Biomedical subjects

J Baron

Publications and source records attributed to J Baron.

At least 19 recordsLinked to original sources

PubMed1992

Clinicopathologic spectrum of primary uveal melanocytic lesions in an animal model.

BACKGROUND: Currently, there are no animal models of primary uveal melanoma in an eye large enough to allow documentation of the clinical evolution of the lesion by either funduscopy or fundus photography. METHODS: The authors induced primary uveal melanocytic lesions in the eyes of Dutch (pigmented) rabbits using a two-stage carcinogenesis protocol involving initiation with 4 weekly topical applications of 10 microliters of a 1% solution of 7,12-dimethyl-benz[a]anthracene (DMBA) in acetone (21 eyes) followed by 12 weekly topical applications of a 10 microliters solution of either 0.25% or 0.5% croton oil in acetone. They also investigated the effect of initiation with DMBA without promotion and the effects of chronic topical exposure to acetone and proparacaine. RESULTS: Exposure to DMBA followed by promotion with croton oil in either concentration was the most effective means of inducing clinically detectable fundus lesions. Histologically, a spectrum of melanocytic proliferations developed including benign nevi, nevi with varying grades of cytologic atypia, and clusters of confluent atypical melanocytes that may represent early melanomas. Although clinical regression of fundus lesions was noted in eight eyes after promotion had been stopped, five of these eyes showed unequivocal histologic evidence of a residual uveal melanocytic lesion. Chronic ocular irritation is capable of inducing cytologically benign subclinical uveal melanocytic proliferations. CONCLUSIONS: The conventional classification of human uveal melanocytic lesions includes only nevi and melanomas, but a comparison of the results of this study with descriptions of human uveal melanocytic nevi suggests the existence of a spectrum of intermediate atypical precursor lesions in humans.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1992

Assessment of intrapelvic cement and screws in revision total hip arthroplasty.

Vascular injury resulting from primary and revision hip arthroplasty has been reported to involve both arterial and venous structures. While such complications are extremely uncommon, removal of intrapelvic cement or screws during revision surgery can be hazardous to intrapelvic structures. Both arterial and venous perforations can occur, depending on the level at which the pelvic wall has been breached, and on the orientation of the intruding matter. Complications can be minimized with careful preoperative assessment of pelvic anatomy. Contrast-enhanced computerized tomography scanning can assist the revision surgeon with preoperative planning in those patients requiring removal of intrapelvic components. This technique appears to be an accurate, simple, and noninvasive method by which these intrapelvic relationships may be examined.

Acetabulum↗

PubMed1992

The effect of normative beliefs on anticipated emotions.

In 3 experiments, Ss were asked how they would or should make hypothetical decisions and how they would react emotionally to the options or outcomes. The choices were those in which departures from proposed normative models had previously been found: omission bias, status quo bias, and the person-causation effect. These effects were found in all judgments, including judgments of anticipated emotion. Arguments against the departures affected judgments of anticipated emotion as well as decisions, even though the arguments were entirely directed at the question of what should be done. In all but one study, effects of these arguments on anticipated emotion were as strong as their effects on decisions or normative beliefs. Thus, in many situations, people think that their emotional reactions will fall into line with their normative beliefs. In other situations, some people think that their emotional reactions have a life of their own. It is suggested that both normative beliefs and anticipated emotions affect decisions.

Attitude↗

PubMed1992

Mutations of the phage lambda nutL region that prevent the action of Nun, a site-specific transcription termination factor.

