PubMed Health⌕ Search

Biomedical subjects

S Spector

Publications and source records attributed to S Spector.

At least 37 records · Page 2Linked to original sources
PubMed1999

Conformational analysis of peptide fragments derived from the peripheral subunit-binding domain from the pyruvate dehydrogenase multienzyme complex of Bacillus stearothermophilus: evidence for nonrandom structure in the unfolded state.

There is currently a great deal of interest in the early events in protein folding. Two issues that have generated particular interest are the nature of the unfolded state under native conditions and the role of local interactions in folding. Here, we report the results of a study of a set of peptides derived from a small two-helix protein, the peripheral subunit-binding domain of the pyruvate dehydrogenase multienzyme complex. Five peptides of overlapping sequence were prepared, including sequences corresponding to each of the helices and to the region connecting them. The peptides were characterized by CD and, where possible, nmr. A peptide corresponding to the second helix is between 12 and 17% helical at neutral pH. CD also indicates a lower percentage of helical structure in the peptide corresponding to the first alpha-helix, although the values of the alpha-proton chemical shifts suggest some preference for nonrandom structure. Peptides corresponding to the interhelical loop, which in the full domain contains two overlapping beta-turns and a 5-residue 3(10)-helix, are less structured. There is no significant change in the helicity of any of these peptides with pH. To test for fragment complementation, CD spectra of the two peptides derived from each helix and the long connecting peptide were compared to the spectra of each possible pair, as well as to a mixture containing all three. No increase in structure was observed. We complement our peptide studies by characterizing a point mutant, D34V, which disrupts a critical hydrogen bonding network. This mutant is unable to fold and provides a useful model of the denatured state. The mutant is between 9 and 16% helical as judged by CD. The modest amount of helical structure formed in some of the peptide fragments and in the point mutant suggests that the denatured state of the peripheral subunit binding domain is not completely unstructured. This may contribute to the very rapid folding observed for the intact protein.

Amino Acid Sequence↗
PubMed1999

Ideal pharmacotherapy for allergic rhinitis.

The characteristics of the "ideal" pharmacotherapeutic agent for managing the symptoms of seasonal allergic rhinitis and the advantages and disadvantages of the pharmacotherapeutic agents that are currently available are reviewed. Decongestants, mast cell stabilizers, anticholinergics, intranasal steroids, and oral antihistamines and their place in the therapeutic armamentarium of the clinician are discussed.

Drug Administration Schedule↗
PubMed1999

Onset and duration of action of levocabastine nasal spray in atopic patients under nasal challenge conditions.

BACKGROUND: Although prior studies have documented the rapid onset of action of topical intranasal levocabastine (LEV), little is known about its duration of action under nasal challenge conditions. OBJECTIVES: We sought to assess the onset and duration of action of escalating doses of LEV nasal spray by using a nasal allergen challenge (NAC) model. METHODS: Eighteen asymptomatic subjects with histories of seasonal allergic rhinitis were enrolled into a randomized, single-blind, placebo-controlled, dose-ranging crossover study. Each patient was randomly assigned to receive single doses of placebo and intranasal LEV 0.1, 0.2, and 0.4 mg during 2 parts of the study. In part 1 (onset of action), NAC consisted of a single dose of allergen administered 5 minutes after study drug treatment. In part 2 (duration of action), NAC consisted of increasing doses of allergen administered 0.5, 6, 12, and 24 hours on separate days after study drug treatment. Nasal symptom scores (NSSs) and nasal peak expiratory flow rates were measured after NAC in both phases of the study. Blood samples for plasma LEV concentrations were drawn after each NAC. RESULTS: In part 1, NSSs were significantly lower after the administration of LEV 0.1, 0.2, and 0.4 mg compared with placebo (P <.05). In part 2, NSSs were significantly lower after LEV doses of 0.2 and 0.4 mg compared with placebo at 0.5, 6, 12, and 24 hours after treatment (P <.05). The mean provocative dose of allergen required to elicit a positive nasal reaction was increased after LEV doses of 0.2 and 0.4 mg at 0.5, 6, and 12 hours after treatment. Nasal peak expiratory flow rates demonstrated no significant differences between LEV and placebo for any doses at any time points. Mean plasma LEV concentrations were low (range, 0 to 3. 7 ng/mL) after all doses and did not correlate with drug efficacy. CONCLUSIONS: Single intranasal LEV doses of 0.1, 0.2, and 0.4 mg significantly reduced the severity of the immediate nasal response to allergen when administered 5 minutes before NAC. This protective effect against NAC continued to be present 24 hours after administration of LEV doses of 0.2 and 0.4 mg. Efficacy in blocking the reaction to NAC did not correlate with plasma LEV levels, suggesting that the inhibitory effect was due largely to topical rather than systemic effects.

