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L M Kaplan

Publications and source records attributed to L M Kaplan.

At least 37 records · Page 2Linked to original sources
PubMed1990

Galanin-like immunoreactivity is influenced by estrogen in peripubertal and adult rats.

Galanin gene expression in the anterior pituitary is potently stimulated by estrogen in adult rats. To evaluate the influence of estrogen on galanin during the peripubertal period 30- to 32-day-old female rats were treated with pregnant mare serum gonadotropin (PMSG, 10 IU s.c., 10.00 h). Galanin-like immunoreactivity (galanin-LI) in hypothalamic and pituitary tissues was evaluated 1, 2 or 3 days after PMSG treatment between 17.00 and 19.00 h. The PMSG treatment stimulated 17 beta-estradiol secretion, which induced a midafternoon LH surge 2 days after the PMSG treatment. Concentrations of galanin-LI at the time of this LH surge were elevated 82% in the anterior pituitary and 58% in the hypothalamus (without the median eminence) when compared to saline-treated female rats. On the 3rd day after the PMSG injection, galanin-LI was increased 236% in the anterior pituitary, 88% in the neurointermediate lobe and 39% in the median eminence compared to saline-treated female rats. These changes in galanin-LI were not observed in similarly aged male rats or ovariectomized rats treated with PMSG. In adult male rats, daily injections with 17 beta-estradiol valerate (10 micrograms/daily s.c.) for 1 week increased galanin-LI in the median eminence and neurointermediate lobe to an extent similar to that seen in juvenile female rats following PMSG treatment. In contrast, the high serum levels of 17 beta-estradiol achieved after 17 beta-estradiol valerate treatment increased galanin-LI in the anterior pituitary 65-fold. These studies indicate that galanin-LI is influenced by estrogen in peripubertal and adult rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Specific alpha 1-adrenergic receptor subtypes modulate catecholamine-induced increases and decreases in ventricular automaticity.

Fifty percent of adult canine Purkinje fibers manifest a decrease in automaticity in response to alpha 1-adrenergic stimulation with 10(-10)-10(-8) M norepinephrine (NE), and 50% manifest an increase. In contrast, most neonatal Purkinje fibers show an increase in automaticity in response to these concentrations of NE. We studied the modulation of NE effects, using the subtype selective alpha 1-adrenergic antagonists chloroethylclonidine (CEC) and WB 4101. CEC selectively antagonized the decrease in automatically such that, in both age groups, all Purkinje fibers showed NE-induced increases in automaticity. In Purkinje fibers from dogs treated with pertussis toxin, NE no longer induced a CEC-sensitive decrease in automaticity. In contrast, WB 4101 selectively antagonized the NE-induced increase in automaticity in both age groups. In the presence of WB 4101, NE decreased automaticity uniformly in adult Purkinje fibers and tended to induce no change in automaticity in neonatal Purkinje fibers. In the presence of prazosin (10(-6) M) or combined CEC (10(-7) M) and WB 4101 (10(-7) M), no alpha-agonist-induced increase or decrease in rate was observed. Pretreatment of membranes from newborn and adult dog and rat ventricles with CEC resulted in a selective and irreversible inactivation of 25% of specific binding sites labeled with [125I]IBE2254. In cultured neonatal rat ventricular myocytes, exposure to CEC resulted in a 35% decrease in the density of specific binding sites labeled with [125I]IBE2254 but did not influence alpha-adrenergic stimulation of inositol phosphate accumulation. In contrast, WB 4101 inactivated NE-stimulated inositol phosphate accumulation. Our results suggest that 1) at least two distinct alpha 1-adrenergic receptor subtypes are present in neonatal and adult cardiac tissue, 2) the CEC-sensitive subtype is linked to a decrease in automaticity via a pertussis toxin-sensitive substrate, 3) the WB 4101-sensitive subtype is linked to an increase in automaticity (possibly via a mechanism related to phosphoinositide breakdown), and 4) although CEC- and WB 4101-sensitive alpha 1-adrenergic receptor subtypes are present in the neonate, only the WB 4101-sensitive subtype is expressed functionally to induce effects on ventricular automaticity.

Age Factors↗
PubMed1990

Estrogen increases galanin immunoreactivity in hyperplastic prolactin-secreting cells in Fisher 344 rats.