Phage HK022 encodes a protein, Nun, that promotes transcription termination within the pL and pR operons of its relative, phage lambda. The lambda sequences required for termination had previously been shown to overlap the nut sites, which are essential for transcription antitermination during normal lambda growth. To further specify the Nun target and to determine its relation to the nut sites, we constructed deletion and base substitution mutations of the lambda nutL region and measured Nun-dependent reduction of the expression of a downstream reporter gene. The shortest construct that retained full Nun responsiveness was a 42-bp segment that included both boxA and boxB, sequences that have been implicated in lambda antitermination. Deletion of boxA reduced Nun termination, and deletion of both sequences eliminated Nun termination. Base substitutions in boxA and the proximal portion of boxB impaired Nun termination, while base substitutions between boxA and boxB, in the distal portion of boxB, and immediately downstream from boxB had no appreciable effect. The termination defect of all of the base substitution mutations was relieved by increasing the level of Nun protein; in contrast, the deletions and a multiple-base substitution did not regain full Nun responsiveness at elevated Nun concentrations. We also asked if these mutant nut regions retained their ability to interact with N, the lambda-encoded antitermination protein. A qualitative assay showed that mutations within boxA or boxB reduced interaction, while mutations outside boxA and boxB did not. These data show that (i) the recognition sites for N and Nun overlap to a very considerable extent but are probably not identical and (ii) a high concentration of Nun promotes its interaction with mutant nut sites, a behavior also reported to be characteristic of N.

Bacteriophage lambda↗

PubMed1992

Dexamethasone acts locally to inhibit longitudinal bone growth in rabbits.

Excess glucocorticoid is a potent inhibitor of epiphysial growth. Several mechanisms have been suggested to explain this growth inhibition, including both direct local effects of glucocorticoid on the epiphysial growth plate and indirect systemic effects. Previous studies do not distinguish which of these proposed mechanisms is actually responsible for the growth suppression in vivo. To resolve this controversy, we developed a method for delivering glucocorticoid directly into the rabbit epiphysial growth plate and for accurately measuring the resulting epiphysial growth rate. Five-week-old male rabbits received a local infusion of dexamethasone phosphate (80 ng/microliters, 1 microliters/h) into one proximal tibial growth plate and an infusion of vehicle into the contralateral growth plate. Growth rate was determined by inserting metal pins into the bone immediately adjacent to the growth plate and measuring the change in distance between pins on serial radiographs. This method permitted growth rates to be measured over intervals as short as 3 days, with an error of approximately 5%. Local dexamethasone administration decreased proximal tibial growth rate by 77% compared with the contralateral vehicle-treated tibia (P less than 0.0001). We conclude that excess glucocorticoid causes a rapid potent inhibition of growth by a direct local action on the growth plate.

Animals↗

PubMed1992

The effect of pubertal delay on adult height in men with isolated hypogonadotropic hypogonadism.

To determine whether delay of puberty alters adult height, we retrospectively evaluated the adult height of 41 patients who met rigorous criteria for the diagnosis of isolated hypogonadotropic hypogonadism. The adult height of these patients was compared with the mean height of normal American men at age 18 in the 1979 National Center for Health Statistics survey and with the mean adult height of 50 male normal volunteers who had been studied on the same wards as the patients with hypogonadotropic hypogonadism. The mean adult height of the men with isolated hypogonadotropic hypogonadism was 179.7 cm, which exceeded the height of the 50 control subjects and the normal American men (both 176.8 cm) by 2.9 cm (P less than 0.05 and P less than 0.006, respectively). The mean age at treatment to induce puberty was 20.0 yr, which corresponded to a mean delay in the onset of puberty of more than 8 yr relative to normal males. The final height of the men with hypogonadotropic hypogonadism correlated significantly with the duration of pubertal delay (r = 0.32, P = 0.04). Most of the enhanced mean adult height of the patients with isolated hypogonadotropic hypogonadism was attributable to those patients in whom treatment to induce puberty had been delayed to age 18 or greater. The mean adult height of these patients was 182.4 cm, or 5.6 cm greater than the mean height of the 50 controls or of normal American men (P less than 0.001). The mean adult height of patients whose treatment began between 10 and 17 yr of age was 175.0 cm, which did not differ significantly from that of normal men. We conclude that prolonged delay of puberty (6 or more yr) in men with isolated hypogonadotropic hypogonadism is associated with a modest increase (approximately 5 cm) of adult height.

Adolescent↗

PubMed1992

Combining insulin-like growth factor-I and mean spontaneous nighttime growth hormone levels for the diagnosis of growth hormone deficiency.

