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PubMedDate not supplied

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls.

BACKGROUND: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. AIM: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). SUBJECTS AND METHODS: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. RESULTS: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). CONCLUSION: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference.

Absorptiometry, Photon↗
PubMed2001

Life events and alcohol consumption among mature adults: a longitudinal analysis.

OBJECTIVE: Four waves of the Health and Retirement Study were used to examine changes in alcohol consumption co-occurring and following stress associated with major health, family and employment events. METHOD: The final sample consisted of 7,731 (3,907 male) individuals between the ages of 51 and 61 at baseline. We used multinomial logit analysis to study associations between important life events and changes in alcohol consumption over a 6-year study period. Interactions between stressful life events, gender and problem drinking were also evaluated. RESULTS: Most persons (68%) did not change their use of alcohol over the entire 6 years. Hospitalization and onset of a chronic condition were associated with decreased drinking levels. Retirement was associated with increased drinking. Widowhood was associated with increased drinking but only for a short time. Getting married or divorced was associated with both increases and decreases in drinking, with a complex lag structure. A history of problem drinking influenced the association between certain life events (e.g., divorce and retirement) and changes in drinking. Gender modified the association between losing a spouse and changes in drinking. CONCLUSIONS: Even after controlling for problem drinking history, social support and coping skills, changes in drinking behavior were related to several life events occurring over a 6-year period for a national cohort of individuals in late middle-age. The magnitude of these relationships, however, varied by gender and problem drinking history.

Adaptation, Psychological↗
PubMed1996

A longitudinal analysis of hepatitis C virus replication following liver transplantation.

BACKGROUND & AIMS: The pathogenesis of graft injury in liver transplant recipients with recurrent hepatitis C virus (HCV) infection remains poorly understood. In this study, the relationship between HCV replication, genotype, and the evolution of graft damage was investigated. METHODS: HCV RNA was quantified in 184 protocol sera from 25 patients transplanted for HCV cirrhosis. HCV isolates were genotyped, and hepatic expression of core and NS4 antigens was sought in protocol allograft biopsy specimens. RESULTS: Acute lobular hepatitis was accompanied by a steep increase in HCV RNA levels and the appearance of core and NS4 antigens in the graft. Methylprednisolone treatment for acute rejection led to a 4-100-fold increase in serum HCV RNA. At the end of follow-up, HCV RNA levels were 3-112 times pretransplant levels and were higher in patients with more severe hepatitis. Progressive liver damage developed in 7 of 14 patients with HCV genotype 1b and in 1 of 11 patients infected with other genotypes (P = 0.03). CONCLUSIONS: Peak viremia levels and the initial detection of HCV antigens in hepatocytes suggests increased viral replication at the time of acute HCV hepatitis in the graft. Genotype 1b and higher viremia levels were associated with more severe chronic graft damage.

Adult↗
PubMed1997

Longitudinal analysis of quantitative virologic measures in human immunodeficiency virus-infected subjects with > or = 400 CD4 lymphocytes: implications for applying measurements to individual patients. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group.

The natural variability of quantitative virologic measures among human immunodeficiency virus (HIV) type 1-infected persons was prospectively studied in 29 untreated persons with >600 CD4 cells/microL and in 15 persons receiving zidovudine monotherapy who had 400-550 CD4 cells/microL at study entry. Cell- and plasma-associated infectious HIV-1, provirus, and virion RNA were determined monthly as were numbers of CD4 and CD8 cells. HIV-1 replication varied widely among subjects with similar CD4 cell counts. The within-individual variability was significantly less than the variability between subjects for all virologic measures. Plasma virion HIV-1 RNA levels had the least variability. A mathematical model was devised to assess whether a potential therapeutic intervention significantly alters peripheral HIV-1 load. The model indicated that three measurements of plasma RNA would be outside the 95th percentile for the expected change in an individual due to natural variability. This approach can be used to accurately assess a therapeutic intervention among persons with low plasma HIV-1 titers.

Adult↗
PubMed1996

Predictors of Chlamydia trachomatis infection among female adolescents: a longitudinal analysis.