Administration, Intranasal↗
PubMed1999

Reduction in seizure frequency following a short-term group intervention for adults with epilepsy.

A preliminary investigation of the efficacy of a group intervention combining a range of psychological approaches and techniques for seizure management in adults with poorly controlled epilepsy. An uncontrolled AB group design was employed. Seven adults with intractable seizures took part in 8, weekly group sessions which included providing information, employed cognitive-behavioural techniques and addressed emotional difficulties. Weekly seizure logs were kept by participants during the intervention and the following 3 months. Five questionnaires were administered before and after the intervention and at 2-months follow-up to provide an indication of psychosocial well-being. Seizure frequency and scores on the questionnaires were used as outcome measures. There was a significant reduction in seizure frequency in the group, which persisted at follow-up. There were no significant changes on any of the questionnaires. The results suggest that a group-based intervention incorporating a range of psychological techniques may be effective for improving seizure control. The link between seizure reduction and psychological and psychosocial well-being needs further investigation.

Adaptation, Psychological↗
PubMed1998

Cooperative folding of a protein mini domain: the peripheral subunit-binding domain of the pyruvate dehydrogenase multienzyme complex.

The peripheral subunit-binding domain from the dihydrolipoamide acetyltransferase (E2) component of the pyruvate dehydrogenase multienzyme complex from Bacillus stearothermophilus is stably folded, despite its short sequence of only 43 amino acid residues. A 41 residue peptide derived from this domain, psbd41, undergoes a cooperative thermal unfolding transition with a tm of 54 degrees C. This three-helix protein is monomeric as judged by ultracentrifugation and concentration-dependent CD measurements. Peptides corresponding to the individual helices are largely unstructured both alone and in combination, indicating that the unusual stability of this protein does not arise solely from unusually stable alpha-helices. Chemical denaturation by guanidine hydrochloride is also cooperative with a delta GH2O of 3.1 kcal mol-1 at pH 8.0 and 25 degrees C. The chemical denaturation is broad with an m-value of 760 cal mol-1 M-1. psbd41 contains a buried aspartate residue at position 34 that may provide stability and specificity to the fold. A mutant peptide, psbd41Asn was synthesized in which the buried aspartate residue was mutated to asparagine. This peptide still folds cooperatively and it is monomeric, but is much less thermostable than the wild-type with a tm of only 31 degrees C. Chemical denaturations at 4 degrees C give an m-value of 740 cal mol-1 M-1, similar to the wild-type, but the stability delta GH2O is only 1.4 kcal mol-1. Both the wild-type and the mutant unfold at extremes of pH, but at 4 degrees C psbd41Asn is folded over a narrower pH range than the wild-type. Although the mutant unfolds cooperatively by thermal and by chemical denaturation, its NMR spectrum is significantly broader than that of the wild-type and it binds ANS. These results show that Asp34 is vital for the stability and specificity of this structure, the second smallest natural sequence known to fold in the absence of disulfide bonds or metal or ligand-binding sites.

Amino Acid Sequence↗
PubMed1998

Effects of the immunostimulant, levamisole, on opiate withdrawal and levels of endogenous opiate alkaloids and monoamine neurotransmitters in rat brain.

