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Biomedical subjects

N Lin

Publications and source records attributed to N Lin.

At least 37 records · Page 2Linked to original sources
PubMed2000

Age, the stress process, and physical distress: the role of distal stressors.

OBJECTIVES: This article examines the nature of distal stressors over a 15-year period and the extent to which they contribute to the explanation of additional variation in the life stress model. METHODS: The study uses data collected from a community sample of adults to test specific hypotheses. RESULTS: Findings show that (a) distal stressors significantly increase variance explained in physical symptoms and maintain a direct effect on physical symptoms, (b) recent stressors mediate the effects of distal stressors on distress, and (c) social resources have direct and mediating effects on physical distress. Variations exist for different age groups or life stages. DISCUSSION: The implications of the findings are discussed in the context of life course, theoretical issues of temporality, types of stressors, and the role of social resources. The major conclusion is that there are multiple pathways to distress that differ for different stages in the life course.

Age Factors↗
PubMed2000

A meta-analysis of prospective trials comparing percutaneous and surgical tracheostomy in critically ill patients.

STUDY OBJECTIVES: Tracheostomy is one of the most commonly performed procedures in the patient receiving long-term mechanical ventilation. While percutaneous dilational tracheostomy (PDT) is becoming increasingly utilized as an alternative to conventional surgical tracheostomy, most literature evaluating these two techniques is neither prospective nor controlled. We performed a meta-analysis of available prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients to more fully understand the relative benefits and risks of these two procedures in this population. DESIGN: Meta-analysis using Mantel-Haenszel fixed effect model. INTERVENTIONS: We performed searches of MEDLINE, Current Contents, Best Evidence, Cochrane, and HealthSTAR databases from 1985 to present to identify prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients. After establishing clinical and statistical homogeneity (Q: statistic), studies were analyzed by a Mantel-Haenszel fixed effect model. For each clinical end point examined, PDT and surgical tracheostomy were compared by calculating either absolute differences or odds ratios (ORs) with 95% confidence intervals (CIs) for continuous or discrete variables, respectively. MEASUREMENTS AND RESULTS: We pooled data from five studies (236 patients) satisfying our search criteria to analyze eight clinical end points. Operative time was shorter for PDT than surgical tracheostomy: absolute difference with 95% CI, 9. 84 min (7.83 to 10.85 min). There was no difference comparing PDT and surgical tracheostomy with respect to overall operative complication rates: OR with 95% CI, 0.732 (0.05 to 9.37). However, relative to surgical tracheostomy, PDT was associated with less perioperative bleeding (OR with 95% CI, 0.14 [0.02 to 0.39]), a lower overall postoperative complication rate (OR with 95% CI, 0.14 [0.07 to 0.29]), as well as a lower postoperative incidence of bleeding (OR with 95% CI, 0.39 [0.17 to 0.88]), and stomal infection (OR with 95% CI, 0.02 [0.01 to 0.07]). No difference was identified in days intubated prior to tracheostomy (absolute difference with 95% CI, 0.16 days [- 0.9 to 1.22 days]), overall procedure-related complications (OR with 95% CI, 0.73 [0.06 to 9.37]), or death (OR with 95% CI, 0.63 [0.18 to 2.20]) comparing these two techniques. CONCLUSIONS: Despite its popularity, there are currently only a limited number of small studies prospectively evaluating PDT and surgical tracheostomy. Our meta-analysis of these studies suggests potential advantages of PDT relative to surgical tracheostomy, including ease of performance, and lower incidence of peristomal bleeding and postoperative infection. If confirmed by additional, adequately powered prospective trials, these findings support PDT as the procedure of choice for the establishment of elective tracheostomy in the appropriately selected critically ill patient.

Blood Loss, Surgical↗
PubMed2000

Immediate post-abortal insertion of the frameless GyneFix IUD: initial experience in China.