Screening guidelines recommend testing all sexually active female adolescents for Chlamydia trachomatis during a pelvic examination at each clinic visit. Such criteria have been based on cross-sectional studies; new evaluations should take into account multiple clinic visits and assess whether criteria are appropriate when a prior test is negative and risk factors are absent. Because repeated observations on an individual may be correlated, the authors used the generalized estimating equation method. Little information exists on subsequent risk of infection; as control programs develop, approaches targeting high-risk populations for recurrent infections are needed. Using data on females aged 15-19 years who visited family planning clinics more than once from 1988 to 1992 (n = 26,921) in Region X (Alaska, Idaho, Oregon, and Washington), the authors constructed a retrospective cohort. Teens with chlamydia at their first visit were at high risk for subsequent infection (odds ratio = 1.6, 95% confidence interval 1.4-1.7). Among teens uninfected at the first visit and without risk factors at the second, prevalence at the second visit was 6%. When intervisit correlations using the generalized estimating equation method were taken into account, predictors of chlamydial infection were consistent with those in previous cross sectional studies cervicitis, friable cervix, and multiple, new, or symptomatic sex partner(s). These findings support screening sexually active female adolescents at each visit, even if prior tests results are available.

Adolescent↗
PubMed1992

A longitudinal analysis of the relationship between in-hospital mortality in New York State and the volume of abdominal aortic aneurysm surgeries performed.

This study uses New York State hospital discharge data to examine the relationship between in-hospital mortality for a patient receiving an abdominal aortic aneurysm resection and the volume of aneurysm operations performed in the previous year at the hospital where the operation took place and by the surgeon performing the operation. Previous research on this topic is extended in several respects: (1) A three-year data base is used to examine the manner in which hospital and surgeon volume jointly affect mortality rate and to examine ruptured and unruptured aneurysms separately; (2) a six-year data base is used to study the "practice makes perfect" hypothesis and the "selective referral" hypothesis; and (3) the degree of specialization of high-volume surgeons is contrasted with that of other surgeons. The results demonstrate a significant inverse relationship between hospital volume and mortality rate for unruptured aneurysms. Further, very few surgeons substantially increased their aneurysm surgery volumes in the six-year study period. Weak selective referral effects were found for both surgeons and hospitals, and higher-volume aneurysm surgeons tended to have much higher specialization rates.

Aged↗
PubMed2006

Alcohol outlets, gonorrhea, and the Los Angeles civil unrest: a longitudinal analysis.

This study tests the effect of neighborhood changes on gonorrhea rates. Prior studies that indicate gonorrhea rates are associated with alcohol outlet density and neighborhood deterioration have been cross-sectional and cannot establish causality. After the 1992 Civil Unrest in Los Angeles, 270 alcohol outlets surrendered their licenses due to arson and vandalism thus providing a natural experiment. We geocoded all reported gonorrhea cases from 1988 to 1996 in LA County, all annually licensed alcohol outlets, and all properties damaged as a result of the civil unrest. We ran individual growth models to examine the independent effects of changes in alcohol outlets and damaged buildings on gonorrhea. The individual growth model explained over 90% of the residual variance in census tract gonorrhea rates. After the civil unrest, a unit decrease in the number of alcohol outlets per mile of roadway was associated with 21 fewer gonorrhea cases per 100,000 (p<.01) in tracts affected by the Unrest compared to those not affected. Neighborhood alcohol outlets appear to be significantly associated with changes in gonorrhea rates. The findings suggest that efforts to control sexually transmitted diseases, including gonorrhea and HIV, should address contextual factors that facilitate high-risk behaviors and disease transmission.

Adolescent↗
PubMed1998

Longitudinal analysis of scaling VO2 for differences in body size during puberty: the Muscatine Study.

PURPOSE: The purpose of this study was to determine an appropriate method to "normalize" oxygen uptake (VO2) for body size in children and adolescents. METHODS: We examined allometric scaling factors for a cohort of 126 children (mean age at baseline = 10.3 yr) participating in a 5-yr follow-up study. Each year for 5 yr we measured peak VO2, submaximal VO2, body mass, height, body composition, and sexual maturation. We sorted the 5-yr data set by sexual maturation and gender and then used the generalized estimating equation method to estimate regression parameters that described the influence of log transformed body mass on log transformed VO2. All analyses were repeated using log transformed fat-free body mass (FFM) in lieu of log transformed body mass. RESULTS: Models using FFM appeared better at eliminating the effect of body size on VO2. In boys a univariate model with a FFM exponent of 0.91 and in girls a univariate model with a FFM exponent of 0.87 satisfactorily normalized peak VO2. However, we could not identify a common body size exponent for both boys and girls. CONCLUSIONS: Results support the use of allometric scaling of VO2 as a function of FFM for maturing boys and girls but indicate that the effects of maturation on the relationship between VO2 and body size differ between boys and girls.

Adolescent↗
PubMed2002

A longitudinal analysis of T-cell epitope-coding regions of hepatitis C virus after liver transplantation.