This report present evidence that the immunostimulant drug levamisole, (-)-(S)-2,3,5,6-tetrahydro-6-phenylimidazo[2,1-b] thiazole monohydrochloride, produced a significant elevation of endogeneous morphine and codeine levels in brain regions and peripheral organs and attenuated the effects of naltrexone-induced withdrawal in morphine-addicted rats. Levamisole also significantly altered the metabolism of norepinephrine, dopamine, and serotonin in specific brain regions. These results suggest that levamisole's attenuation of opiate withdrawal may be related to its ability to increase endogeneous opiate alkaloid levels and/or to alter central monoaminergic function. Levamisole does not have significant affinity for opiate receptors. These results raise the intriguing possibility that agents such as levamisole, which elevate the levels of the endogenous opiate alkaloids, might be useful for treating narcotic withdrawal. The mechanism for the immunostimulatory properties of agents such as levamisole and muramyl dipeptide (MDP) have not been established. We suggest that the ability of MDP and levamisole to increase endogenous opiate alkaloids may be related to their immunostimulatory properties.

Adjuvants, Immunologic↗
PubMed1998

Prevalence of sensitization to aeroallergens in California patients with respiratory allergy. Allergy Skin Test Project Team.

BACKGROUND: The number of allergy skin tests required to evaluate patients with respiratory allergy has recently been challenged by the managed care community. OBJECTIVES: The purpose of this study was to determine which aeroallergens are prevalent in patients with respiratory allergy (allergic rhinitis and bronchial asthma) in California. METHODS: Utilizing aeroallergens thought to be relevant from recent aerobiologic and botanic data, 141 allergic and 17 asymptomatic control subjects were tested for the prevalence of 103 allergens. A standardized prick puncture technique and standardized interpretation of wheal/flare responses were utilized using the same lot of allergen for 13 allergy practices distributed throughout California. Frequency curves based on prevalence were established to determine the number of tests required to give up to 90% of positive responses for tree, weed and grass pollen, mold spores, and miscellaneous allergens which included house dust mite, cat, dog, and cockroach allergens. RESULTS: Positive responses in allergic subjects for grasses ranged from 46% to 54%, for weeds 19% to 37%, and for trees 10% to 42%. For molds the range was from 11% to 22%. The response rate for Dermatophagoides pteronyssinus was 53%, for Dermatophagoides farinae 42%, for cat pelt 39% and cat hair 37%, for cockroach 23% and dog dander 19%. Asymptomatic control subjects responded to only 4% of all allergens tested. Ninety percent of all positive tests required three miscellaneous allergens (house dust mite, cat, and cockroach), 9 molds, 2 grasses, 16 weeds, and 27 trees for a total of 57 allergens (56% of total tested). There was no clear relationship between locale and specific allergen response, probably related to the limited number of subjects tested and variability within the same geographic region. Several seldom tested tree and weed allergens showed a higher prevalence rate than several commonly tested for allergens. CONCLUSIONS: This preliminary study suggests that approximately 57 aeroalleroens might be adequate to detect 90% of all positive responses in patients with respiratory allergy in California. This study was limited by subject number and variability between study sites. It is hoped a standardized model can be developed from this pilot study to definitively determine which aeroallergens are relevant in the United States.

Adult↗
PubMed1998

Joint Task Force Algorithm and Annotations for Diagnosis and Management of Rhinitis.

The algorithm and text annotations in this document are intended to assist clinical decision making about patients who present with symptoms of rhinitis. This document complements the Executive Summary of Joint Task Force Practice Parameters for Diagnosis and Management of Rhinitis (Ann Allergy, Asthma, Immunol 1998; 81:463-468) and Diagnosis and Management of Rhinitis: Complete Guidelines of the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology (Ann Allergy, Asthma, Immunol 1998;81:478-578). The Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology is co-sponsored by the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology and the Joint Council of Allergy, Asthma and Immunology.

Algorithms↗
PubMed1998

Diagnosis and management of rhinitis: complete guidelines of the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology. American Academy of Allergy, Asthma, and Immunology.