The promising results obtained with the frameless GyneFix IUD for interval insertion led to the belief that the technology could be useful for immediate post-abortal application to reduce the number of induced and repeat abortions. IUDs have many advantages and the method is acceptable and safe. However, side effects and expulsion of conventional IUDs remain a problem. In an attempt to minimise these problems, the frameless GyneFix IUD was developed. Clinical studies conducted over the past 14 years have shown that the principles on which the device is based are valid. An increasing bulk of clinical evidence shows that the design characteristics of the device (fixed, frameless and flexible) are responsible for the low expulsion, high effectiveness, and high tolerance and continuation rates.1 Experience with the frameless IUD in China since 1989 confirms the international experience with the device. The present communication is a second report from China with the GyneFix IUD. In the present study the GyneFix IUD is inserted immediately following termination of pregnancy of less than 10 weeks amenorrhea. It is concluded that immediate post-abortal insertion of the frameless IUD is easy and safe, and appears to be as reliable and as effective as when it is inserted at interval. The GyneFix IUD could, therefore, constitute an important new option in the prevention of abortion.

Abortion, Induced↗
PubMed1999

Interrelationship of genetic and environmental influences on conduct disorder and alcohol and marijuana dependence symptoms.

Data from the Vietnam Era Twin (VET) Registry were analyzed to explore the degree to which the same genetic and environmental factors contribute to childhood conduct disorder symptoms and to alcohol and marijuana dependence symptoms. Data on conduct disorder and alcohol and marijuana dependence were obtained from administration of the Diagnostic Interview Schedule to 1,856 monozygotic and 1,479 dizygotic male-male twin pair members of the VET Registry. Multivariate genetic models were compared to determine the genetic and environmental influences common and or specific to all three phenotypes. A full model that allowed for common genetic and environmental influences to all three phenotypes gave a good fit to the data, but the best fitting reduced model did not allow for a genetic influence on conduct disorder symptoms. Under the best fitting reduced model, genes explained 44.7% of the variance in risk for alcohol dependence symptoms. The genetic liability for symptoms of marijuana dependence was due to a 36.3% specific contribution and a 7.6% contribution from genes common with alcohol dependence symptoms. Family environmental contributions common to all three phenotypes explained 46.7%, 11.9%, and 21.3% of variance in risk for symptoms of conduct disorder, alcohol dependence, and marijuana dependence, respectively. Common family environmental factors contribute to risk of conduct disorder symptoms and alcohol and marijuana dependence symptoms. Common genetic influences contribute to risk of symptoms of alcohol dependence and marijuana dependence. While our findings suggest genes do not contribute to co-morbid conduct disorder symptoms, comparisons with other twin studies suggest that the role of genes in risk for conduct disorder remains uncertain.

Adult↗
PubMed1999

Translocation (4;15)(p16;q24): a novel reciprocal translocation in a patient with BCR/ABL negative myeloproliferative syndrome progressing to blastic phase.

A patient with BCR/ABL negative myeloproliferative syndrome with a 46,XY,del(3)(q21), t(4;15)(p16;q24) karyotype is described. Fluorescence in situ hybridization performed with chromosomes 4 and 15 painting probes confirmed a novel reciprocal (4;15) translocation. The absence of crkl tyrosine phosphorylation, no activation of the abl kinase as measured by autophosphorylation, and a normal-size abl transcript suggest an alternative mechanism for leukemogenesis to that operative in Ph positive BCR/ABL positive chronic myeloid leukemia. A number of genes potentially relevant to tumorigenesis, some involving the ras signaling pathway, map to the 4p16 and 15q24 chromosome regions.

Acute-Phase Reaction↗
PubMed1999

Age differences in the effects of network composition on psychological distress.

The main goal of this research is to better understand age differences in the effects of social networks on mental health. Using a social network approach to revise the convoy of social support model (Kahn and Antonucci, 1980), we examine specifically how two aspects of social support networks (kin composition and convoy dimensions) influence psychological distress for older and younger samples (18-59 and 60+). We hypothesize that kin composition will influence distress in general but especially for the younger sample, while two competing hypotheses for the convoy of social support model are tested. Using data from a three-wave panel health study, structural equation models (LISREL 8.20) indicate that a greater proportion of kin in the perceived support network and the presence of family members in the inner circle of the convoy significantly reduce distress, primarily for the younger sample. Implications for the convoy model are discussed.