Galanin is a widely distributed regulatory peptide which modulates the pituitary secretion of PRL and GH. Estrogen administration strongly stimulates galanin gene expression in the rat anterior pituitary. In adult female Fischer 344 rats, estrogen also induces hyperplasia of lactotropes. We used immunocytochemical analysis to assess the effects of estrogen on galanin-like immunoreactivity (Gal-IR) in the rat pituitary and hypothalamus during sc diethylstilbestrol (DES) implantation and after its removal at 30 days. In the anterior pituitary, DES implantation increased the portion of Gal-IR-containing cells from less than 2% in the control rats to 18.3% after 3 days of DES and 36% after 30 days. These changes paralleled the lactotrope hyperplasia exhibited in response to DES exposure. Ten and 30 days after removal of the DES capsules, the percentage of Gal-IR-containing cells in the anterior pituitary decreased to 6.3% and 1.5%, respectively. Colocalization studies revealed that Gal-IR-containing cells were predominantly lactotropes. Immunoelectron microscopy demonstrated that Gal-IR was concentrated in the Golgi region of these hyperplastic lactotropes and suggests that little of the synthesized galanin is secreted. The distribution of Gal-IR in the hypothalamus, median eminence, and neurohypophysis was unaffected by DES treatment. These data demonstrate that galanin is synthesized by hyperplastic pituitary lactotropes of Fischer 344 rats and that peptide accumulation is dependent on the presence of circulating estrogens. In contrast, neuronal galanin synthesis in the hypothalamus does not appear to be regulated by estrogen.

Animals↗
PubMed1989

Alpha-1 adrenergic stimulation of 1,4,5-inositol trisphosphate formation in ventricular myocytes.

We demonstrated previously that alpha-1 adrenergic catecholamines modulate cardiac automaticity in a manner that is dependent upon the function of a pertussis toxin sensitive guanine nucleotide binding protein (G protein). Furthermore, we demonstrated that alpha-1 adrenergic receptor stimulation promotes the accumulation of inositol monophosphate (IP1). In the present study we used high-pressure liquid chromatography to resolve individual inositol phosphate isomers formed in norepinephrine-stimulated cultured rat ventricular myocytes. Norepinephrine stimulated a rapid, transient increase in 1,4,5-inositol trisphosphate (1,4,5-IP3) which was followed by slower, sustained increases in 1,3,4-IP3, inositol bisphosphate (IP2) and IP1. IP1 was composed of two major isomers with retention times characteristic of 1-IP1 and 4-IP1. 4-IP1 was the predominant IP1 isomer formed during stimulation with norepinephrine suggesting that the polyphosphoinositides rather than phosphatidylinositol are the principal targets of norepinephrine-stimulated phospholipase C activity in the heart. This was confirmed in studies performed on myocyte membranes which demonstrated proportionately greater IP2 and IP3 (relative to IP1) accumulation in response to norepinephrine. G protein regulation of alpha-1 adrenergic-dependent inositol phospholipid hydrolysis also was examined. In myocyte membranes, guanosine-5'-0-(3-thiotriphosphate) induced the accumulation of IP2 and IP3 and was required for the stimulatory effect of norepinephrine. This response was not impaired after pretreatment with pertussis toxin. These results indicate that the myocyte alpha-1 adrenergic receptor is coupled to a polyphosphoinositide-specific phospholipase C by a pertussis toxin insensitive G protein and suggest that under certain conditions IP3 may serve an important role in alpha-1 adrenergic modulation of cardiac function.

Animals↗
PubMed1988

Galanin is an estrogen-inducible, secretory product of the rat anterior pituitary.

Galanin is a peptide widely distributed throughout vertebrate central and peripheral nervous systems. Although its precise physiologic role is unknown, it can stimulate the pituitary secretion of prolactin and growth hormone. We examined the control of rat galanin (rGal) gene expression in the anterior pituitary using RNA blot and in situ hybridization analyses and using specific RIA. Pituitaries of normal male and ovariectomized female rats contained little detectable rGal mRNA. Treatment of these animals with 17 beta-estradiol increased pituitary rGal mRNA up to 4000-fold. These increases depended on time and dose of estrogen administration and correlated with up to 50-fold increases in pituitary galanin-like immunoreactivity. Galanin-like immunoreactivity was detectable in the plasma of estrogen-treated animals. Pituitary levels of rGal mRNA in female rats varied greater than 30-fold during the estrous cycle, with a peak on estrus and a nadir on diestrus. Estrogen-induced rGal gene expression was also observed in transplantable MtTW15 prolactin- and growth hormone-containing tumors but not in neuronal tissues expressing this gene. These data demonstrate that rGal is a secreted product of rat anterior pituitary cells, where its gene expression is strongly affected by physiologic levels of circulating estrogen.

