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Biomedical subjects

M Kogan

Publications and source records attributed to M Kogan.

At least 19 recordsLinked to original sources
PubMed2006

Diffuse basal ganglia or thalamus hyperechogenicity in preterm infants.

OBJECTIVE: To determine the incidence and factors associated with diffuse basal ganglia or thalamus hyperechogenicity (BGTH) in preterm infants. STUDY DESIGN: (1) Review of serial neurosonograms among neonates with gestational age (GA) <34 weeks born at Weiler Hospital during a 21-month period; (2) Color Doppler flow imaging; (3) Case-control study using GA group-matched controls; and (4) Blind reading of CT scans or MRIs in patients with BGTH. RESULTS: Among 289 infants, 24 (8.3%) had diffuse BGTH. Color Doppler flow imaging was normal in nine patients. The incidence of diffuse BGTH was inversely related to GA (P<0.01). Logistic regression (n=96) showed that diffuse BGTH was significantly associated with requirement of high-frequency oscillation (HFO) (P=0.031), severe intraventricular hemorrhage (IVH) (P=0.004), hypotension requiring vasopressors (P=0.040), hypoglycemia (P=0.031) and male gender (P=0.014). Most patients with diffuse BGTH had normal basal ganglia and thalamus on CT/MRI, one had a hemorrhage, and one had an ischemic infarction. CONCLUSIONS: In our series, diffuse BGTH occurred in 8.3%, and was associated with factors similar to those previously reported. In contrast, several series have reported almost exclusively linear or punctuate hyperechoic foci, corresponding to hyperechogenicity of the lenticulostriate vessels. Our data provide further evidence to suggest that diffuse BGTH and hyperechogenicity of the lenticulostriate vessels are two different entities. Additional studies are required to determine the long-term significance of diffuse BGTH.

Basal Ganglia↗
PubMed2001

Distinct roles for two N-terminal cleaved domains in mitochondrial import of the yeast frataxin homolog, Yfh1p.

The yeast frataxin homolog (Yfh1p) participates in mitochondrial iron homeostasis. The phenotypic defects of the Delta yfh1 mutant include drastic accumulation of iron in mitochondria and slow growth. The Yfh1p precursor protein contains two N-terminal domains that are sequentially cleaved by the matrix processing peptidase on import into mitochondria, generating the mature protein. We have precisely mapped these two cleavage sites. Mutations blocking the first or the second cleavage of Yfh1p do not interfere with its in vitro import or with its ability to complement phenotypes of the Delta yfh1 mutant strain. Distinct roles have been ascertained for the two cleaved domains of Yfh1p. The first cleaved domain (domain I) is sufficient for in vitro mitochondrial import of a non-mitochondrial passenger protein. However, neither domain I nor other matrix-targeting signals alone can support efficient in vitro import of mature Yfh1p. The second cleaved domain (domain II) is required as a spacer between a targeting signal and mature Yfh1p. Likewise, when Yfh1p constructs lacking domain I or II are expressed in vivo, they fail to attain appreciable steady-state amounts in mitochondria and cannot complement phenotypes of the Delta yfh1 mutant.

Amino Acid Sequence↗
PubMed2001

Inhibition of HIV-2(ROD) replication in a lymphoblastoid cell line by the alpha1-antitrypsin Portland variant (alpha1-PDX) and the decRVKRcmk peptide: comparison with HIV-1(LAI).

We investigated the effects of alpha1-antitrypsine Portland variant (alpha1-PDX) and decanoylRVKRchloromethylketone (decRVKRcmk) on HIV-2(ROD) replication in the Jurkat lymphoblastoid cell line. To this end, cells were stably transfected with the alpha1-PDX (J-PDX) and used as targets for HIV-2(ROD) infection. Controls were prepared with the empty vector (J-pcDNA3). HIV-2(ROD) and HIV-1(LAI) replications were significantly inhibited and delayed in the presence of the alpha1-PDX protein. When decRVKRcmk was used at 35 microM, inhibition rates were 70-80% for HIV-2(ROD) and HIV-1(LAI), while total inhibition occurred at 70 microM. Control peptides consisting of decanoylRVKR and acetylYVADcmk had no effect. In the presence of the alpha1-PDX or the decRVKRcmk at 35 microM, the infectivity of HIV-2(ROD) and HIV-1(LAI) produced was 3-4-fold lower. Both molecules inhibited syncytium formation by HIV-2(ROD) and HIV-1(LAI) to a considerable extent. Finally, the inhibition of viral replication was correlated with the ability of the decRVKRcmk at 35 and 70 microM and of the alpha1-PDX, to inhibit the processing of envelope glycoprotein precursors. The alpha1-PDX protein and the decRVKRcmk peptide at 35 microM inhibited HIV-2 and HIV-1 to a similar level suggesting that identical or closely related endoproteases are involved in the maturation of their envelope glycoprotein precursors into surface and transmembrane glycoproteins. The significant inhibition observed with alpha1-PDX indicates that furin or furin-like endoproteases appear to play a major role in the maturation process.

