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Biomedical subjects

N Schechter

Publications and source records attributed to N Schechter.

At least 37 records · Page 2Linked to original sources
PubMed1994

Molecular cloning of gefiltin (ON1): serial expression of two new neurofilament mRNAs during optic nerve regeneration.

The goldfish visual pathway displays a remarkable capacity for continued development and plasticity. The intermediate filament proteins of this pathway do not match the intermediate filament protein composition of adult higher vertebrate neurons, which lack the capacity for growth and development. Using a goldfish retina lambda gt10 library we isolated cDNA clones representing the predominant goldfish optic nerve neurofilament protein, ON1. The mRNA for this protein is abundant in retinal ganglion cells, and its level increases slowly during optic nerve regeneration. The rate of ON1 mRNA accumulation after optic nerve crush was compared with that of plasticin, a previously described novel type III neurofilament from goldfish retinal ganglion cells. Plasticin mRNA is normally expressed at low steady state levels, but accumulates dramatically and rapidly, preceding gefiltin mRNA, in response to optic nerve crush. The predicted amino acid sequence for ON1 indicates that it is a novel intermediate filament protein. We have named it gefiltin, for goldfish eye intermediate filament protein. The serial expression of plasticin and gefiltin is discussed with respect to the diversity of neurofilament proteins during neurogenesis.

Amino Acid Sequence↗
PubMed1994

Lidocaine as a diluent for ceftriaxone in the treatment of gonorrhea. Does it reduce the pain of the injection?

OBJECTIVE: To compare the pain associated with ceftriaxone sodium injections by using two different diluents, ie, lidocaine hydrochloride and sterile water. DESIGN: Prospective study of adolescents who were culture positive for gonorrhea. Random selection of the diluent used for the intramuscular ceftriaxone therapy. SETTING: Urban, hospital-based adolescent medicine service. SUBJECTS: Thirty-nine adolescents and young adults, predominantly of black or Hispanic backgrounds, ranging in age between 14 and 23 years (mean age, 17.6 years; median age, 17 years), of whom 27 were females. METHODS: Pain predictions were elicited from the adolescents before treatment. Pain ratings were obtained at five time intervals after the injections. All ratings were obtained by using a visual analog scale. RESULTS: No pain prediction differences before the injection were noted between the two groups. Individual t tests showed significant pain differences between the two groups at the time after the injection and at 10- and 20-minute and 6-hour intervals. Repeated-measures analysis of variance models showed that the diluent effect on pain was significant. CONCLUSION: Lidocaine can reduce the amount of pain of an intramuscular injection of ceftriaxone when compared with sterile water as a diluent. These findings have implications not only for the treatment of gonorrhea but also for other situations where intramuscular injections utilizing a diluent may be necessary.

Adolescent↗
PubMed1994

Oral transmucosal fentanyl citrate for premedication of children undergoing laceration repair.

STUDY OBJECTIVE: To evaluate the safety and efficacy of two doses of oral transmucosal fentanyl citrate (OTFC) for premedication of children undergoing laceration repair. DESIGN: Prospective, randomized, nonblinded study. SETTING: Urban pediatric emergency department. PARTICIPANTS: Thirty children aged 2 to 8 years requiring laceration repair. INTERVENTIONS: Premedication with either 10 to 15 micrograms/kg or 15 to 20 micrograms/kg of OTFC. RESULTS: Activity score, vital signs, oxygen saturation, and pain scores were recorded before and after administration of OTFC. Activity scores decreased significantly 15 to 60 minutes after OTFC. The physician suturing the wound rated the child's sedation/pain control as excellent or good in 83% of patients. Vital signs changes were not clinically remarkable. Oxygen saturations remained at 95% or more except in one child who experienced a transient decrease to 91%. Adverse effects were not serious but included vomiting in 20% of the lower-dose group and 47% of the higher-dose group. There were no significant differences between dose groups for activity or pain score changes, physician assessment, discharge times, or adverse events. CONCLUSION: Both doses of OTFC reduced activity with comparable efficacy, with no serious vital signs changes. However, the higher-dose group had a greater number (P = NS) of adverse effects.

Administration, Oral↗
PubMed1994

Organization, sequence, and expression of a gene encoding goldfish neurofilament medium protein.