Animals↗
PubMed1988

Tissue-specific expression of the rat galanin gene.

We have isolated and characterized cDNAs encoding rat galanin from a cDNA library prepared from rat hypothalamic tissue. Analysis of these clones reveals that rat galanin is synthesized initially as part of a 124-amino acid precursor that includes a signal peptide, galanin (29 amino acids), and a 60-amino acid galanin mRNA-associated peptide. In the precursor, galanin includes a C-terminal glycine and is flanked on each side by dibasic tryptic cleavage sites. The deduced amino acid sequence of rat galanin is 90% similar to porcine galanin, with all three amino acid differences in the C-terminal heptapeptide. The predicted galanin mRNA-associated peptide includes a 35-amino acid sequence that is 78% similar to the previously reported porcine analogue. This sequence is set off by a single basic tryptic cleavage site and includes a 17-amino acid region that is nearly identical to the porcine counterpart. The high interspecies conservation suggests a biological role for this putative peptide. Blot hybridization analysis using rat genomic DNA is consistent with a single galanin-encoding gene. RNA blot analysis of total RNA prepared from rat tissues reveals a single band of hybridizing mRNA that is approximately 900 nucleotides long. Rat galanin mRNA is located predominantly in the central nervous system and gastrointestinal tract. Highest central nervous system concentrations are found in the hypothalamus, with lower levels in the cortex and brainstem. Gastrointestinal rat galanin mRNA is most abundant in the duodenum, with progressively lower concentrations in the stomach, small intestine, and colon.

Amino Acid Sequence↗
PubMed1987

Spontaneous rupture of ureter.

A patient with spontaneous ureteral rupture in the absence of obstruction or calculus disease is presented. In addition to ureteral rupture this patient also had a penile squamous cell carcinoma and infected inguinal lymph nodes. A review of the literature discloses that all reported cases with spontaneous rupture of the ureter had an underlying process leading to that rupture. It is considered, therefore, that rupture of the ureter should be designated as "traumatic" or "nontraumatic." The term "spontaneous," implying a primary event, is a misnomer. No such case has been reported occurring in an otherwise healthy individual.

Carcinoma, Squamous Cell↗
PubMed1987

The effect of verapamil in reducing the severity of acute tubular necrosis in canine renal autotransplants.

Calcium channel blockade has been shown to prevent warm renal ischemic damage. The ability of verapamil to decrease the severity of acute tubular necrosis (ATN) after 24-hr cold storage and autotransplantation was studied in a randomized paired study of 12 dogs. Experimental animals pretreated with intraarterial verapamil and flushing of the harvested kidney with cold intracellular solution containing verapamil demonstrated significantly (P less than .05) greater renal function preservation over their matched controls. A subsequent nonpaired study of 6 dogs treated only with flushing of the harvested kidney with perfusate containing verapamil demonstrated no significant preservation advantage over controls. We conclude that verapamil, administered prior to the ischemic event, can enhance the protective effect of hypothermia and decrease the severity of ATN in ischemically injured kidneys.

Acute Kidney Injury↗
PubMed1986

Association between abdominal wall defects and cryptorchidism.

To determine whether intra-abdominal pressure may have a role in the process of testicular descent in man, we reviewed retrospectively the records of all male infants who presented during a 10-year period with severe abdominal wall defects, such as gastroschisis (28), omphalocele (29) and umbilical hernia (53), and calculated the incidence of cryptorchidism in these patients. The incidence of cryptorchidism at birth and at 1 year after birth was 18 and 15 per cent, respectively, in patients with gastroschisis, 52 and 33 per cent, respectively, in those with omphalocele, and 6 and 6 per cent, respectively, in those with umbilical hernia. For all 3 disorders the incidence of cryptorchidism was higher than in documented historical controls. From these data we conclude that in male infants there is an association between these 3 abdominal wall defects and cryptorchidism. The demonstration that intra-abdominal pressure is lowered significantly by these abdominal wall defects would suggest a possible role for intra-abdominal pressure in the process of testicular descent in man.