Amino Acid Chloromethyl Ketones↗
PubMed1999

Yeast mitochondrial protein, Nfs1p, coordinately regulates iron-sulfur cluster proteins, cellular iron uptake, and iron distribution.

Nfs1p is the yeast homolog of the bacterial proteins NifS and IscS, enzymes that release sulfur from cysteine for iron-sulfur cluster assembly. Here we show that the yeast mitochondrial protein Nfs1p regulates cellular and mitochondrial iron homeostasis. A strain of Saccharomyces cerevisiae, MA14, with a missense NFS1 allele (I191S) was isolated in a screen for altered iron-dependent gene regulation. This mutant exhibited constitutive up-regulation of the genes of the cellular iron uptake system, mediated through effects on the Aft1p iron-regulatory protein. Iron accumulating in the mutant cells was retained in the mitochondrial matrix while, at the same time, iron-sulfur proteins were deficient. In this work, the yeast protein was localized to mitochondria, and the gene was shown to be essential for viability. Furthermore, Nfs1p in the MA14 mutant was found to be markedly decreased, suggesting that this low protein level produced the observed regulatory effects. This hypothesis was confirmed by experiments in which expression of wild-type Nfs1p from a regulated galactose-induced promoter was turned off, leading to recapitulation of the iron regulatory phenotypes characteristic of the MA14 mutant. These phenotypes include decreases in iron-sulfur protein activities coordinated with increases in cellular iron uptake and iron distribution to mitochondria.

Amino Acid Sequence↗
PubMed1999

RESPONSIVE-TO-ANTAGONIST1, a Menkes/Wilson disease-related copper transporter, is required for ethylene signaling in Arabidopsis.

Ethylene is an important regulator of plant growth. We identified an Arabidopsis mutant, responsive-to-antagonist1 (ran1), that shows ethylene phenotypes in response to treatment with trans-cyclooctene, a potent receptor antagonist. Genetic epistasis studies revealed an early requirement for RAN1 in the ethylene pathway. RAN1 was cloned and found to encode a protein with similarity to copper-transporting P-type ATPases, including the human Menkes/Wilson proteins and yeast Ccc2p. Expression of RAN1 complemented the defects of a ccc2delta mutant, demonstrating its function as a copper transporter. Transgenic CaMV 35S::RAN1 plants showed constitutive expression of ethylene responses, due to cosuppression of RAN1. These results provide an in planta demonstration that ethylene signaling requires copper and reveal that RAN1 acts by delivering copper to create functional hormone receptors.

Alkenes↗
PubMed1999

Nitroxide stable radical suppresses autoimmune uveitis in rats.

Free radicals have been implicated in the pathogenesis of experimental autoimmune uveoretinitis (EAU). Nitroxides are stable radicals with a superoxide-dismutase-mimicking activity, which exert an anti-inflammatory effect in various animal models of oxidative damage and inflammation, such as experimental colitis and head trauma. We examined the use of the SOD mimic nitroxide 4-hydroxy-2,2,6,6,-tetramethylpiperidine-1-N-oxyl (TPL) to suppress EAU. Adult male Lewis rats were immunized with 125 microg/rat synthetic human retinal S-Ag, emulsified with Freund's adjuvant. Intravenous pertussis toxin was simultaneously injected. Beginning on Day 6, rats were injected with a daily intraperitoneal dose of 35, 175 or 350 micromol/rat of the nitroxide TPL. Control rats received intraperitoneal normal saline. The animals were examined daily, and on the 19th day the eyes were enucleated. Aqueous protein concentrations and retinal lipid peroxidation product levels (ketodienes and conjugated dienes) were determined. Histological sections were stained and examined microscopically. TPL was found to penetrate the aqueous humor readily. Beginning on day 12, rats developed a severe pan-uveitis. Rats in the treatment group had a lower mean clinical and histological score than that of controls. Levels of aqueous humor protein, retinal conjugated diens and ketodiens were all significantly lower in the treatment group. This effect was more pronounced with the lower TPL concentration. We conclude that TPL reduces clinical, biochemical and histopathological severity of S-Ag induced EAU in Lewis rats. This effect is probably mediated by removal of superoxide radicals, but other mechanisms may also be involved.

Amino Acid Sequence↗
PubMed1999

Let's talk: patterns and correlates of social support among temporary employees.