There is no gold standard for the diagnosis of GH deficiency. Recent data show that spontaneous GH levels may lack sensitivity, and that GH stimulation tests lack specificity as currently performed. Serum insulin-like growth factor-I (IGF-I) measurements lack both sensitivity and specificity. Some of these problems may be explained by nutritional effects. In children, overnutrition decreases GH and increases IGF-I, while undernutrition decreases IGF-I and increases GH. To overcome these difficulties and improve diagnostic accuracy, we combined mean spontaneous nighttime GH levels with IGF-I levels in a statistically based bivariate model. On a two-dimensional plot of mean spontaneous nighttime GH level (in SD units) vs. IGF-I level (in SD units), we defined a new variable, S (sum) score, where S = (1/square root of 2) x (nighttime mean GH SD+IGF-I SD). While IGF-I (SD) and the mean spontaneous nighttime GH (SD) showed a significant correlation with body mass index, the S score was independent of body mass. We, therefore, used the S score to define a new test for GH deficiency. A child failed this bivariate test if his S score was less than -2 SD. We applied this model to 47 normal children and 48 short or slowly growing children (all prepubertal). We measured spontaneous nighttime GH levels and IGF-I levels in all children. In addition, the short children underwent 3 GH stimulation tests. Forty-six of the 47 normal children passed the bivariate test for GH sufficiency. Twenty-three of the 48 short or slowly growing children failed the bivariate test, whereas only 11 children had an abnormally low mean spontaneous nighttime GH measurement alone. Sixteen of 23 children who were GH deficient by the bivariate test were also GH deficient by the stimulation tests. In summary, the bivariate test for GH deficiency appears 1) to be independent of body mass, unlike either IGF-I or GH individually; 2) to identify more children than the mean spontaneous nighttime GH level alone; and 3) to be highly specific in the normal population, unlike stimulation tests.

Body Mass Index↗

PubMed1992

[Surgical treatment of polycystic ovary syndrome. A. Preoperative examinations].

The aim to study was the determination the effect of operative treatment of 31 patients with polycystic ovary syndrome. Before the operation primarily the authors confirmed at the patients the presence of menstrual abnormalities in 96.8%, of infertility in 100%, of hirsutism I. in 9.7%, II. in 61.8%, III. in 29% and the average level of 17-ketosteroids 16.0 +/- 6.9, of DHEA 3.7 +/- 1.5 mg and of estrogens 39.0 +/- 15.1 mcg in 24 urine, of total testosterone 0.98 +/- 0.24, of FSH 3.4 +/- 1.5, of LH 44 +/- 2.4, of prolactin 11.4 +/- 5.4 and of estradiol 0.32 +/- 0.35 ng/ml in blood. On the basis of clinical, hormonal or/and ultrasonographic examinations the diagnosis of the polycystic ovarian disease was performed.

Adult↗

PubMed1992

[Surgical treatment of polycystic ovary syndrome. B. Postoperative examinations].

After the wedge resection of the ovaries the authors obtained the normal menses in 100%, the reduction of total testosterone in blood of 41.8% and of 17-KS in urine of 20%, an increase of fertility of 62.5% and in hirsutism a correction only of 12%, the stopping of 12% and no correction of 76%. The authors conclude that the cause of the healing or of the correction is placed in the resection of 3/4 of the changed ovaries with cysts follicles with distinct thecal layer what is accompanied by the reduction of testosterone on average of 41.8%. On contrary a weak correction in hirsutism has the explanation that the existent hirsutism is supported even by the normal level of testosterone in organism.

17-Ketosteroids↗

PubMed1991

In situ sites for xenobiotic activation and detoxication: implications for the differential susceptibility of cells to the toxic actions of environmental chemicals.