The goldfish visual pathway displays a remarkable capacity for continuous neurogenesis, plasticity, and regeneration. The intermediate filament protein composition of this system differs from that of higher vertebrates, which lack the capacity for continued nerve growth and development. In an effort to determine how intermediate filament proteins are regulated during nerve growth, we isolated and characterized cDNA and genomic clones representing the goldfish neurofilament medium (NF-M) protein. The tissue-specific expression of goldfish NF-M mRNA was analyzed by RNase protection assays and by in situ hybridization. The expression of goldfish NF-M is qualitatively the same as in other species. Although the intermediate filament protein composition of the goldfish visual pathway is unusual when compared with higher vertebrates, the goldfish NF-M protein is similar to higher vertebrate NF-M proteins. In addition, the organization of the goldfish NF-M gene is identical to the NF-M genes in all other vertebrate species. In contrast, the promoter region of the goldfish NF-M gene has several potential regulatory sequences that are not found in the promoter regions of higher vertebrate NF-M genes.

Amino Acid Sequence↗
PubMed1994

Cloning of multiple forms of goldfish vimentin: differential expression in CNS.

In efforts to determine the primary structure of intermediate filament proteins in the goldfish visual pathway, we isolated clones from a retinal lambda gt11 cDNA expression library that represent goldfish vimentin. We show that there are at least two forms of goldfish vimentin, designated as vimentin alpha and vimentin beta. RNase protection assays indicate that vimentin alpha mRNA is expressed in low amounts in retina, optic nerve, and brain and in higher amounts in spinal cord. In contrast, vimentin beta mRNA is expressed in low amounts in retina, optic nerve, brain, and spinal cord and in very high amounts in eye lens. Immunohistochemical studies show that in the optic nerve, vimentin alpha is mainly restricted to blood vessels, meninges, and septa. Light staining is observed with this antibody in an astrocytic glial pattern throughout the optic nerve. Two-dimensional gel analysis shows that all of these goldfish vimentins are low abundant components of optic nerve cytoskeletal preparations.

Amino Acid Sequence↗
PubMed1993

Homeobox genes are expressed in the retina and brain of adult goldfish.

The goldfish (Carassius auratus) visual pathway displays continuous growth and plasticity throughout life. Since homeobox genes are important transcriptional regulators in development, we searched for homeobox genes in the adult goldfish retina and brain. Using the PCR, we discovered a repertoire of homeobox sequences expressed in these tissues. In addition to isolating homeodomain sequences found in the vertebrate Hox gene clusters, a sequence identical to the chicken CHox7 homeodomain was characterized. Furthermore, a sequence with significant homologies to the Xenopus XIHbox8 and leech Htr-A2 homeodomains was identified, and these sequences may define an additional class of homeodomain. Finally, a sequence belonging to the paired class (prd) of homeodomains is reported. Homeobox gene expression in the adult goldfish retina and brain may be associated with the persistent developmental features of these tissues.

Amino Acid Sequence↗
PubMed1992

Crystallization, activity assay and preliminary X-ray diffraction analysis of the uncleaved form of the serpin antichymotrypsin.

Crystals of recombinant wild-type antichymotrypsin have been prepared by the method of vapor diffusion with polyethylene glycol 4000 as a precipitant at pH 5.7. Two crystal forms are observed. One form belongs to tetragonal space group P4(3)2(1)2 (or P4(1)2(1)2) and has unit cell dimensions a = b = 126 A, c = 243 A, with two molecules in the asymmetric unit. The other crystal form belongs to orthorhombic space group P2(1)2(1)2(1) and has unit cell parameters of a = 73 A, b = 78 A and c = 80 A, with one molecular in the asymmetric unit. Diffraction intensity measurements have been made on the tetragonal crystal form to a limiting resolution of 4.1 A, and reflections have been observed on X-ray still photographs to a limiting resolution of 2.5 A for the orthorhombic form. An activity assay of redissolved tetragonal form crystals indicates that the uncleaved, functional serpin has been crystallized.

Chymotrypsin↗
PubMed1992

Plasticin, a novel type III neurofilament protein from goldfish retina: increased expression during optic nerve regeneration.