The authors explored how temporary employees exchanged communications with supervisor, peers, and family and friends regarding positively job-related, negatively job-related, and non-job-related contents. The authors also examined roles of communication in coping with insecure job experiences. Survey results from 112 temporary employees working in various organizations provided evidence that communication contents were differentially related to work anxiety and life satisfaction for temporary employees. It was found that work anxiety increased when employees engaged in communication pertaining to negative job-related contents. Furthermore, the positive relationship between life satisfaction and positive communication with coworkers was observed only for the temporary employees who also had a permanent job. Implications for staffing temporary employees and suggestions for studying communication effects are discussed.

Adaptation, Psychological↗
PubMed1998

Integrated pest management: historical perspectives and contemporary developments.

Twenty five years after its first enunciation, IPM is recognized as one of the most robust constructs to arise in the agricultural sciences during the second half of the twentieth century. The history of IPM, however, can be traced back to the late 1800s when ecology was identified as the foundation for scientific plant protection. That history, since the advent of modern organosynthetic pesticides, acquired elements of drama, intrigue, jealousy, and controversy that mark the path of many great scientific or technological achievements. Evolution of IPM followed multiple paths in several countries and reached beyond the confines of entomological sciences. Time and space constraints, however, bias this review toward entomology, among the plant protection sciences, and give it an obvious US slant, despite the global impact of IPM.

Animals↗
PubMed1997

Variations of the flexor digitorum superficialis tendon of the little finger.

Seventy cadaveric hands were dissected to study variations of the flexor digitorum superficialis tendon (FDS) to the little finger. Anatomical variations were present in 13% of hands and 10% of the hands showed an anatomical variation that would preclude independent FDS function in the little finger. The distance of the decussation from the metacarpophalangeal joint was measured. A ratio of this distance to proximal phalangeal length was calculated. The ratio indicated that decussation position was independent of phalangeal size.

Cadaver↗
PubMed1996

Streaming conjunctiva.

BACKGROUND: Epithelial proliferation is linked with cell displacement. When a cell divides, one of its progeny replaces the dividing ancestor and the other is displaced into a more remote location that has to be vacated first by peripheral cells. As cells are neither pushed nor pulled in a mechanical sense, and since they do not move by their own means, this displacement is best regarded as streaming. The purpose of the present study was to measure epithelial cell streaming in adult rat conjunctiva. METHODS: Twenty-seven female adult rats were injected i.p. with 18.5 KBq [3H]-thymidine/g body weight, specific activity 185 GBq/mMol. Three rats were killed at different times up to 28 d. Eyes and eyelids were removed in one piece, cut along the pupillary-optic nerve line into 5-microns-thick sections, and prepared for autoradiography. In each eye, the entire upper conjunctiva extending from limbus to the palpebral muco-cutaneous junction was scanned with an ocular micrometer grid. The limbus served as point of origin. The x, y coordinate of each nucleus with two grains or more and its grain content were recorded. RESULTS: One hour after labeling, labeled cells were spread evenly along the basal layer. Cells of the upper layers were not labeled. As time passed by, labeled cells in the fornix became more abundant, while in the limbus and palpebral margin, their frequency declined. Labeled cells streamed from the limbus and palpebral muco-cutaneous junction to the fornix. Bulbar conjunctival epithelia streamed at a velocity of 13.2 microns/day. Epithelia in the palpebral conjunctiva streamed at a velocity of 11.8 microns/day. At the same time cells streamed from the basal layer to the epithelial surface at a velocity of 0.4 microns/day. Generation time was 3.9 days. CONCLUSIONS: Bulbar and palpebral conjunctivae are two independent cell kinetic systems that originate in two stem cell regions, one in the limbus and the other in the muco-cutaneous junction. Each system is made of two compartments, a progenitor where cells proliferate, and a compartment of non proliferating end cells. Progenitors created in the first, enter the second and turn into end cells. Ultimately they die in the fornix. The undetermined limbus stem cell generates two epithelial cell lines, a corneal and a conjunctival.

Animals↗
PubMed1996

A United States national reference for fetal growth.

OBJECTIVE: To develop a current national fetal growth curve that can be used as a common reference point by researchers to facilitate investigations of the predictors and consequences of small and large for gestational age delivery. METHODS: Single live births to United States resident mothers in 1991 (n = 3,134,879) were used for the development of this curve, which was compared with four previously published fetal growth curves. Techniques were developed to address cases with implausible birth weight-gestational age combinations and to smooth fetal growth curves across gestational age categories. RESULTS: In general, the previously published fetal growth curves underestimated the 1991 United States reference curve. This underestimation is most apparent during the latter weeks of gestation, approximately 33-38 weeks. CONCLUSION: Our findings indicate that the prevalence of fetal growth restriction (FGR) will vary markedly, depending on the fetal growth curve used. Furthermore, many previously published fetal growth curves no longer provide an up-to-date reference for describing the distribution of birth weight by gestational age and for determining FGR that is consistent with the most recent live birth data for the entire United States.