BACKGROUND: Hepatitis C virus (HCV)-related liver failure is the single leading indication for orthotopic liver transplantation (OLT) worldwide. The mechanisms that underlie the observed differences in natural history of HCV recurrence remain poorly understood. We have previously demonstrated that differential T-cell responses correlate with histologic severity after OLT. We hypothesized that amino acid substitutions within critical T-cell epitopes could lead to increased severity of HCV disease. METHODS: We determined the peptide sequences from sequential serum-derived viral RNA by reverse transcription and direct polymerase chain reaction sequence analysis from 32 HCV genotype 1-infected patients with well-characterized outcomes after liver transplantation. Serum samples were analyzed for HCV sequence the day of OLT and at least one time point post-OLT. To construct evolutionary relationships among the different patient samples, phylogenetic analyses of core and NS3 sequences were performed using a matrix fed into a neighbor-joining tree algorithm. RESULTS: The phylogenetic analyses revealed remarkable conservation within a given individual and no significant differences when comparing patients with severe versus mild recurrence. Accordingly, the synonymous mutation rate was consistently greater than the nonsynonymous substitution rate. The nine epitopic regions analyzed were also preserved so that, with the exception of one patient with mild recurrence, none of the patients demonstrated a shift in viral peptide sequence. CONCLUSIONS: HCV core and NS3 viral peptide sequences are identical before and after OLT in most patients, suggesting that the prevalent sequence is preserved in most cases, and viral variants are competent to establish infection after OLT. Although these results do not support viral mutation as a dominant pathogenic mechanism after OLT, other viral regions need to be analyzed.

Adult↗
PubMed1995

Kinetics of Gag-specific cytotoxic T lymphocyte responses during the clinical course of HIV-1 infection: a longitudinal analysis of rapid progressors and long-term asymptomatics.

To gain more insight into the role of HIV-1-specific cytotoxic T lymphocytes (CTL) in the pathogenesis of AIDS, we investigated temporal relations between HIV-1 Gag-specific precursor CTL (CTLp), HIV-1 viral load, CD4+ T cell counts, and T cell function. Six HIV-1-infected subjects, who were asymptomatic for more than 8 yr with CD4+ counts > 500 cells/mm3, were compared with six subjects who progressed to AIDS within 5 yr after HIV-1 seroconversion. In the long-term asymptomatics, persistent HIV-1 Gag-specific CTL responses and very low numbers of HIV-1-infected CD4+ T cells coincided with normal and stable CD4+ counts and preserved CD3 mAb-induced T cell reactivity for more than 8 yr. In five out of six rapid progressors Gag-specific CTLp were also detected. However, early in infection the number of circulating HIV-1-infected CD4+ T cells increased despite strong and mounting Gag-specific CTL responses. During subsequent clinical progression to AIDS, loss of Gag-specific CTLp coincided with precipitating CD4+ counts and severe deterioration of T cell function. The possible relationships of HIV-1 Gag-specific CTLp to disease progression are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The first 900: a nine-year longitudinal analysis of consecutive adolescent inpatients.

Data for the presenting complaints, average age and sex distribution, average length of stay and the discharge diagnosis for 900 consecutive adolescents treated at the Adolescent Center of Houston International Hospital between 1974 and 1982 were reviewed. The number of cases remained fairly constant over the 9 years. As the males and females showed an increase in age, the increase in age for males (13.4 years to 15.2 years) was greater than that for females (14.4 years to 15.0 years). The average age for male admissions during 1974-1976 was significantly lower than 1980-1982 (p less than 0.03). The average length of stay for males during 1980-1982 was significantly greater than 1974-1976 (p less than 0.05). The most frequent presenting symptoms in decreasing order for 1974-1982 were depression, school problems, family problems, threatening behavior, runaway behavior, and suicidal ideation. Depression increased from 15.6% in 1974-1976 to 29.6% of presenting symptoms. Substance abuse increased from 4% (1974-1976) to 8.8% (1980-1982). Suicidal ideation increased three-fold over the same period (3.3% to 10.6%). A significantly greater number of males presented with 1) impulsivity, 2) aggressiveness, 3) withdrawal behavior, 4) stealing, and 5) disruptive behavior. A significantly greater number of females presented with 1) runaway behavior, and 2) suicidal ideation. The 10 most frequent discharge diagnoses are listed. Depression as a diagnosis increased almost four-fold between 1977-1979 and 1980-1982 (7.6% versus 27.5%).

Adjustment Disorders↗
PubMed1999

Bacterial colonisation during GTR treatment. A longitudinal analysis.

