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Biomedical subjects

J Martin

Publications and source records attributed to J Martin.

At least 505 records · Page 28Linked to original sources
PubMed1994

Identification and independent regulation of human mesangial cell metalloproteinases.

Mesangial cells are known to secrete metalloproteinases that are capable of degrading the constituents of the GBM, and hence are potentially involved not only in the regular maintenance of the ECM components in the glomerulus, but also of contributing to any damage to these components that occurs in disease states. In this report we positively identify by Northern blotting the neutral proteinase that is constitutively secreted by the human mesangial cell (HMC) as gelatinase A (MMP2). Stimulation of HMC gelatinase by IL-1 beta or PMA causes an increase in the total amount of gelatinolytic activity secreted. On examination, however, this increased activity is shown, both by immunoreactivity and by PCR to be due to the induction of the higher molecular weight form of gelatinase, gelatinase B (MMP9), while the amount of gelatinase A remained unaffected. In addition antigen and messenger RNA have been identified for both the specific inhibitors of metalloproteinases TIMP-1 and TIMP-2. The appearance of the larger inducible gelatinase with similar substrate specificity implies that the regular turnover of matrix components may be due to the constitutively released gelatinase A while in pathological situations the inducible gelatinase B becomes predominant. The synthesis and secretion of TIMP-1 and TIMP-2 indicates that the mesangial cell is capable of controlling the activity of its own secreted enzymes.

Base Sequence↗
PubMed1994

Modification of interpersonal psychotherapy with depressed adolescents (IPT-A): phase I and II studies.

OBJECTIVE: To test the acceptability and efficacy of interpersonal psychotherapy for depressed adolescents (IPT-A). METHOD: In phase I, therapeutic methods were explored and refined in a small sample of depressed adolescents (n = 5). In phase II, 14 depressed adolescents entered a 12-week open clinical trial of IPT-A; after independent evaluation. Subjects were assessed using a semistructured diagnostic interview, self-report, and clinician-administered instruments, at six time points: evaluation week, and weeks 0, 2, 4, 8, and 12. RESULTS: In phase I, treatment was modified to meet the needs of an adolescent population and was standardized in a treatment manual. The results of phase II indicated a significant decrease in adolescents' depressive symptomatology and symptoms of psychological and physical distress, as well as a significant improvement in functioning over the course of treatment. At termination, none of the subjects met DSM-III-R criteria for any depressive disorder. CONCLUSIONS: IPT-A appears to be a promising therapy for depressed adolescents. However, because of the limitations of the current study, a larger randomized controlled clinical trial is still needed to test its efficacy.

Adolescent↗
PubMed1994

The impact of home visits on enrollment patterns in pregnancy-related services among low-income women.

Medicaid now reimburses for care-coordination services for pregnant women in about half of the states. This care-coordination project targeted low-income pregnant women in two Indianapolis neighborhoods that historically have had high black-infant mortality rates. The service provided home visits by teams of workers including registered nurses, social workers, and indigenous community health workers. This retrospective descriptive study evaluated the impact of the home visits on enrollment in pregnancy-related services. Data were collected from the care-coordination records of 381 participants who delivered infants between July 1, 1990, and January 1, 1992. The proportion of participants enrolled in prenatal care, the Special Supplemental Food Program for Women, Infants and Children (WIC), Medicaid, and Food Stamps increased significantly following admission to care coordination. The majority of participants who enrolled in prenatal care and WIC, after admission to care coordination, did so within one month of admission. Home visits were effective in stimulating enrollment in pregnancy-related services. Further studies need to be done to evaluate the impact of home visits on pregnancy outcomes as well as their cost-effectiveness.

Adolescent↗
PubMed1994

Evidence of subtype-specific antibodies to antigenic epitopes in the NS5 region of hepatitis C virus in the circulation of patients with chronic hepatitis C.