Embryonic and Fetal Development↗
PubMed1996

Pyomyoma after uterine instrumentation. A case report.

BACKGROUND: Since 1945, only 10 cases of pyomyoma have been described in the literature. Four were related to pregnancy but none to elective abortion or uterine instrumentation. CASE: A 32-year-old woman was admitted to the hospital with a history of lower abdominal pain, nausea, vomiting and low grade fever with a past medical history significant for uterine leiomyomata and a second-trimester elective abortion 10 weeks prior to admission. Pelvic sonography demonstrated an enlarged uterus with a mass consisting of cystic and solid components. Uterine curettage revealed blood clots and scanty endometrial tissue. After no improvement following antibiotic therapy and nondiagnostic uterine curettage, an exploratory laparotomy was performed. It revealed peritonitis with multiple pyomyomas draining purulent material. CONCLUSION: Although rarely reported, pyomyoma should be considered in the setting of a recent history of uterine instrumentation, signs of infection and a uterine myoma.

Abortion, Induced↗
PubMed1986

Elevation of thioridazine plasma levels by propranolol.

As part of a pilot study to assess the efficacy of propranolol in the treatment of aggression in psychiatric patients, drug interactions of propranolol with other agents were estimated by blood level monitoring. In the two patients taking a standard oral dose of thioridazine, the addition of propranolol caused a threefold and fivefold increase of plasma thioridazine levels, which placed them in a potentially toxic range. Although neither patient exhibited a toxic effect, these levels may be associated with an increased risk of thioridazine-induced irreversible pigmentary retinopathy, cardiac arrhythmias, and tardive dyskinesia. The authors suggest precautionary monitoring of thioridazine plasma and other relevant levels and clinical assessments when thioridazine and propranolol are used in combination.

Adult↗
PubMed1981

Lectin-induced inhibition of nerve growth factor binding by receptors of sympathetic ganglia.

Nerve growth factor (NGF) initiates a pleiotypic response in numerous tissues derived from the neural crest by binding to specific plasma membrane receptors. In sympathetic ganglia this receptor has been characterized as a highly asymmetric, minimally hydrophobic, intrinsic membrane protein with a molecular weight of 135,000 (Costrini et al., 1979b). To further characterize this moiety we assessed the effects of lectins on 125I-NGF specific binding to preparations of particulate and nonionic detergent-extracted microsomal receptors of rabbit superior cervical ganglia (SCG). Concanavalin A (Con A) and wheat germ agglutinin (WGA), but not soybean agglutinin or Ulex europaeus 1, induced a concentration-related, carbohydrate-specific decrease in 125I-NGF binding. Following Con A exposure, 125I-NGF specific decrease in 125I-NGF binding. Following Con A exposure, 125I-NGF specific binding to particulate SCG receptors was maximally reduced to 23% of control values. WGA similarly reduced NGF binding to particulate microsomal receptors to 37% of control values. Scatchard analysis of growth factor binding following Con A exposure indicated that this lectin effect was principally due to a sixfold reduction in maximum receptor affinity. Lectin-associated impairment of NGF binding was also demonstrated by using a Triton X-100 solubilized receptor preparation. These results provide evidence that the high-affinity-state NGF receptor of SCG is a glycoprotein containing N-acetylglucosamine and alpha-D-mannopyranoside residues. These residues are probably located in close proximity to the growth factor binding region of the NGF receptor.

Animals↗
PubMed1979

Physical properties of the detergent-extracted nerve growth factor receptor of sympathetic ganglia.

The nerve growth factor (NGF) receptor from microsomes of adult rabbit superior cervical ganglia has been solubilized with Triton X-100 and sodium deoxycholate. The physical properties of the detergent-extracted NGF receptor were assessed by Sepharose 6B chromatography and sucrose density gradient ultracentrifugation studies in H2O and D2O. The predominant form of the NGF receptor has a Stokes radius of 71 A, a partial specific volume of 0.74 ml/g, a sedimentation coefficient of 4.3 S, and a frictional ratio of 1.8. From these parameters, it can be calculated that the NGF receptor in Triton X-100 is a minimally hydrophobic, highly asymmetric, intrinsic membrane protein with a molecular weight of approximately 135,000. A form of the receptor with a sedimentation coefficient of 10.4 S was occasionally seen which appears to represent an aggregated form of the 4.3 S moiety.

Animals↗