Adolescent↗
PubMed1999

Social support and depressed mood: a structural analysis.

Current literature on social support identifies social structure as a source of distress. However, past efforts tend to operationalize structure in terms of demographic characteristics. The present paper argues that structure should be conceived of as participation and involvement in community and social relations. Structure may include community ties, social networks and intimate ties. We hypothesize that the three elements represent the outer layer (belongingness), the intermediary layer (bonding), and the inner layer (binding) of social relations and should exhibit differentiated effects on mental health. We further hypothesize that these structural elements, in sequence, provide functional (i.e., instrumental-expressive, perceived-received, and routine-non-routine) supports which, in turn, prevent or protect against distress. Using data from the 1993-1994 Albany survey, we construct measures for elements of structural and functional support to test the relationship between the two as well as their effects on depression. Results confirm that elements of structural support, as predicted, differentially affect functional supports, and that the elements of both structural and functional supports exert direct effects on depression. Further, structural supports also exert indirect effects on depression, mediated by functional supports.

Adult↗
PubMed1998

RPE secreted proteins and antibody influence photoreceptor cell survival and maturation.

Proteins in media conditioned by retinal pigment epithelial cells (RPE-CM) and an antibody against these proteins (RPE-SP) were tested for their respective effects on rat retinal development in vitro and in vivo. Proteins of RPE-CM were separated in denaturing gels and evaluated by Western blot analysis. Retinal explants from postnatal day 2 (P2) rats were cultured in RPE-CM only or CM diluted with the RPE-SP antibody and, after 7 days, the explants were dissociated into single cells that were immunostained for opsin. RPE-CM or antibody was also injected into the vitreous of postnatal day 7 (P7) Long-Evans rats and analyzed 7 and 21 days later. Electrophoretic analysis of RPE-CM predominantly showed 60-70 kDa proteins; when these proteins were probed with RPE-SP antibody by Western blot, immunoreactive proteins were restricted to this narrow molecular weight range. In P2 retinal explant cultures supplemented with RPE-CM, long ganglion cell-like neurites were detected in 3 days. This activity was nullified in explant cultures grown in RPE-CM titrated with antibody, and these explants appeared to degenerate within 5 days. Over 80% of dissociated retinal cells from explants 7 days after treatment with RPE-CM expressed opsin, compared to only 20% of cells from explants grown in defined medium or serum. Retinas of P14 rats injected intravitreally with RPE-CM at P7 had increased numbers of ectopic photoreceptor cells within the inner nuclear layer when compared to retinas of sham-injected eyes. In contrast, retinas of eyes injected intravitreally with RPE-SP antibody exhibited shorter outer (OS) and inner (IS) segments and thinner outer nuclear (ONL) and outer plexiform (OPL) layers than retinas of sham-injected eyes. In conclusion, proteins in RPE-CM appeared to accelerate and maximize the development of rat photoreceptor cells in vitro, while intravitreal injections of its antibody caused an apparent retardation of outer segment maturation. These results suggest that a protein(s) secreted by RPE plays a key role in normal retinal development, particularly in photoreceptor cell survival and outer segment maturation.

Animals↗
PubMed1998

Co-occurrence of abuse of different drugs in men: the role of drug-specific and shared vulnerabilities.

