced a great sensitivity to irradiation and v-H-ras a mild radioresistance. In flow cytometry, 212 Ela keratinocytes displayed a pronounced and prolonged arrest in G2/M phase. Apoptosis was observed after irradiation only in the 212 Ela keratinocytes. With these results, we conclude that some oncogene products may modulate radiosensitivity in keratinocytes. Mechanisms involved in radiosensitivity mediated by the Ela oncogene seem to be related to p53 protein level, induction of apoptosis and to an irreversible premitotic arrest in G2/M phase, ineffective for repair of DNA damage.

Functional characterization of the novel L108W and P186L mutations detected in the type II 3 beta-hydroxysteroid dehydrogenase gene of a male pseudohermaphrodite with congenital adrenal hyperplasia

Two isoenzymes are responsible for 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) activity in humans. We analyzed the structure of types I and II 3 beta-HSD genes in a male pseudohermaphrodite suffering from a severe salt-losing form of congenital adrenal hyperplasia. We did not detect any mutation in the type I 3 beta-HSD gene, but we found two different missense mutations in exon IV of the type II 3 beta-HSD gene of the patient; a conversion of codon Leu108 into a Trp (L108W) inherited from his mother and a conversion of codon Pro186 into a Leu (P186L) inherited from his father. We assessed the effect of the L108W and P186L mutations on 3 beta-HSD activity by in vitro analysis of mutant enzymes expressed in heterologous COS-1 cells. Using homogenates from transfected cells, the Km values for PREG were 7 +/- 2 and 8 +/- 2 microM for the recombinant L108W and P186L enzymes, respectively, compared with 2.2 +/- 0.2 microM for the normal type II 3 beta-HSD enzyme. Moreover, Km values for NAD+ were much higher for the L108W and P186L proteins, being 678 +/- 166 and 920 +/- 351 microM, respectively, compared with 24 +/- 3 microM for the normal type II 3 beta-HSD enzyme. Vmax values for PREG and NAD+ were lower for both mutant enzymes; thus, the in vitro overall efficiency, relative to the normal enzyme, is approximate as 0.3% and 0.2% for the L108W and P186L enzymes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The efficacy of routine head computed tomography (CT scan) prior to lumbar puncture in the emergency department

The efficacy of using unenhanced head computed tomography (CT scans) as a routine screening procedure prior to lumbar puncture in the emergency department is studied retrospectively by comparing opening pressure during lumbar puncture to CT scan diagnosis in 42 patients. No correlation was found between CT scan findings and opening pressure.

Chordomas of the skull base. Radiologic and clinical evaluation

Chordomas are uncommon skull base tumors, which are locally agressive and are usually not amenable to complete surgical resection. Proton beam irradiation, following surgery, is the preferred treatment modality. For diagnosis and determination of tumor site and extension, CT and MR imaging are the imaging modalities of choice. CT delineates bone destruction and the presence of calcifications and destroyed bone optimally. MR imaging is the modality of choice for better definition of the tumor margin from brain and other soft tissue structures (pharynx) and visualization of blood vessels. The signal intensities and enhancement pattern fail to differentiate chordoma from chondroid chordoma or chondrosarcoma. Chordomas arise from the clivus and therefore are located more centrally, whereas the majority of chondrosarcomas originate in the petroclival fissure and occur more laterally, although occasional overlap occurs in about one third of cases. Immunohistochemical methods allow differentiation of pure chordoma from chondroid chordoma and chondrosarcoma. Chordomas have a lower local control rate than chondrosarcomas.

Formation and degradation of dihydrotestosterone by recombinant members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase family

The structures of cDNA clones encoding four members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. The rat type I, type II and the novel type IV are genuine NAD+/H-dependent 3 beta-HSD isoenzymes. On the other hand, the liver-specific type III protein is a specific 3-keto-reductase (3-KSR) that catalyzes the conversion of 5 alpha-androstane-3-one-17 beta-ol (DHT) and 5 alpha-androstane 3,17-dione (A-dione) into their 3 beta-hydroxy metabolites. The aim of the present study was to further characterize the enzymatic properties of rat types I, III and IV, especially their role in the formation and degradation of DHT after transient expression in intact human HeLa cervical carcinoma, JEG-3 choriocarcinoma or SW-13 adrenal cortex adenocarcinoma cells in culture. The expressed type III 3-KSR in intact HeLa cells catalyzed the reduction of DHT into 3 beta-diol, whereas expression of type I 3 beta-HSD in these cell lines had no significant effect on the basal conversion of DHT into 3 beta-diol, but it did increase the formation of DHT from 3 beta-diol. A-dione is the predominant product obtained when DHT and 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) are used as substrates in intact JEG-3 and SW-13 cells transfected with rat type I 3 beta-HSD. Furthermore, this predominant 17 beta-HSD activity was also observed in SW-13 cells transfected with the novel rat type IV 3 beta-HSD. The predominance of this 'secondary' 17 beta-HSD activity is also reflected in HeLa cells transfected with type I 3 beta-HSD by the deduced predominant pathway 3 beta-diol-->DHT-->5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol)-->androsterone (ADT), in which formation of 3 alpha-HSD activity of HeLa cells, whereas the other reactions are catalyzed by the type I 3 beta-HSD isoenzyme. This observation thus demonstrates that rat type I 3 beta-HSD may also catalyze the conversion of 3 alpha-diol into ADT through its intrinsic 17 beta-HSD activity. The predominant metabolic pathways observed in the present study could be attributed to preponderant bioavailability of NAD+ and NADPH in the intact transfected cells used.