The findings reported in this communication illustrate that histochemical approaches can provide a significant amount of insight into an area of considerable toxicologic importance. Results of our immunohistochemical and histochemical studies clearly demonstrate that neither xenobiotic-metabolizing enzymes nor oxidative xenobiotic metabolism occur uniformly throughout tissues that often are damaged as a result of the bioactivation of environmental chemicals and other xenobiotics, that there can be significant differences in both the contents and activities of xenobiotic-metabolizing enzymes among even morphologically similar cells such as hepatocytes, and that enzyme inducers can alter differentially the extents to which different cells in a tissue metabolize xenobiotics. Knowledge of the precise intratissue localizations and distributions of xenobiotic-metabolizing enzymes and xenobiotic biotransformation reactions clearly is critical for defining the roles individual cells play in the metabolism of xenobiotics. It must be recognized, however, that the mere presence of xenobiotic-metabolizing enzymes in a cell cannot, by itself, explain why that cell might be highly susceptible to toxicities resulting from the bioactivation of certain xenobiotics. Thus, it is apparent that considerably more study is needed, especially in situ using histologic and cytologic techniques, in order to characterize the balance between xenobiotic activation and detoxication processes within individual cells in target tissues and elucidate the basis for the cell-selective nature of toxicities caused by the generation of reactive metabolites from many xenobiotics.

Animals↗

PubMed1991

Investigating the effect of stimulus range on attribute weight.

Classic economic theories of choice assume that trade-offs are made consistently and are not swayed by irrelevant contextual variables. One possible source of trade-off inconsistency is investigated by asking whether attribute weights are affected by variations in the range of the stimuli presented. Ss should be influenced by the range of the stimuli only when distributional characteristics provide information about the value of the stimuli. In six experiments, Ss made judgments when the range (a) did not provide information about the value of the scores on the scales, (b) might provide such information, and (c) certainly provided this information. In Experiments 1-5, Ss were not influenced by the range of the stimuli. The only exception was Experiment 6, which required Ss to judge hypothetical job candidates on the basis of stimulus scales with which the Ss had no previous experience. In this experiment the meaning of the scales was determined entirely by the location of each stimulus within the presented distribution. In general, the results support the classical view of decision making: that attribute weights exist independent of situational demands, and that Ss' judgments are not influenced by irrelevant stimuli.

Adult↗

PubMed1991

[Endoscopic prosthesis of the biliary tract].

In the years 1987--1989 endoscopic biliary tree stenting was performed in 64 patients. The straight prostheses type Amsterdam 10 or 12 F and double pigtail prostheses were applied. In 36 cases the indication for stenting was malignant stricture of the biliary tree (group I) caused by carcinoma of the ampulla of Vater (n = 12), carcinoma of the head of the pancreas (n = 15), common bile duct and bifurcation tumor (n = 5) and gallbladder cancer (n = 4). In 28 cases the indications were common bile duct stones (group II) where stone size made endoscopic removal impossible and surgery was contraindicated. Normalisation or improvement of elevated serum bilirubin level was observed quite quickly after stenting (it decreased to about 50% of initial value after 7 days). Mean duration of prosthesis patency in group I patients who avoided surgical treatment was 144 days and mean survival time was 220 days. In group II patients mean duration of prosthesis patency was 183 days. Endoscopic biliary tree stenting is an advantageous alternative to surgical palliative++ treatment of obstructive neoplastic jaundice and constitutes an efficient method of treating common bile duct stones in poor operative risk patients.

Adult↗

PubMed1991

Purification, immunochemical characterization, and immunohistochemical localization of rat hepatic aryl sulfotransferase IV.

Aryl sulfotransferases catalyze the formation of sulfuric acid esters from a diverse group of endogenous and xenobiotic organic chemicals. The isoenzyme of aryl sulfotransferase in livers of male Sprague-Dawley rats that exhibits the most varied substrate specificity is aryl sulfotransferase IV. A new method for the purification to homogeneity of aryl sulfotransferase IV was developed that, when compared with previously described procedures, provided a greater than 10-fold increase in total yield of enzyme/g of tissue. Homogeneous aryl sulfotransferase IV was used to prepare polyclonal antibodies in male New Zealand White rabbits. Results of immunochemical analyses demonstrated that these antibodies reacted with only a single protein in rat hepatic 100,000 x g supernatant fractions and, further, that the immunoreactive protein had the isoelectric point and subunit molecular mass characteristic of aryl sulfotransferase IV. Immunohistochemical analyses demonstrated that aryl sulfotransferase IV is present in hepatocytes throughout the liver, although centrilobular cells contain a significantly greater (p less than 0.01) amount of aryl sulfotransferase IV than do either midzonal or periportal cells, in which similar levels of the enzyme are found.