The goldfish visual pathway displays a remarkable capacity for continued development and plasticity. The intermediate filament proteins in this pathway are unexpected and atypical, suggesting these proteins provide a structure that supports growth and plasticity. Using a goldfish retina lambda gt10 library, we have isolated a full-length cDNA clone that encodes a novel type III intermediate filament protein. The mRNA for this protein is located in retinal ganglion cells, and its level dramatically increases during optic nerve regeneration. The protein is transported into the optic nerve within the slow phase of axonal transport. We have named this protein plasticin because it was isolated from a neuronal pathway well known for its plasticity.

Amino Acid Sequence↗
PubMed1992

Cloning of a type I keratin from goldfish optic nerve: differential expression of keratins during regeneration.

We report the cDNA sequence and predicted amino acid sequence of a novel type I keratin, designated as GK50, and show that keratin expression in the goldfish optic nerve is highly complex. The GK50 protein is one of at least three type I keratins expressed in goldfish optic nerve based on both antibody reactivity and blot-binding to the type II keratin ON3. After optic nerve crush in situ hybridization shows a localized increase in GK50 mRNA expression in the crush zone. This is in contrast to ON3 mRNA which shows a localized increase that is limited to the proximal and distal margins of the crush zone, suggesting a diversity of keratin expression in different cell types of the goldfish optic nerve.

Amino Acid Sequence↗
PubMed1991

Rapid and specific conversion of precursor interleukin 1 beta (IL-1 beta) to an active IL-1 species by human mast cell chymase.

Secretory granules of human dermal mast cells contain a chymotrypsin-like serine proteinase called chymase. In this study, we demonstrate that the inactive cytokine, 31 kD interleukin 1 beta (IL-1 beta), can be converted rapidly to an 18 kD biologically active species by human mast cell chymase. The product formed is three amino acids longer at the amino terminus than the mature IL-1 beta produced by peripheral blood mononuclear cells and has comparable biological activity. Because chymase is a secretory granule constituent, it is likely to be released into the surrounding tissue when mast cells degranulate. It is also known that non-bone marrow derived cells resident in skin (keratinocytes, fibroblasts) produce but do not process 31 kD IL-1 beta. In this context, chymase may be a potent activator of locally produced 31 kD IL-1 beta. Mast cells lie in close apposition to blood vessels in dermis; therefore, chymase mediated conversion of 31 kD IL-1 beta might be expected to have a critical role in the initiation of the inflammatory response in skin.

Amino Acid Sequence↗
PubMed1991

Urticaria pigmentosa. Systemic evaluation and successful treatment with topical steroids.

Nine patients with adult-onset urticaria pigmentosa were studied for the incidence of extracutaneous mast cell involvement and the efficacy of potent topical corticosteroid therapy for cutaneous lesions. Seven of the nine patients had increased mast cells in the marrow biopsy specimens, and five patients had focal aggregates of mast cells. The bone scan was abnormal in one patient. Liver-spleen scans revealed a shift of colloid uptake from liver to spleen in four patients. No abnormal gastrointestinal tract roentgenograms were obtained. Urinary histamine metabolites correlated with nodular bone marrow involvement, but not with other parameters. Results of the psychoneurologic testing revealed significant deviation from the norm with a verbal memory deficit in all nine patients and abnormalities on the Minnesota Multiphasic Personality Inventory in four patients. All nine patients were treated with 0.05% betamethasone dipropionate ointment under occlusion over half of the body nightly for 6 weeks. Seven of nine patients treated responded with almost complete resolution of their lesions. Hypothalamic pituitary adrenal axis suppression was evaluated with intramuscular cosyntropin stimulation and metyrapone administration during treatment. Only two patients, both of whom used the medication improperly, developed transient abnormalities. Slow return of lesions was noted 6 months after completion of therapy. Remissions could be lengthened with single weekly applications of topical steroids. Systemic involvement is frequent in patients with cutaneous mast cell disease and it is best demonstrated by bone marrow biopsy. Mast cell lesions can be safely and effectively treated with topical steroids in motivated patients.

Administration, Topical↗
PubMed1991

Expression of neuronal intermediate filament proteins ON1 and ON2 during goldfish optic nerve regeneration: effect of tectal ablation.