BACKGROUND: Previous research has demonstrated genetic and environmental influences on abuse of individual substances, but there is less known about how these factors may influence the co-occurrence of abuse of different illicit drugs. METHODS: We studied 3372 male twin pairs from the Vietnam Era Twin Registry. They were interviewed using the Diagnostic Interview Schedule, Version III, Revised to investigate the extent to which the abuse of different categories of drugs occurs together within an individual, as well as the possibility that genetic and environmental factors are responsible for observed co-occurrence. Co-occurrence was quantified using odds ratios and conditional probabilities. Multivariate biometrical modeling analyses were used to assess genetic and environmental influences on co-occurrence. RESULTS: Abusing any category of drug was associated with a marked increase in the probability of abusing every other category of drugs. We found evidence for a shared or common vulnerability factor that underlies the abuse of marijuana, sedatives, stimulants, heroin or opiates, and psychedelics. This shared vulnerability is influenced by genetic, family environmental, and nonfamily environmental factors, but not every drug is influenced to the same extent by the shared vulnerability factor. Marijuana, more than other drugs, was influenced by family environmental factors. Each category of drug, except psychedelics, had genetic influences unique to itself (ie, not shared with other drug categories). Heroin had larger genetic influences unique to itself than did any other drug. CONCLUSION: There are genetically and environmentally determined characteristics that comprise a shared or common vulnerability to abuse a range of illicit drugs.

Adult↗
PubMed1998

A registry-based twin study of depression in men.

BACKGROUND: The only large, registry-based twin study of depression using diagnostic criteria assessed by structured interview included only women. We present results from a comparable study of men. METHODS: Data were collected using a standardized telephone interview of men from the Vietnam Era Twin Registry. Both twins from 3372 pairs participated. Proband-wise concordance rates and biometric modeling were used to analyze the data. RESULTS: The diagnosis of major depression (MD), as defined by DSM-III-R, and the subtype of severe/psychotic MD were significantly affected by genetic (h2=0.36 and 0.39, respectively) and nonshared environmental (e2=0.64 and 0.61, respectively) factors but not by family environmental factors. Dysthymia and mild and moderate MD were affected by family environmental (c2=0.27, 0.08, and 0.14, respectively) and nonshared environmental (e2=0.73, 0.92, and 0.86, respectively) factors but not by genetic factors. Early-onset (before age 30 years) and late-onset (after age 30 years) MD were significantly affected by genetic (h2=0.47 and 0.10, respectively) and nonshared environmental (e2=0.53 and 0.90, respectively) factors. Early-onset MD was significantly more heritable than late-onset MD. CONCLUSIONS: The magnitude of genetic and environmental effects on depression in men is similar to that previously reported in women. Also similar to previous findings, more severe and earlier-onset depression may be more strongly affected by genetic factors, but differences in the reliability of reports of depression associated with severity may inflate estimates of the effect of the unique environment and deflate heritability estimates for less severe depression.

Adult↗
PubMed1998

Beta-human chorionic gonadotropin in cervicovaginal secretions as a predictor of preterm delivery.

OBJECTIVE: This study's objective was to determine whether the concentrations of beta-human chorionic gonadotropin in the secretions of the cervix and vagina could be used to predict preterm delivery in a group of women at high risk for this complication. STUDY DESIGN: Women attending a prematurity prevention clinic at an inner-city hospital July 1, 1996-October 1, 1997, were invited to participate. From those who consented, secretions from the cervix and posterior vaginal fornix were sampled every 2 weeks until delivery, beginning at 24 weeks' gestation. Concentrations of beta-human chorionic gonadotropin were measured with a commercially available enzyme-linked immunosorbent assay. Providers of obstetric care were blinded to the results. Levels of beta-human chorionic gonadotropin in those who were delivered before 34 weeks' gestation and those who were delivered at term were compared. A value >50 mIU/mL was considered elevated. This cutoff value was determined according to beta-human chorionic gonadotropin values obtained during pregnancies that were delivered at term. RESULTS: Of the 146 women asked to participate, 77 consented. There was no difference between participants and nonparticipants with respect to age, race, indication for enrollment in the clinic, gestational age at delivery, or parity. Of the 77 participants, 24 (31%) were delivered before 37 weeks' gestation and 12 (16%) were delivered before 34 weeks' gestation. A single beta-human chorionic gonadotropin value >50 mIU/mL obtained between 24 and 28 weeks' gestation was associated with a significant increase in the incidence of delivery before 34 weeks' gestation (P = .03). This cutoff value had sensitivity, specificity, and positive and negative predictive values for predicting delivery before 34 weeks' gestation of 50%, 87%, 33%, and 93%, respectively. CONCLUSION: These data suggest that the concentration of beta-human chorionic gonadotropin in cervicovaginal secretions may be a useful predictor of preterm delivery.