The antigenicity of the NS5 region of type 1 hepatitis C virus (HCV) was investigated by epitope mapping of the region spanning amino acids 2530 to 2723 of the HCV polyprotein. Six antigenic regions were recognized by anti-HCV positive sera from individuals with chronic hepatitis C in a modified enzyme-linked immunosorbent assay with synthetic oligopeptides. Five of these regions demonstrated intra-type 1 sequence variations defining subtype 1a and 1b HCV sequences. The region between amino acids 2623 and 2634 allowed testing of subtype-specific anti-NS5 antibodies; serological reactivity to subtypes 1a and 1b was observed in 27 and 61%, respectively, of 150 cases with chronic hepatitis C. Simultaneous reactivity to subtypes 1a and 1b was found in 23% of the patients. Detection of subtype-specific anti-NS5 antibody correlated in more than 80% of the cases with the HCV genotype (subtypes 1a and 1b) analyzed by PCR amplification of the NS5 sequence. These data provide evidence of the existence of a subtype-specific anti-NS5 response in the circulation of patients with chronic hepatitis C.

Adolescent↗
PubMed1994

A nuclear encoded tRNA of Trypanosoma brucei is imported into mitochondria.

The mitochondrial genome of trypanosomes, unlike that of most other eukaryotes, does not appear to encode any tRNAs. Therefore, mitochondrial tRNAs must be either imported into the organelle or created through a novel mitochondrial process, such as RNA editing. Trypanosomal tRNA(Tyr), whose gene contains an 11-nucleotide intron, is present in both the cytosol and the mitochondrion and is encoded by a single-copy nuclear gene. By site-directed mutagenesis, point mutations were introduced into this tRNA gene, and the mutated gene was reintroduced into the trypanosomal nuclear genome by DNA transfection. Expression of the mutant tRNA led to the accumulation of unspliced tRNA(Tyr) (A. Schneider, K. P. McNally, and N. Agabian, J. Biol. Chem. 268:21868-21874, 1993). Cell fractionation revealed that a significant portion of the unspliced mutant tRNA(Tyr) was recovered in the mitochondrial fraction and was resistant to micrococcal nuclease treatment in the intact organelle. Expression of the nuclear integrated, mutated tRNA gene and recovery of its gene product in the mitochondrial fraction directly demonstrated import. In vitro experiments showed that the unspliced mutant tRNA(Tyr), in contrast to the spliced wild-type form, was no longer a substrate for the cognate aminoacyl synthetase. The presence of uncharged tRNA in the mitochondria demonstrated that aminoacylation was not coupled to import.

Animals↗
PubMed1994

Acute tamponade alters subendo- and subepicardial pressure-flow relations differently during vasodilation.

Instantaneous diastolic left coronary artery pressure-flow relations (PFR) shift during acute tamponade as pressure surrounding the heart increases. Coronary pressure at zero flow (Pf = 0) on the linear portion of the PFR is the weighted mean of the different myocardial waterfall pressures, the distribution of which varies across the left ventricular wall during diastole. However, instantaneous PFR measured in large epicardial coronary arteries cannot be used to estimate Pf = 0 in the different myocardial tissue layers. During coronary vasodilatation in a capacitance-free model, myocardial PFR differs from subendocardium to subepicardium. Therefore, we studied the effects of acute tamponade during maximal pharmacology induced coronary vasodilatation on myocardial PFR in in situ anesthetized dogs. Tamponade reduced cardiac output, aortic pressure, and coronary blood flow. Results demonstrate that different mechanisms influence distribution of myocardial blood flow during tamponade. Subepicardial vascular resistance is unchanged and the extrapolated Pf = 0 is increased, thereby shifting PFR to a higher intercept on the pressure axis. Subendocardial vascular resistance is increased while the extrapolated Pf = 0 remains unchanged. Results indicate that in the setting of acute tamponade with coronary vasodilatation different mechanisms regulate the distribution of myocardial blood flow: in the subepicardium only outflow pressure increases, whereas in the subendocardium only vascular resistance increases.

Animals↗
PubMed1994

Proposed nomenclature for quantifying subdivisions of the bronchial wall.