Guided tissue regeneration: comparison of bioabsorbable and non-bioabsorbable membranes. Histologic and histometric study in dogs

This study examined histologic and histometric responses to 2 bioabsorbable membranes made from a synthetic copolymer of glycolide and lactide. They were tested for their biocompatibility, resorption characteristics, and ability to support periodontal regeneration. Expanded polytetrafluoroethylene (ePTFE) was used as control. Nine fox hound dogs with no periodontal disease were used. They were sedated and their teeth thoroughly scaled and root planed. Plaque control was maintained. Two weeks later, each dog was anesthetized using gas anesthesia. Buccal and lingual mucoperiosteal flaps were reflected in the mandibular premolar areas. Randomly selected, buccal alveolar bone was reduced on the 2nd and 4th premolars to a level 5 to 8 mm apical to the cemento-enamel junction creating a Class II buccal furcation defect on one quadrant, while the other quadrant received a Class II buccal defect only on the 4th premolar. Root surfaces were denuded of periodontal ligament and cementum, and notches were placed at the bone level of each root. In one quadrant, one site received Type I membrane and the other site received Type II. The contralateral quadrant received ePTFE. Flaps were positioned slightly coronally and sutured. Sutures were removed 1 week later. One month after surgery, 3 dogs were sacrificed and ePTFE barriers were removed from the remaining 6 dogs. Of these, 3 were sacrificed 3 months after surgery and the other 3 at 6 months. Undemineralized experimental tissues were embedded in methylmethacrylate and 8 to 10 microns thick sections were cut in a bucco-lingual direction throughout the mesiodistal extension of the tooth.(ABSTRACT TRUNCATED AT 250 WORDS)

Ocean source and optical property estimation from explicit and implicit algorithms

We solve an inverse problem of ocean optics for estimating spatially dependent absorption and scattering coefficients and for determining sources such as fluorescence, bioluminescence, or Raman scattering. The solution requires in situ measurement of the downward and upward plane irradiances and scalar irradiances and a priori estimation of the angular shape of the volume scattering function. Both an explicit algorithm and an implicit one are developed from new two-stream radiative-transfer equations that utilize an asymptotic radiance approximation to close the set of equations. A comparison of numerical tests for the two algorithms is given.

Detection and functional characterization of the novel missense mutation Y254D in type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) gene of a female patient with nonsalt-losing 3 beta HSD deficiency

Three beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) deficiency is a form of congenital adrenal hyperplasia characterized by severe impairment of steroid biosynthesis in the adrenals and gonads. To better understand the molecular basis of the phenotypic heterogeneity found in 3 beta HSD deficiency, we analyzed the structure of type I and II 3 beta HSD genes in a female patient with nonsalt-losing 3 beta HSD deficiency diagnosed at puberty. We directly sequenced DNA fragments generated by polymerase chain reaction amplification of the four exons, the exon-intron boundaries, and the 5'-flanking regions of each gene. No mutation was detected in the type I 3 beta HSD gene, which is the predominant species expressed in the placenta and peripheral tissues. We detected a novel missense mutation, Y254D, in one allele of the patient's type II 3 beta HSD gene, which is the almost exclusive type expressed in the adrenals and gonads. The influence of the Y254D mutation on enzymatic activity was assessed by analyzing the recombinant mutant enzyme generated by site-directed mutagenesis after its transient expression in COS-1 monkey kidney cells. Recombinant mutant type II 3 beta HSD enzyme carrying the Y254D substitution exhibits no detectable activity with C21 delta 5-steroid pregnenolone or C19 delta 5-steroid dehydroepiandrosterone used as substrate. The absence of restriction fragment length polymorphism by Southern blot analysis and the finding that all of the amplified DNA fragments possess the expected length suggest the absence of deletions, duplications, or re-arrangements in the other allele. A putative second mutation could be located farther than 1427 basepairs upstream of the initiation codon, thus potentially affecting the normal expression of this gene or within intronic regions, generating an alternative aberrant splicing site. These are possibilities that remain to be elucidated. The present findings, which describe the novel missense mutation Y254D in the human type II 3 beta HSD gene, provide useful information on the structure-activity relationships of the 3 beta HSD superfamily.