Animals↗

PubMed1990

[Surgical removal of a giant intracranial tumor (medulloblastoma) in a child--patient's chances and surgical problems].

A case is presented of an 8-year-old child reoperated on for recurrence of intracranial expansive lesion. Intraoperative cardiac arrest occurred and resuscitation was unsuccessful. The authors analysed the supposed causes of failures and laid stress on problems which may be encountered by the anaesthesiology-neurosurgical team. A number of physiopathological processes occurring here are presented in mathematical form.

Brain Neoplasms↗

PubMed1990

Bacterial proteins that mediate the association of a defined subset of T cell receptor:CD4 complexes with class II MHC.

We have examined the responses of cloned T cell lines and of normal T cells to staphylococcal enterotoxins A, B, and C1 (SEA, SEB, and SEC1). SEA, SEB, and SEC1 are all very potent mitogens for T cells in the presence of Ia+ APC. The minimal activating dose of all these SE varies from 1 to 100 ng/ml. As determined by mAb blocking of the responses of both normal T cells and cloned T cell lines, SEA required either the I-A or the I-E molecule on APC for stimulating T cells, whereas SEB required the I-E molecule predominantly over I-A molecule. The TCR:CD4 complex is also involved in the response to SE. The responses to SEB and SEC1 were inhibited by anti-V beta 8 antibody F23.1, whereas the response to SEA and to PHA was not affected by this antibody. Anti-CD4 effectively inhibited responses to all SE but not to PHA. The involvement of the TCR was also confirmed by flow microfluorimetry analysis of T cell blasts responding to SE and the responses of a panel of cloned T cell lines, both of which showed that V beta 8+ T cells preferentially responded to SEB, whereas V beta 8+ T cells failed to respond to SEA. By using fixed APC, it could be shown that processing is not required for the presentation of SE. Furthermore, pulsing experiments showed that SEB can bind to relevant sites on either B cells or T cells, whereas with conventional Ag only prepulsing of the APC has worked. In one case, SEB activates a cloned T cell line in the absence of APC, and this same clone also responds directly to anti-V beta 8 antibody. Thus, SEB appears to bring together V beta 8-expressing TCR with the I-E molecule, whereas SEA apparently has the same effect on TCR expressing different V beta with either the I-A or the I-E molecule, probably depending upon which TCR is bound. The close resemblance between T cell responses to SE and those to mixed-lymphocyte stimulating (Mls) locus suggests to us that a novel SE-like protein that binds both to class II MHC molecules on the APC surface and to V beta gene products on TCR could be the product of the Mls locus.

Animals↗

PubMed1990

Localization, distribution, and induction of xenobiotic-metabolizing enzymes and aryl hydrocarbon hydroxylase activity within lung.

The metabolism of xenobiotics within lung often leads to toxicity, although certain pulmonary cells are more readily damaged than others. This differential susceptibility can result from cell-specific differences in xenobiotic activation and detoxication. The localization and distribution of xenobiotic-metabolizing enzymes (cytochromes P-450, NADPH-cytochrome P-450 reductase, epoxide hydrolase, glutathione S-transferases, UDP-glucuronosyltransferases, and a sulfotransferase) and of aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity determined immunohistochemically and histochemically, respectively, within lung are discussed. Findings reveal that xenobiotics can be metabolized in situ, albeit to different extents, by bronchial epithelial cells, Clara and ciliated bronchiolar epithelial cells, and type II pneumocytes and other alveolar wall cells and that enzymes and activities are not necessarily induced uniformly among these cells.