Adult↗
PubMed1998

Familial influences on gambling behavior: an analysis of 3359 twin pairs.

BACKGROUND: Pathological gambling is becoming an increasing problem in the United States as the number of legalized gambling establishments grows. To examine vulnerability to pathological gambling, we estimated the familial contributions (i.e. inherited factors and/or experiences shared by twin siblings during childhood) to DSM-III-R pathological gambling symptoms and disorder. METHODS: Data were obtained from a telephone interview performed in 1991-92 utilizing the Diagnostic Interview Schedule Version III-Revised. Interviews were administered to 6718 members of the nationally distributed Vietnam Era Twin Registry of male-male monozygotic and dizygotic twin pairs who served in the military during the Vietnam era. RESULTS: Inherited factors explain between 35% (95% CI: 28%, 42%) and 54% (95% CI: 39%, 67%) of the liability for the five individual symptoms of pathological gambling behavior that could be estimated statistically. In addition, familial factors explain 56% (95% CI: 36%, 71%) of the report of three or more symptoms of pathological gambling and 62% (95% CI: 40%, 79%) of the diagnosis of pathological gambling disorder (four or more symptoms). CONCLUSIONS: Familial factors have an important influence on risk for pathological gambling behavior. The increasing access to legalized gambling is likely to result in a higher prevalence of pathological gambling behavior among individuals who are more vulnerable because of familial factors.

Adult↗
PubMed1998

[Influence of huanglian used in combination with huangqin and gancao on the erythrocytic osmotic fragilitas of experimental glucose-6-phosphate dehydrogenase deficiency in rats].

OBJECTIVE: To study the influence of common combination of Huanglian(Coptis chinensis) on the erythrocytic osmotic fragilitas of glucose-6-phosphate dehydrogenase(G6PD) deficiency in rats. METHOD: Various decoctions with Huanglian mixed with Huangqin (Scutellaria baicalensis) and Gancao(Glycyrrhiza uralensis) were orally administered to the G6PD deficiency rat model, and the erythrocytic osmotic fragilitas was measured. RESULT: The erythrocytic osmotic fragilitas after the combined use of Huanglian appears lower than (or equal to) that of Huanglian used alone(or even not used). The fragilitas lowers depending largely on the medicine in combination, dosage and proportion. CONCLUSION: Proper use of Huanglian in combination with Huangqin and Gancao is of some significance in lowering the erythrocytic osmotic fragilitas of G6PD deficiency in rats.

Animals↗
PubMed1998

[Influence of huanglian and berberine on the erythrocytic osmotic fragilitas of experimental glucose-6-phosphate dehydrogenase deficiency in rats].

OBJECTIVE: To make clear the influence of Huanglian (Coptis chinensis) and berberine on the erythrocytic osmotic fragilitas of glucose-6-phosphate dehydrogenase(G6PD) deficiency in rats, so as to infer whether Huanglian and berberine have medicamentosus hemolysis effects. METHOD: Huanglian decoction and berberine solution are applied to the erythrocytes of G6PD deficiency in rats through external and oral administration and the erythrocytic osmotic fragilitas is measured. RESULT: Only at an excessively high dose can the medicines raise the erythrocytic osmotic fragilitas of G6PD deficiency in rats. Berberine and Huanglian have similar effects, but berberine is slightly weaker. CONCLUSION: Focus on the erythrocytic osmotic fragilitas, at a general dose, Huanglian can not cause hemolysis. Huanglian and berberine are of more safety to normal erythrocytes.

Animals↗
PubMed1998

[Studies on the antifertility effect of bis-trichloromethyl sulfone and its reversibility in male rats].