There is increasing interest in the structural components of the airway wall because of the airway remodeling that is observed in conditions such as asthma and chronic obstructive pulmonary disease and because of their contribution to changes in airway mechanics. This interest has stimulated several groups to make morphometric measurements on airway cross sections, and their results have been reported using a variety of nomenclature. We propose the adoption of a standard system of nomenclature that is based on accepted terms for subdivisions of the airway wall and has been agreed to by several groups working in this field.

Bronchi↗
PubMed1994

Jealousy: a community study.

This study represents the first attempt to study sexual jealousy in a random community sample. Jealousy was reported by all subjects. Men, when jealous, were particularly concerned about the potential loss of the partner, whereas women were more concerned with the effects of infidelity on the quality of the relationship. Behaviours such as searching the partner's belongings or inspecting their clothes for signs of sexual activity correlated with unusually intense jealousy. Men tended to cope with jealousy by using denial and avoidance, whereas women were more likely to express their distress and to try to make themselves more attractive to their erring partner. Greater jealousy concerns were expressed by young men who had either married early or were now living without a partner. Heavy drinkers and those reporting more psychiatric symptoms were also more prone to jealousy. A clear correlation emerged between lowered self-esteem and increased jealousy, which was particularly marked in women, for whom robust self-esteem was virtually incompatible with high jealousy concerns. The study supported the prosaic notion that those who are satisfied with their romantic attachments are less prone to jealous suspicions. This study offers a starting point for the clinician seeking information about the experience of jealousy in the community.

Adaptation, Psychological↗
PubMed1994

Response of colonic smooth muscle from newborn and adult rabbits to electrical field stimulation.

Electrical field stimulation (EFS) of circular smooth muscle from the proximal and distal colon of adult rabbits elicits region-specific patterns of contraction and relaxation referred to as on and off responses. The present study examined EFS-mediated on and off responses in neonatal (3- to 5-d-old), juvenile (2-wk-old), and adult rabbits to determine whether colonic motility undergoes a period of postnatal maturation with respect to the pattern of contraction/relaxation that develops in response to stimulation of the enteric nervous system. Muscle strips from the proximal and distal colon were oriented parallel to the circular muscle layer and stimulated electrically (80 V;0.5-ms pulse width) for 10 s using platinum wire electrodes. Stimulus frequency varied between 1 and 64 Hz. EFS stimulation of circular smooth muscle from the proximal colon of neonatal, juvenile, and adult rabbits was characterized by the development of atropine-sensitive on-contractions. The frequency-response curves were similar for each age group. In the distal colon, EFS of circular smooth muscle from neonatal, juvenile, and adult rabbits produced on-relaxations and atropine-insensitive off-contractions. The frequency-response data for the off-contractions were similar for each age group. Although no age-related differences were observed with respect to the pattern of contractile response to EFS, the force of the proximal colon on contractions and the distal colon off-contractions increased as the animals matured. The results suggest that the pattern of colonic enteric neurotransmission is established early in the neonatal period and does not undergo any significant change during the postnatal period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Topology of the morphological domains of the chaperonin GroEL visualized by immuno-electron microscopy.

Electron microscopy of the tetradecameric double-ring complex of GroEL reveals a four-layered structure, indicating that the 58 kDa subunits are composed of two major morphological domains. We have used immuno-electron microscopy to assign these domains to the corresponding segments of the GroEL sequence. Upon chemical modification of GroEL with N-ethylmaleimide, protease treatment in the presence of ATP or ADP generates GroEL fragments of 15 kDa (N15; residues 1-141) and 40 kDa (C40; residues 153-531). As visualized by scanning transmission electron microscopy, affinity-purified antibodies directed against C40 recognize the outer layers, whereas antibodies against N15 interact with the equatorial portions of the GroEL double-ring. Thus, the two major domains of the subunits in the chaperonin complex are arranged in the order C40-N15:N15-C40. The single-ring chaperonin co-factor GroES interacts with the C40 domain while the ATP-binding site of GroEL is probably close to the junction between N15 and C40.

Antibodies↗
PubMed1994

[Traumatic emergencies and AIDS].

