Temporal integration differences between crossed and uncrossed stereoscopic mechanisms

In this study, we investigated temporal integration of disparity information for crossed and uncrossed stereopsis. Across three experiments, exposure duration thresholds were measured for stereoscopic stimuli created from dynamic random-dot stereograms. In Experiment 1, an investigation of disparity detection showed that detection thresholds were equal for the crossed and uncrossed directions. In Experiment 2, an examination of duration limits for depth perception showed that critical durations were lower, and depth more veridical, for crossed depth than for uncrossed depth. In Experiment 3, an investigation of depth discrimination revealed that discrimination thresholds were lower for crossed depth than for uncrossed depth. These results suggest that crossed and uncrossed mechanisms differ in terms of their temporal integration properties at processing levels involving the computation and discrimination of depth.

Correlates of hepatitis C virus infections among injection drug users

Injection drug users are at high risk for hepatitis C virus (HCV) infection. In Baltimore, Maryland, the prevalence of anti-HCV is greater among injection drug users who are black, human immunodeficiency virus (HIV) infected, have injected longer, have injected more frequently, and have injected cocaine than among other injection drug users. HCV infection occurs quickly after the initiation of injecting illicit drugs, with 78% of study participants anti-HCV positive after 2 years of injecting. The prevalence of anti-HCV among injection drug users does not appear to be related to socioeconomic factors or sexual practices. Some injection drug users remain free of anti-HCV even after years of injecting and serologic evidence of other bloodborne pathogens. Some of these injection drug users have HCV infection, demonstrated by HCV RNA in their sera. However, the basis for viral persistence in the absence of anti-HCV and for the absence of HCV infection in long-term drug users is not known. Further studies are indicated to determine the mechanism or mechanisms for the absence of anti-HCV in persons exposed to the virus, because the biologic basis for this condition may elucidate the elements missing in the immune response of the majority of HCV-exposed persons who acquire persistent infection. In addition, interventions to prevent HCV infections should be applied in populations at risk for injection drug use early or before drug use begins.

Incidence and risk factors for human T-lymphotropic virus type II seroconversion among injecting drug users in Baltimore, Maryland, U.S.A

To determine the incidence of and risk factors for human T-lymphotropic virus, type II (HTLV-II) seroconversion among injecting drug users (IDUs), specimens from IDUs recruited into the ALIVE Study in 1988/1989 were assayed at baseline for antibody to HTLV with use of enzyme immunoassay and Western blot. Participants were monitored semiannually with venipuncture and interviews. In 1992, the most recent sera of HTLV-negative participants were tested for HTLV with use of enzyme immunoassay and confirmed and typed by Western blot. For positive cases, assays were then performed for all intervening visits to determine the calendar time of seroconversion. Incidence rates were estimated using person-time. Risk factor analysis used a nested case-control design, with up to seven controls per case matched by time of study entry and duration of follow-up. At baseline, 251 HTLV-positive, 22 indeterminate, and 2,574 HTLV-seronegative IDUs were identified. Follow-up of the seronegative IDUs identified 38 seroconverters (all HTLV-II) over 5,813.6 person-years, for a rate of 0.7/100 person-years. Median lag time for seroconversion was 6.8 months. Factors associated with HTLV-II seroconversion included a specific needle-sharing practice called "backloading" within the previous 6 months [odds ratio (OR) = 6.52; 95% confidence interval (CI) = 1.94-21.95] and a baseline history of receiving money for sex (OR = 3.36; 95% CI = 1.32-8.57). Of those with more than one sex partner in the past 6 months, women were more likely than men to seroconvert (OR = 5.77; 95% CI = 1.33-25.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Understanding and helping families with neurodevelopmental and neuropsychiatric special needs

Children with persistent neurodevelopmental and neuropsychiatric problems have extensive treatment, care, and community service needs. The child's disabilities can create new responsibilities, emotions, roles, and goals for the family. This article provides a framework for identifying and categorizing children with special needs. In addition, methods for assessing the family's psychoeducational, social, and emotional concerns are presented.