Bis-trichloromethyl sulfone(BTS) given p.o. to male Sprague-Dawley rats at a dose of 10 mg.kg-1.d-1, 6 days a week for 8 weeks(or 30 mg.kg-1.d-1 for 4 weeks), was found to lead to infertility. The density and, in particular, the motility of the spermatozoa in the cauda epididymidis were significantly lower than those of the controls (P < 0.001). The body weight, the sex behavior, the blood testosterone level and the histology of important organs were not significantly different from those of the control rats. Fertility started to recover 4 weeks after cessation of medication and was entirely recovered 2 more weeks later in rats having received BTS for 8 weeks at the dose of 30 mg.kg-1.d-1. In vitro study showed that BTS at a concentration of 0.31 mg.ml-1 would make rat spermatozoa immobile within 20 seconds. These results indicate that BTS has both antifertility effect in male rats and direct inhibitory effect on rat spermatozoa. We conclude that nontoxic doses of BTS can induce reversible infertility in male rats.

Animals↗
PubMed1997

Repair effect of phenylpropanoid glycosides on thymine radical anion induced by pulse radiolysis.

Repair effects on thymine radical anion by six phenylpropanoid glycosides (PPGs), isolated from Pedicularis species, were studied using pulse radiolysis method. The thymine radical anion was produced by the reaction of hydrated electron with thymine. PPGs were added into the thymine solution saturated with N(2). Kinetic analysis showed that transient absorption spectrum of thymine radical anion formed at first, and then after several microseconds of pulse radiolysis changed to that of PPG radical anion. The evidence indicated that thymine radical anion was repaired through one-electron transfer between the radical anion and PPG. Electrophilic phenyl-substituted unsaturated carboxylic group containing in PPGs' structure was able to capture electron from thymine radical anion before it undergo reversible protonation. The reaction rate constants of electron transfer from thymine radical anion to PPGs were within 1.16-2.29 x 10(9) dm(3) mol(-1) s(-1).

Journal Article↗
PubMed1997

Basic fibroblast growth factor treatment delays age-related photoreceptor degeneration in Fischer 344 rats.

This study was undertaken to investigate the potential of basic fibroblast growth factor (bFGF) to delay photoreceptor cell loss in retinas of Fischer 344 rats which exhibit an age-related peripheral retinopathy. Eight male 16-month-old Fischer 344 rats were injected intravitreally with 2.0 micrograms bFGF in the right eye, while the vehicle was injected into the left eye and all rats were killed at two months post-injection. Eight other Fischer rats were injected with either bFGF or vehicle at 16 and again at 18 months, then killed two months later. After enucleation, eyes were processed for light and electron microscopic and morphometric analyses. The distance from the ora serrata to the point where the outer nuclear layer (ONL) in the superior retina was two cells in thickness, called the die-back zone, that represents the extent of the peripheral retinopathy, was compared in bFGF- and vehicle-injected Fischer rats. These measurements revealed that the die-back zone in retinas of eyes injected twice with bFGF was significantly reduced (P < 0.01) when compared to this zone in retinas of age-matched rats that received vehicle injections. However, there was no significant difference (P > 0.05) in this degeneration zone in retinas of 18-month-old rats that received a single-bFGF injection when compared to retinas of respective vehicle-injected rats. In addition, the ONL at 2 and 3 mm from the ora serrata in the superior retina of bFGF-injected 20-month-old Fischer rats was significantly thicker than corresponding regions in retinas of vehicle-control rats. Furthermore, the photoreceptor cells in the superior retina of 20-month-old rats which received two injections of bFGF had normal-appearing inner and outer segments, while the few photoreceptors had short inner and outer segments in vehicle-injected retinas of Fisher rats. These findings reveal that injections of bFGF into eyes of Fischer 344 rats significantly delays the progress of photoreceptor cell degeneration suggesting that exogenous bFGF may act as a survival-promoting factor in these aged retinas.

Aging↗