Abdominal Muscles↗
PubMed1986

Increasing handwashing compliance with more accessible sinks.

The frequency of handwashing in two intensive care units (ICUs) was observed. Handwashing after direct contact with patients or their support equipment was recorded. The ratio of beds to sinks was 1:1 in the medical ICU and 4:1 in the surgical ICU. Surveillance of physicians, nurses, and other personnel demonstrated a greater frequency of handwashing by nurses (63%) compared with physicians (19%) and other personnel (25%). The nurses in the unit with one sink per bed had a significantly greater number of handwashes (76%) than those in the unit with fewer sinks (51%).

Cooperative Behavior↗
PubMed1984

Metastases to the adrenal glands and the development of Addison's disease.

Metastases to the adrenal glands are common in patients with cancer but symptomatic Addison's disease is rarely noted in this population. The development of body computerized tomography (CT) allows the diagnosis of adrenal metastases to be made more readily antemortem. From 1980 to 1981, 19% (4/21) of patients at the Massachusetts General Hospital who had metastatic cancer and who were noted to have enlarged adrenal glands on CT also had or developed symptomatic adrenal insufficiency. The case histories of 8 patients with Addison's disease and one patient with adrenal hemorrhage on the basis of metastatic infiltration are reviewed. Since adrenal insufficiency may develop abruptly in this group of patients, it is suggested that prophylactic maintenance glucocorticoid therapy be initiated as soon as the diagnosis of adrenal metastases is made.

Addison Disease↗
PubMed1983

Q-T prolongation and torsades de pointes ventricular tachycardia produced by the tetracyclic antidepressant agent maprotiline.

Tricyclic antidepressant drugs such as imipramine and desipramine have long been known to produce cardiovascular side effects including sinus tachycardia, prolongation of the P-R, QRS, and Q-T intervals, and decreased T-wave amplitude. Life-threatening ventricular ectopic activity has occurred after tricyclic drug overdose. Recently, maprotiline (Ludiomil), a tetracyclic anthracene-derivative antidepressant, has become available for the treatment of affective disorders. It appears as effective as the tricyclic drugs in relieving unipolar depression. Although several studies have reported a low incidence of cardiovascular side effects, others show little difference between the tetracyclic and tricyclic drugs. This report describes a patient in whom maprotiline treatment caused Q-T prolongation and life-threatening torsades de pointes ventricular tachycardia (VT).

Aged↗
PubMed1979

Complementation of the temperature-sensitive defect in H5ts125 adenovirus DNA replication in vitro.

Soluble extracts of adenovirus-infected HeLa cell nuclei support DNA replication on exogenous adenovirus DNA templates. Conditions of synthesis using both wild-type and temperature-sensitive extracts have been defined. Nuclear extracts prepared from cells permissively infected with the adenovirus mutant H5ts125 expressed the temperature-sensitive phenotype and could be inactivated at 37 degrees C in vitro. These extracts were completely complemented by the addition of wild-type adenovirus DNA binding protein but not by H5ts125 DNA binding protein. Enhancement by binding protein in the mutant extracts represents replication, as demonstrated by the production of full-sized products and orderly chain elongation originating, as in vivo, at both ends of the linear DNA. Replicative synthesis required the 5'-terminal protein bound covalently to template DNA and could be inhibited by denaturation of this 55,000-dalton protein. Various inhibitors of eukaryotic DNA polymerases, such as aphidicolin and 2',3'-dideoxythymidine triphosphate, inhibited replication of exogenous adenovirus templates in this system as they do in previously reported systems that only elongate endogenous replicating intermediates.

Adenoviruses, Human↗
PubMed1977

Replication of adenovirus type 2 DNA in vitro.

A soluble replication system that synthesizes full-sized adenovirus DNA molecules has been developed. The extraction of infected HeLa nuclei solubilizes approximately 25% of the viral replicating DNA and leaves the HeLa chromatin associated with the insoluble nuclear material. Both the extracted viral DNA and the DNA product synthesized in vitro are intact and identical to the adenovirus DNA or its replicating intermediates produced in whole infected cells. The direction of elongation and the termini of replication of progeny DNA in vitro are essentially identical to those observed in vivo. Nuclear extract replication is dependent on Mg2+ and the four deoxyribonucleoside triphosphates and partially stimulated by ATP.

Adenoviridae↗