At the reception of traumatic casualties, the medical staff is exposed to a contact with blood and thus to the risk of H.I.V. contamination. The hollow needle used for taking blood simple or doing intravascular injections is the most dangerous instrument, especially in the period next to medical care. The prevention of these accidents, which must be a permanent, systematic concern, does not take any advantage from the knowledge of the serological status of the patients but essentially rests on the care workers continuous education and the use of safety equipment.

AIDS Serodiagnosis↗
PubMed1994

[Screening of hemoglobinopathies and molecular analysis of beta-thalassemia in Central Tunisia].

BACKGROUND: Previous investigations have permitted to locate 16 beta-thalassemic mutations in different samples of the Tunisian population. One of them (IVS I nt 2: T--G) had been found only in the central region of Tunisia. Our research was carried out in this part of the country to estimate the prevalence of this mutation and to establish a prenatal diagnosis using appropriate probes. POPULATION AND METHODS: One thousand one hundred and five blood samples taken from 1987 to 1990 from healthy blood donors and 346 samples taken from 1985 to 1992 from patients were analysed. Detection of hemoglobinopathies was carried out by means of specific hematological tests and different electrophoretic and chromatographic techniques. Mutations were detected by means of the usual techniques of molecular biology. RESULTS: Sickle cell anemia and beta-thalassemia were the most frequent in the samples studied. The molecular analysis carried out on eight patients native of the Essouassi-El-Djem region point out that all these patients carry the same point mutation (IVS I nt 2: T-G) detected for the first time in 1988 in a patient native of the same region. One of these patients, aged 43, who did not suffer from anemia and did not show the usual symptoms of beta O thalassemia, had one hemolytic attack at the age of 17. CONCLUSIONS: The high number of persons carrying Hb S and beta-thalassemia trait increase the risk of appearance of homozygous forms. The presence of the same mutation IVS I nt 2: (T-G) in all beta O-thalassemic patients from Essouassi-El Djem region may indicate that it may have its origin there. The heterogeneity of clinical phenotype of these patients shows the difficulty of establishing a unique strategy of prenatal diagnosis by DNA analysing which can be applied in all cases.

Anemia, Sickle Cell↗
PubMed1994

A channel from the subconscious. Understanding drawing interpretation.

1. Drawing interpretations need not be a wild, mystic speculation, but can be a rational way of gaining insight based on firm research. 2. Interpretations should be considered as suggestions open for change. 3. Interpretations can give important clues on how to engage a client in therapy. 4. Interpretations should be treated with care, and the client's confidentiality respected.

Art↗
PubMed1994

Hb Taybe (alpha 38 or 39 THR deleted): an alpha-globin defect, silent in the heterozygous state and producing severe hemolytic anemia in the homozygous.

Several alpha-chain hemoglobin variants have been described as responsible, in homozygous or compound heterozygous patients, for a chronic hemolytic disease that overlaps thalassemia and Heinz bodies hemolytic anemia phenotypes. These variants are present in trace amounts together with some Hb H in the lysate of the patients. In the asymptomatic heterozygous carriers, they are usually not detected by electrophoretic methods. Hb Taybe is an example of such an unstable and thalassemic alpha-hemoglobin variant. This hemoglobin was observed in a young Israeli Arab woman having suffered since birth from a severe and highly regenerative hemolytic anemia for which she was splenectomized at age sixteen. The structural abnormality was characterized by protein chemistry as the deletion of a threonine residue at position alpha 38 or 39 and assigned to the alpha 1 gene by selective DNA sequencing. This structural modification is localized in helix C, which is a highly conserved 3(10) helix participating in the alpha 1 beta 2 contact and close to the alpha 1 beta 1 interface. The propositus and two siblings, who were also anemic, were found to be homozygous for the molecular defect, although the abnormal Hb was not detected in the latters. Consanguinity in this family demonstrated the threshold effect in the clinical manifestations of such alpha-gene disorders since heterozygotes were clinically and biologically normal.

Adult↗