A model for estimation of the pulmonary capillary pressure

To estimate the pulmonary capillary pressure, a theory was introduced by Holloway and coworkers. Based upon this, a mathematical model describing the measured data was developed. Because the physiologic data are embedded in noise and the pulmonary capillary pressure cannot be measured directly, we simulated an extensive series of data. The noise properties of the data were as analyzed to design a signal-processing tool, that cancels the noise from the measured data. The signal processing tool developed for the current application consists of pre-processing with a moving time average filter and post-processing with a neural network. After a verification procedure the tool can be applied to measured data, hence a more reliable measurement of the pulmonary capillary pressure is achieved.

A comparison of laparoscopically assisted vaginal hysterectomy and abdominal hysterectomy

The goal of this study was to compare laparoscopically assisted vaginal hysterectomy (LAVH) with total abdominal hysterectomy (TAH). We performed a prospective comparison of the hospital courses of 30 women, 15 undergoing LAVH and 15 undergoing TAH, in a teaching hospital setting. Analysis of variance (ANOVA) was used, with statistical evaluation of differences by Student's t-test for normally distributed data and Kruskal-Wallis for data with dissimilar variances. Fourteen of fifteen patients scheduled for LAVH had their surgery completed without need of a laparotomy. In the LAVH group, (1) mean surgical time was 50 minutes longer, (2) blood loss, complications, and hospital costs were not statistically different, (3) hospital days averaged 1 1/2 less, and (4) postoperative pain ratings and medication requirements were significantly decreased, compared with the TAH group. In many cases, LAVH may be reasonably performed instead of an indicated TAH.

Temporal relationship of complications after coronary artery bypass graft surgery: scheduling for safe discharge

The postoperative courses of 224 patients who left the operating room alive after coronary bypass surgery were followed to determine the time of onset of complications to determine when discharge is safe. A total of 155 complications occurred in 103 patients including 59 with supraventricular tachycardia, 17 with fever, and 9 to 11 with ventricular arrhythmias, cerebrovascular accidents, wound infection, or deep vein thrombosis. Pneumonia occurred in seven patients, and other complications occurred in five or fewer patients. Most initial complications (77.6%) occurred by day 5, and 89.3% of the patients with complications had their initial event before day 8. Hence it appears that it is safe to discharge patients on day 8 after coronary artery bypass graft surgery if they have not had a postoperative complication.

Left ventricular perforation by a pleural drainage tube. Report of a case with survival

We present a case of survival as a result of surgical intervention after perforation of the left ventricle during the insertion of a pleural drainage tube. Surgical intervention was facilitated by the fact that the drainage tube responsible for the suspected perforation of the cardiac cavity was clamped and fastened, as opposed to withdrawn. The location of the perforation was established by measuring the pressure curve through the drainage tube.

Inhibition of adhesion of enterotoxigenic Escherichia coli cells expressing F17 fimbriae to small intestinal mucus and brush-border membranes of young calves

Enterotoxigenic Escherichia coli strains expressing F17 fimbriae bind to the intestinal mucosa of young calves. F17 fimbriae recognize receptors present in the mucus layer and the brush-border membranes from duodenum, jejunum and ileum. The adhesion of E. coli F17 can be inhibited by several glycoproteins. Adhesion is also inhibited by pretreatment of mucus and brush-border membranes with sodium metaperiodate. The use of glycoconjugates as potential adhesion-blockers is further discussed.

Structure and tissue-specific expression of a novel member of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family. The exclusive 3 beta-HSD gene expression in the skin

Structures of cDNA clones encoding three members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. To search for potential new types of 3 beta-HSD, rat types I and II 3 beta-HSD cDNAs were used as probes to screen a rat genomic DNA library. Among the clones isolated, one encodes a novel predicted rat 3 beta-HSD isoenzyme, chronologically designated type IV. The corresponding full-length cDNA was thereafter isolated by selective polymerase chain reaction amplification from rat ovary and day-15 placenta cDNA libraries. The rat type IV 3 beta-HSD cDNA encodes a predicted 372-amino acid protein of 41,854 daltons, which shares 90.9, 87.9, and 78.8% sequence identity with rat types I, II, and III proteins, respectively. Ribonuclease protection assay reveals that type IV 3 beta-HSD is the sole 3 beta-HSD mRNA species detectable in the skin and represents the predominant species in the placenta while being also detectable in the ovary and, to a lower degree, in the adrenal gland. Transient expression of type IV cDNA in SW-13 cells indicates 3 beta-HSD activity similar to that of rat type I 3 beta-HSD. The presence of multiple 3 beta-HSD genes should permit differential and tissue-specific regulation of this rate-limiting enzymatic activity essential in the biosynthesis of all classes of steroid hormones in both classical steroidogenic and intracrine peripheral tissues.