UNLABELLED: The purpose of the present study was to evaluate the long-term biological and clinical effects of a controlled delivery system releasing tetracyclines during the healing of interproximal periodontal defects treated by the technique of guided tissue regeneration (GTR) using e-PTFE membranes. METHODS: Fifteen patients, each with two comparable interproximal periodontal defects, underwent surgical treatment with e-PTFE membranes in conjunction with tetracycline fibres at the test site and e-PTFE membranes alone at the control site. Microbiological specimens were taken from each site treated at baseline (T0) and one year after surgery (T4). Plaque index (PI), gingival index (GI), pocket depth at probing (PD) and attachment level at probing (PAL) were recorded at baseline (T0) and one year after surgery (T4). The presence of selected pathogenic microbial species, Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium Nucleatum (Fn) and Actinobaccillus Actinomicetemcomitans (Aa), was investigated and these species were identified by cultural methods. RESULTS: No statistically significant difference in the level of periodontal pathogens was detected between the test and control sites at time T4. Likewise, no significant clinical difference between the test site and the control site was detected at time T4. CONCLUSIONS: The results suggest that tetracycline fibres used in conjunction with e-PTFE membranes do not provide and further clinical and microbiological improvement or effect the healing of periodontal defects one year after GTR treatment.

Anti-Bacterial Agents↗
PubMed1996

Experimental human Plasmodium falciparum infections: longitudinal analysis of lymphocyte responses with particular reference to gamma delta T cells.

The kinetics of the gamma delta T-cell response was analysed in the context of the overall haematological response in subjects experimentally infected with sporozoites of Plasmodium falciparum. Numbers of gamma delta and alpha beta T cells and NK cells declined markedly during infection to reach minimum values 12-13 days post-infection when the patients were ill. This decline commenced from the beginning of the erythrocytic cycle and well before parasites could be detected microscopically and clinical symptoms developed. Platelet numbers also declined. In vivo activation of gamma delta T cells was evident with sequential up-regulation of the activation markers CD69 and HLA-DR. gamma delta T cell numbers were highest after treatment with the majority being CD4-CD8-, HLA-DR+ and showing reduced CD45RA expression. Contrary to some published observations gamma delta T-cell percentages remained within the normal range. Little evidence of upregulation of activation or memory markers was observed in the alpha beta T-cell population. In vitro proliferative responses to malaria antigen which involve gamma delta T cells were lost as the infection progressed and the lymphocyte count declined but these could be restored with the addition of exogenous IL-2 to cultures. The authors findings are consistent with a protective and/or immunomodulatory role for gamma delta T cells in malaria.

Adult↗
PubMed1999

Relapsing-remitting multiple sclerosis: longitudinal analysis of MR images--lack of correlation between changes in T2 lesion volume and clinical findings.

PURPOSE: To determine the relationship between T2 lesion volume and either disability measurements or change in T2 lesion volume over time in multiple sclerosis (MS). MATERIALS AND METHODS: Eighteen patients (age range, 26-53 years) with clinically proved relapsing-remitting MS were examined every 6 months for over 2 years. Three-millimeter-thick contiguous images of the whole brain were obtained. T2 lesion volume was calculated with a highly reproducible volumetric computer method. RESULTS: A substantial annual increase in T2 lesion volume, with a median annual increase of approximately 8%, was demonstrated. However, there was no significant correlation between absolute T2 lesion volume and either the absolute expanded disability status scale (EDSS) grade (P = .32) or the absolute ambulation index (AI) (P = .20). In addition, no significant correlation between change in T2 lesion volume and change in EDSS grade (P = .42) or AI (P = .37) was found. There was no significant correlation between T2 lesion volume and duration of disease (P = .08). CONCLUSION: There is no significant correlation between T2 lesion volume and standardized disability measurements despite a substantial increase in T2 lesion volume over time. Patients have an increase in total T2 lesion volume in the brain regardless of their clinical status or disability measurements. T2 lesion volumes as outcomes in therapeutic clinical trials on MS should be viewed as secondary outcomes rather than as surrogate markers of clinical responses.

Adult↗
PubMed2006

Dyslipidemia among perinatally HIV-infected children enrolled in the PACTS-HOPE cohort, 1999-2004: a longitudinal analysis.