Animals↗

PubMed1990

In situ localization and distribution of xenobiotic-activating enzymes and aryl hydrocarbon hydroxylase activity in lungs of untreated rats.

The present investigation was undertaken to more precisely establish where xenobiotics can be oxidatively metabolized and bioactivated within the lung. To accomplish this, antibodies raised against NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and cytochromes P-450 BNF-B, PB-B, and PCN-E (the major forms of cytochrome P-450 induced by beta-naphthoflavone, phenobarbital, and pregnenolone-16 alpha-carbonitrile, respectively) that had been purified to apparent homogeneity from rat liver microsomes were used to determine the localizations and distributions of these enzymes immunohistochemically at the light microscopic level within lungs of untreated rats. Additionally, the intrapulmonary sites at which benzo(alpha)pyrene undergoes hydroxylation were identified in situ by means of fluorescence histochemistry. Immunohistochemical staining for NADPH-cytochrome P-450 reductase and cytochromes P-450 BNF-B, PB-B, and PCN-E was detected in bronchial epithelial cells, both ciliated and nonciliated (Clara) bronchiolar epithelial cells, and type II pneumocytes as well as other cells in the alveolar wall. Results of microfluorometric analyses of the immunofluorescence staining intensities of bronchial epithelial cells, Clara cells, and type II pneumocytes demonstrated further that Clara cells bound the antibodies raised to NADPH-cytochrome P-450 reductase and cytochrome P-450 PB-B to significantly greater extents than did bronchial epithelial cells and type II pneumocytes. Thus, in lungs of untreated rats, Clara cells contain the greatest amounts of these two enzymes. In marked contrast, the antibodies directed against cytochromes P-450 BNF-B and PCN-E were each bound to similar extents by bronchial epithelial cells, Clara cells, and type II pneumocytes. In agreement with immunohistochemical observations on the intrapulmonary localizations of NADPH-cytochrome P-450 reductase and cytochromes P-450 BNF-B, PB-B, and PCN-E in untreated rats, benzo(alpha)pyrene was hydroxylated in situ by bronchial and bronchiolar epithelial cells and alveolar wall cells, especially type II pneumocytes. These immunohistochemical and histochemical findings, thus, demonstrate that bronchial epithelial cells, Clara and ciliated bronchiolar epithelial cells, and type II pneumocytes as well as other alveolar wall cells represent sites for the in vivo oxidative metabolism and bioactivation of xenobiotics in lungs of untreated rats.

Animals↗

PubMed1979

Immunohistochemical studies on electron transport proteins associated with cytochromes P-450 in steroidogenic tissues. II. Microsomal NADPH-cytochrome c reductase in the rat adrenal.

NADPH-cytochrome c reductase (NADPH : ferricytochrome oxido-reductase, EC 1.6.2.4), the flavoprotein which mediates the NADPH-dependent reduction of cytochromes P-450 in adrenocortical microsomes, has been localized immunohistochemically at the light microscopic level in rat adrenal glands. Localization was achieved through the use of sheep antiserum produced against purified, trypsin-solubilized rat hepatic microsomal NADPH-cytochrome c reductase in both an unlabeled antibody peroxidase-antiperoxidase technique and an indirect fluorescent antibody method. The sheep antibody to rat hepatic microsomal NADPH-cytochrome c reductase concomitantly inhibited the NADPH-cytochrome c reductase and progesterone 21-hydroxylase activities catalyzed by isolated rat adrenal microsomes. When sections of rat adrenal glands were exposed to the reductase antiserum in both immunohistochemical procedures, positive staining for NADPH-cytochrome c reductase was observed in parenchymal cells of the three cortical zones but not in medullary chromaffin cells. The intensity of staining, however, was found to differ among the three cortical zones, with the most intense staining being found in the zona fasciculata and the least in the zona glomerulosa. The intensity of staining was also found to differ among cells within the zona fasciculata. These immunohistochemical observations demonstrate that microsomal NADPH-cytochrome c reductase is not distributed uniformly throughout the rat adrenal cortex.

Adrenal Cortex↗