Goldfish retinal explants were used to study optic tectum participation in the regulation of intermediate filament protein synthesis in retinal ganglion cells during optic nerve regeneration. Retinas were explanted at various times after removal of the contralateral optic tectum. The synthesis of the intermediate filament proteins ON1 and ON2 in the cultures was quantitated by labeling with [35S]methionine, followed by two-dimensional gel electrophoresis, autoradiography, and densitometry. Neuritic growth from the explants was quantitated based on fiber length and density. In retinal explants placed in culture after 23 days of optic nerve regeneration, the synthesis of ON1 and ON2 was reduced when the tectum had been ablated. In contrast, synthesis of these proteins in explants placed in culture at an earlier stage of regeneration was not affected by tectal ablation. At all time points tested, neuritic outgrowth from retinal explants was stimulated by tectal ablation. These findings indicate that the synthesis of the ON1 and ON2 intermediate filament proteins during regeneration is not directly regulated by axonal volume. Further, our findings suggest that interaction between growing axons and tectum is important for sustained expression of these proteins during the later stages of optic nerve regeneration.

Animals↗
PubMed1991

Minimal sensitization and excellent renal allograft outcome following donor-specific blood transfusion with a short course of cyclosporine.

UNLABELLED: A new protocol of donor-specific blood transfusion under cyclosporine coverage was developed and examined for immunologic consequences and clinical efficacy in recipients of one- or zero-HLA-haplotype-matched renal allografts. Between 1985 and 1989, 75 recipients were transfused with 100 ml of stored whole blood at 1, 8, and 15 days of its storage from either one-HLA-haplotype-matched related donors (n = 65, 33 from their parents, 30 from siblings, and 2 from offspring) or from zero-HLA-haplotype-matched donors (n = 10, 7 from spouses and 3 from siblings). During DST, all recipients received cyclosporine, 6 mg/kg/day, starting a day before and finishing a week after DST (23 days). Recipients were monitored by donor-specific mixed lymphocyte culture responses before and after DST, and serially for antibodies by fluorescence activated cell sorter analysis and by standard complement-dependent lymphocytotoxicity assay. Following DST with CsA, only 3 of 75 patients (4%) were sensitized against the blood donor. This rate is considerably lower, albeit statistically not significantly, compared with the 10% rate found in 30 recipients who had received DST without CsA in our previous study. Repeat MLC studied one to two months after DST (the day before transplant) were significantly increased compared with pre-DST (stimulation index: mean +/- SEM; 10.3 +/- 1.4 to 15.8 +/- 2.8, P = 0.004, and relative response: 40.9 +/- 5.1% to 49.8 +/- 5.5%, P = 0.003). Since the stimulation index with controls did not change after DST (23.4 +/- 2.9 to 26.2 +/- 3.3), enhanced MLC responses appear to be donor-specific. The changes in MLC responses did not correlate with the number of blood transfusion received prior to DST, the number of rejection episodes, or graft outcome. Fifty-seven recipients underwent a kidney transplant from their one-HLA-haplotype-matched blood donors within two to three months after DST. All 10 recipients of zero-haplotype-matched donors were also successfully transplanted from their respective blood donors. The graft survival rates were at least 90% at two years in both groups. IN CONCLUSION: (1) 100 ml of stored whole-blood DST, three times at weekly intervals with a short course of CsA is minimally sensitizing but effective in enhancing graft survival; (2) this protocol could be used in donor-recipient pairs who do not share a haplotype; and (3) DST with CsA elicits augmentation of donor-specific MLC responses.

Adolescent↗
PubMed1990

A plasminogen activator is induced during goldfish optic nerve regeneration.

The use of purified piscine plasminogen in a chromogenic solution assay enabled us to detect plasminogen activator (PA) activity in crude homogenates of goldfish optic nerve following nerve injury. In contrast, no activity was detected in the homogenates of uninjured nerve. Under conditions allowing regeneration of the optic axons (optic nerve crush), PA activity peaked 8 days after crush, and decreased to undetectable levels by 60 days. Under conditions allowing only degeneration of the axons (enucleation), the activity peaked at 8 days but decreased more rapidly. Casein zymography of samples after fractionation in SDS-PAGE showed that PA activity migrated as a doublet at Mr = 60-65 kd. Using this assay, activity was also observed in uninjured control nerves. This plasminogen-dependent activity migrated as three bands of higher molecular weight (Mr = 75, 95 and 120 kd) and was undetectable in solution assays of unfractionated extracts, suggesting complex formation with an inhibitor(s). Fibrin overlay assay of retinal explants and isolated primary cells in culture suggest that the goldfish PA is associated with the glial cells of the goldfish visual pathway.