BACKGROUND: Protease inhibitor (PI)-containing regimens have led to improved survival among HIV-infected children. However, adverse effects, including dyslipidemia, may put children at risk for cardiovascular disease. METHODS: Serum cholesterol and triglyceride levels were recorded on perinatally HIV-infected children participating in the PACTS-HOPE cohort (1999-2004). Hypercholesterolemia (HC) was defined as cholesterol > or =200 mg/dL and hypertriglyceridemia (HT) as triglycerides >or =150 mg/dL. HC and HT were modeled over time using generalized estimating equations. RESULTS: For 178 children, 47% met criteria for HC and 67% for HT at least once during the study period. In generalized estimating equation models, PI use, undetectable viral load, and immunologic category 3 were independent predictors of HC. HT was significantly associated with PI use and body mass index (BMI) > or =90th percentile for age and gender. Among children on PI-containing regimens, HC was significantly associated with multiple PIs and undetectable viral load; HT was predicted by body mass index > or =90th percentile and ritonavir use. The prevalence of clinical lipodystrophy was 5.6% (10/178). CONCLUSIONS: Children on PI-containing regimens have a higher risk of both HC and HT. Lipid levels should be measured regularly in children on antiretroviral treatment. Interventions such as diet, exercise, or lipid-lowering drug therapy may benefit some children.

Adolescent↗
PubMed2001

Longitudinal analysis of CD8(+) T-cell phenotype and IL-7, IL-15 and IL-16 mRNA expression in different tissues during primary simian immunodeficiency virus infection.

Infection of macaques with pathogenic isolates of simian immunodeficiency virus (SIV) represents a useful model of HIV infection that offers the unique opportunity to investigate the very early modifications that affect CD8(+) T-lymphocyte subsets and related cytokines during lentiviral infection. Herein, three cynomolgus macaques were inoculated intravenously with a pathogenic isolate of SIVmac 251. In fresh isolated mononuclear cells from blood, lymph node and bronchoalveolar lavage, we analyzed changes in the phenotype of CD8(+) T cells and we used reverse transcription-PCR to monitor the expression of IL-7, IL-15 and IL-16 mRNA. We demonstrated that an expansion of CD8(+)CD28(-) T cells occurs from the third week of infection on in the peripheral blood and in the lung, whereas CD8(+)CD28(+) T cells expand in the lymph nodes. Concomitantly, we evidenced mRNA modulations in IL-16, IL-15 and IL-7 expression in the three compartments studied. The containment of systemic viral replication was associated with an overexpression of IL-16 mRNA in the lung and in the peripheral blood. Given the immunomodulatory properties of IL-15 and IL-7 and the potential antiviral ability of IL-16, these perturbations could have important implications in early viral dissemination and HIV immunopathogenesis.

Animals↗
PubMed2006

Socioeconomic inequalities in health: a comparative longitudinal analysis using the European Community Household Panel.

This study measures socioeconomic inequalities in health across European Union Member States between 1994 and 2001. The analysis is based on the European Community Household Panel Users' Database (ECHP-UDB) and uses two binary indicators of health limitations for the full 8 waves of available data. Short- and long-run concentration indices together with mobility and health achievement indices are derived for indicators of severe health limitation and any health limitation. Results demonstrate the existence of socioeconomic inequality in health across Member States in both the short-term (1 year) and the long-term (up to 8 years), with health limitations concentrated among those with lower incomes. For all countries, the long-run indices show that income-related inequalities in health widen over time, in the sense that the longer the period over which an individual's health and income are measured the greater the measure of income-related health inequality. The ranking of countries according to their prevalence of illness differs from ranking by overall health achievement, which takes account of inequalities. This means that an equity-efficiency trade-off has to be faced in evaluating the performance of different countries and in comparing countries with diverse health and social welfare systems.

Cross-Sectional Studies↗
PubMed1987

Violence in Playboy magazine: a longitudinal analysis.

This paper analyzes the amount of violence in cartoons and pictorials from January 1954, through December 1983 in Playboy magazine. Inasmuch as the Attorney General's Commission on Pornography and Obscenity has focused upon magazines such as Playboy as potentially harmful to society because of the violence merged with sex, such an analysis is appropriate at this time. Each cartoon and pictorial for each issue of Playboy for the 30-year-period was examined for violent depictions. The average number of violent cartoons for the 30-year-period was 6.92/year or 0.58/issue. The average number of violent pictorials was less with an average of 1.89/year or 0.16/issue. The ratio of violent cartoons or pictorials to the total number of cartoons or pictorials was small. The ratio of violent cartoons to all cartoons was 25.2/1000 and for violent pictorials to all pictorials it was 8.6/1000. Moreover, the ratio of violent cartoons to total pages was 2.86/1000 and for violent pictorials 0.78/1000 pages. Although the overall number and ratio of violent cartoons and pictorials in Playboy over the 30-year-period examined was rare, a major question addressed was whether the amount of violence was increasing. Rather than a linear relation, a curvilinear relationship was observed with the amount of violence on the decrease in recent years. Although the effects of violence in sexual material is still being debated, those who argue for greater censorship of magazines such as Playboy because of its depictions of violence need a new rationale to justify their position.

Cartoons as Topic↗