This document contains complete guidelines for diagnosis and management of rhinitis developed by the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology, representing the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology and the Joint Council on Allergy, Asthma and Immunology. The guidelines are comprehensive and begin with statements on clinical characteristics and diagnosis of different forms of rhinitis (allergic, non-allergic, occupational rhinitis, hormonal rhinitis [pregnancy and hypothyroidism], drug-induced rhinitis, rhinitis from food ingestion), and other conditions that may be confused with rhinitis. Recommendations on patient evaluation discuss appropriate use of history, physical examination, and diagnostic testing, as well as unproven or inappropriate techniques that should not be used. Parameters on management include use of environmental control measures, pharmacologic therapy including recently introduced therapies and allergen immunotherapy. Because of the risks to patients and society from sedation and performance impairment caused by first generation antihistamines, second generation antihistamines that reduce or eliminate these side effects should usually be considered before first generation antihistamines for the treatment of allergic rhinitis. The document emphasizes the importance of rhinitis management for comorbid conditions (asthma, sinusitis, otitis media). Guidelines are also presented on special considerations in patients subsets (children, the elderly, pregnancy, athletes and patients with rhinitis medicamentosa); and when consultation with an allergist-immunologist should be considered.

Diagnosis, Differential↗
PubMed1997

Endogenous codeine and morphine in anorexia and bulimia nervosa.

The endogenous plasma alkaloids codeine and morphine were shown to be elevated in patients with anorexia nervosa and bulimia nervosa compared to control subjects. The role of these opioids in the pathophysiology of these eating disorders is discussed in relation to an auto-addiction opioid model. This model proposes that endogenous opioids are released during an initial period of dieting and reinforce a state of starvation dependence [1,2].

Adolescent↗
PubMed1996

Role of endogenous morphine in the attenuation of opiate withdrawal syndrome by N-acetylmuramyl-L-alanine-D-isoglutamine (MDP).

Opiates, long considered the prototypical addictive drug, cause the phenomenon of tolerance and physical dependence following chronic administration. Although many factors promote the addictive state, our studies have focused on the role of endogenous morphine in modifying physical dependence. Mammalian tissues contain morphine and codeine and have the capacity to synthesize these alkaloids. The present report shows that N-acetylmuramyl-L-alanine-D-isoglutamine (MDP), which elevates the endogenous opiate alkaloids in various brain regions and peripheral tissues, can attenuate the withdrawal syndrome of morphine-addicted rats.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1996

Bronchial inhalation challenge procedures with allergens and other bronchoconstrictor substances.

Antigen inhalation challenges nowadays are most commonly used as an investigative tool to better understand the pathophysiology of asthma and possible blocking effects of immunotherapy. However, they also serve to better define the role of specific allergens in asthma, and as a possible substitution for skin tests when they cannot be performed. Of particular interest in the literature has been the late asthmatic response and the increase in so-called nonspecific reactivity that follows. When a new pharmaceutical agent is studied, its ability to block both the late phase and subsequent hyperreactivity is presumptive evidence for effectiveness. The more commonly employed challenges with bronchoconstrictive substances, such as methacholine and histamine, have been used to assess atypical asthma, better define occupational asthma and a way to quantitate hyperreactive airways disease. Other bronchoconstrictive agents that have been employed include acetylcholine, carbamylcholine, serotonin, prostaglandins and leukotrienes. Since any bronchoconstrictor agent has a potential for making a patient uncomfortable due to the induced bronchoconstriction, necessary equipment for anaphylaxis should be available and trained personnel should be aware of possible adverse reactions which can occur uncommonly.

Allergens↗
PubMed1995

Volume changes of the molten globule transitions of horse heart ferricytochrome c: a thermodynamic cycle.