Animals↗
PubMed1990

Keratin 8 of simple epithelia is expressed in glia of the goldfish nervous system.

The intermediate filament protein composition in glial cells of goldfish optic nerve differs from that found in glial cells of the goldfish spinal cord and brain. Brain and spinal cord glial cells contain glial fibrillary acidic protein (GFAP), whereas glial cells in the optic nerve contain ON3. The ON3 protein of the goldfish optic nerve was recently identified as the goldfish equivalent to the mammalian type II keratin 8 protein. In addition to the ON3 protein, the goldfish optic nerve also contains a 48-kDa protein. Immunoblotting experiments suggest that this protein is equivalent to the mammalian type I keratin 18 protein, which typically pairs with keratin 8 to form filaments. We show that these proteins are not specific to the optic nerve. The ON3 and 48-kDa proteins of the goldfish optic nerve share common antigenic properties with the predominant keratin pair expressed in the goldfish liver. These proteins are also expressed at low levels in the goldfish brain and spinal cord. In addition RNase protection assays and Northern blots indicate that the mRNA for the ON3 protein in optic nerve is identical to the message found in other goldfish tissues. The expression of ON3 was also examined in cultured glial cells from goldfish spinal cord and optic nerve and cultured fibroblast cells. Analysis of intermediate filament protein expression in cultured glial cells taken from goldfish spinal cord demonstrated the absence of GFAP in these cells and the expression of ON3. This protein was also the predominant intermediate filament protein of cultured optic nerve glial cells and fibroblasts. The differences in the expression of intermediate filament proteins in mammals and lower vertebrates are discussed. In addition, we discuss how the expression of a simple epithelial keratin pair in glial cells of the goldfish optic nerve may be associated with this system's capacity for continuous growth and regeneration.

Animals↗
PubMed1990

Neuronal intermediate filament expression during neurite outgrowth from explanted goldfish retina: effect of retinoic acid.

Regulation of the goldfish neuronal intermediate filament proteins ON1 and ON2 was investigated in a retinal explant system. The synthesis of these proteins in explanted retina decreased with increasing time in culture, despite continuing neurite outgrowth. Thus, ON1/ON2 neurofilament expression is regulated independently from neurite outgrowth. During regeneration of the goldfish optic nerve in vivo, the expression of these proteins increased during the later phase of the process, when growing axons make contact with the optic tectum. The declining synthesis of ON1 and ON2 during neurite outgrowth in culture suggests that factors extrinsic to the retina are necessary to support synthesis of these proteins. Treating retinal explants with retinoic acid stimulated the synthesis of the ON1/ON2 proteins in a dose-dependent manner. This stimulation was effective during a period of declining synthesis of the ON1/ON2 proteins, restoring their synthesis towards initial levels of expression. These results show that retinoic acid serves as a modulator of neurofilament expression in this in vitro model of nerve regeneration.

Animals↗
PubMed1989

A type II keratin is expressed in glial cells of the goldfish visual pathway.

The predominant intermediate filament proteins of the goldfish visual pathway consist of neuronal and non-neuronal isoelectric variants (58 kd). We have isolated a cDNA clone for the glial intermediate filament protein (ON3) from an optic nerve expression library. The predicted amino acid sequence of this clone reveals that it codes for a type II keratin representing the goldfish equivalent of mammalian keratin K8. K8 has been shown to be associated with embryogenesis and development. Unlike the mammalian visual system, the goldfish visual pathway displays a remarkable capacity for functional regeneration. The expression of K8, a protein not usually expressed in glial cells but shown to be associated with development, in the goldfish optic nerve may be involved with the processes of growth and regeneration in the goldfish visual pathway.

Amino Acid Sequence↗