Volume changes among the unfolded (U), native (N), and molten globule (MG) conformations of horse heart ferricytochrome c have been measured. U to N (pH 2 to pH 7) was determined in the absence of added salt to be -136 +/- 5 mL/mol protein. U to MG (pH 2, no added salt to pH 2, 0.5 M KCl) yielded + 100 +/- 6 mL/mol. MG to N was broken into two steps, N to NClx at pH 7 by addition of buffered KCl to buffered protein lacking added salt (NClx = N interacting with an unknown number, X, of chloride ions), and MG to NClx by jumping MG at pH 2 in 0.5 M KCl to pH7 at the same salt concentration. The delta V of N to NClx was -30.9 +/- 1.4 mL/mol protein, whereas MG to NClx entailed a delta V of -235 +/- 6 mL/mol. Within experimental error, the results add up to zero for a complete thermodynamic cycle. We believe this to be the first volumetric cycle to have been measured for the conformational transitions of a protein. The results are discussed in terms of hydration contributions from deprotonation of the protein, other hydration effects, and the formation and/or enlargement of packing defects in the protein's tertiary structure during the steps of folding.

Animals↗
PubMed1995

Possible role of endogenous morphine and codeine on growth regulation of lung tissue.

The literature indicates that morphine can inhibit the growth of both small cell and non small cell lung cancer cell lines and that nicotine can reverse this inhibition. In this report we present data showing that mammalian lung tissue contain the opiate alkaloids morphine and codeine and that these alkaloids are also to be found in normal lung cell lines. However, analysis of both small cell and non small cell lung cancer cells indicate that they do not contain these opiate alkaloids endogenously. If morphine exerts an inhibitory effect on proliferation of these cells it is interesting that the lung cancer cell lines lack the opiate alkaloids endogenously. Our studies also present data indicating that the circulating levels of morphine and codeine are elevated in smokers as compared to non smokers which we hypothesize to reflect the invocation of a compensatory mechanism.

Adult↗
PubMed1995

Esmarch closure of laparotomy incisions in unstable trauma patients.

Fascial closure after laparotomy may be time-consuming and extremely difficult, especially in the setting of massive bowel edema. In the trauma patient with deteriorating hemodynamic status, hypothermia, or worsening hypoxia, expeditious abdominal wall closure is essential to facilitate rapid transport to the intensive care unit for further stabilization. With the increasing utilization of the abbreviated laparotomy in unstable trauma patients, innovative techniques for speedy fascial closure must be evaluated. We developed the Esmarch closure--a simple, rapid method for closing the abdominal wall at the end of abbreviated laparotomies.

Abdomen↗
PubMed1994

Anabolic effect of human growth hormone: management of inherited disorders of catabolic pathways.

The effects of growth hormone treatment and dietary alanine supplementation, individually and in combination, were studied in five patients with organic acidemias. Three patients had propionic acidemia, one had 3-hydroxyisobutyric acidemia, and one had a defect in isoleucine metabolism. Two patients with propionic acidemia had decreased growth hormone secretion in response to provocative stimuli (intravenous L-arginine and oral levodopa or clonidine); the remaining subjects had sufficient growth hormone secretion. Three of four subjects in whom IGF1 was measured showed subnormal concentrations at baseline (including two with normal growth hormone secretory responses). All patients showed an increase in linear growth with growth hormone. In the four patients studied, all had a significant increase in nitrogen retention over baseline with alanine or growth hormone alone, or with the combination of growth hormone and alanine, with a much greater effect of growth hormone. Lean body mass and body fat composition tended to become normal with treatment. Protein tolerance increased, and when the patients' dietary protein intakes were increased between 20 and 60% they maintained positive nitrogen balance, without a significant increase in metabolite excretion. One patient with propionic acidemia expired during the time of the study, following a course of recurrent pancreatitis and an episode of acute basal ganglia infarction. All of the other subjects showed clinical improvement (decreased incidence of ketoacidotic episodes and decreased frequency of hospital admission and school absence) during treatment, and even the patient who expired remained metabolically stable up to and through the terminal event. We conclude that growth hormone may be of value in the management of patients with organic acidemia.

3-Hydroxybutyric Acid↗