Extracellular and intracellular acid-base status in the freshwater crayfish, Austropotamobius pallipes between 1 and 12(o)C

Freshwater crayfish, Austropotamobius pallipes, caught in the winter when water temperature was 5 °C, were acclimated in the laboratory to 5 °C for 1 week and to 1 and 12 °C for 1 month before haemolymph and tissue samples were taken for acid­base analysis. In vivo, haemolymph (extracellular) pH increased by 0.14 units between 5 and 1 °C but remained unchanged between 5 and 12 °C, giving an overall deltapHe/deltat value of -0.009 pH units °C-1 and an [H+] value of +3.3 nmol l-1. Haemolymph withdrawn from crayfish acclimated to 1 °C and warmed anaerobically in vitro to 12 °C had a deltapHe/deltat value of -0.010 pH units °C-1. This was depressed compared with the values of -0.015 and -0.016 pH units °C-1 obtained from haemolymph withdrawn from crayfish held at 5 and 12 °C, respectively, but changes in H+ concentration were similar in all three groups. There was little change in intracellular pH with rise in temperature in either claw muscle (deltapHi/deltat=-0.003 pH units °C-1) or hepatopancreas (deltapHi/deltat=-0.006 pH units °C-1). In the heart, deltapHi/deltat paralleled that in the haemolymph (-0.010 pH units °C-1), but the largest change was found in the abdominal muscle (-0.025 pH units °C-1). In all tissues apart from claw muscle, there was a metabolic acidosis, with an increase in metabolic acid load as temperature rose from 1 to 12 °C. The depressed in vivo deltapHe/deltat value and the differences in deltapHi/deltat between the tissues were attributed to active regulation of pHi, possibly to control enzyme function in the intracellular compartments. Tissues that are functionally important in the winter months, such as abdominal muscle, followed alphastat regulation, whereas tissues that are less active in the winter, such as claw muscle and hepatopancreas, maintained pHi irrespective of temperature, resulting in a relatively acidotic pHi, which may serve to depress the activity of metabolic enzymes.

Toward multiculturality. Implications for the pediatrician

Pediatricians must become more aware of America's growing ethnic, racial, and immigrant populations. A pediatrician who is not a member of an ethnic group can certainly become a minority family's doctor. It is the position of this article that the pediatrician must understand the importance of cultural issues and allow the family to become his or her guide. The suggested interview is provided as an outline for readers to both use with immigrants and to discover personal areas of cultural awareness and either knowledge or sensitivity gaps. Some individuals may want to only think about the questions and mentally relate them to certain families. Considering questions of this nature can help each pediatrician to become better spontaneous interviewers and to keep cultural concepts within working memory.

When community resources fail. Assisting the frightened or angry parent

The failure to receive expected community services or specialized in-home medical care can be upsetting for some parents. This article is designed to help pediatricians interpret inappropriate family behaviors and to therapeutically defuse verbal anger, unrealistic expectations, and unfounded fears.

Evidence that the Saethre-Chotzen syndrome locus lies between D7S664 and D7S507, by genetic analysis and detection of a microdeletion in a patient

The locus for Saethre-Chotzen syndrome, a common autosomal dominant disorder of craniosynostosis and digital anomalies, was previously mapped to chromosome 7p between D7S513 and D7S516. We used linkage and haplotype analyses to narrow the disease locus to an 8-cM region between D7S664 and D7S507. The tightest linkage was to locus D7S664 (Z = 7.16, theta = .00). Chromosomes from a Saethre-Chotzen syndrome patient with t(2;7) (p23;p22) were used for in situ hybridization with YAC clones containing D7S664 and D7S507. The D7S664 locus was found to lie distal to the 7p22 breakpoint, and the D7S507 locus was deleted from the translocation chromosomes. These genetic and physical mapping data independently show that the disease locus resides in this interval.

PCR SSCP reveals haplotype related polymorphism of PERB1: a new marker for MHC beta block typing

Many new Major Histocompatibility Complex (MHC) genes have been discovered in the last 5 years. Defining the polymorphism of these new genes may elucidate their function and their relevance to diseases with MHC associations. Polymerase chain reaction and single stranded conformation polymorphism (PCR SSCP) analyses were used to detect sequence polymorphisms of PERB1 demonstrated by comparing the available genomic sequence of four haplotypes. This study showed that PCR SSCP of PERB1 is reproducible. In addition, PERB1 alleles segregate within families together with MHC haplotypes. Typing results from the Forth Asia and Oceania Histocompatibility Workshop (4AOHW) cell panel indicate that the identified polymorphisms of PERB1 are "haplotypic', i.e., unrelated individuals carrying the same MHC ancestral haplotypes carry the same PERB1 SSCP pattern. Interestingly, PERB1 SSCP patterns allow the distinction of ancestral haplotypes which share HLA-B serological specificities, such as HLA-B44 and therefore this analysis can be used to further define MHC haplotypes and thus to improve our understanding of the evolution of this complex.

Comparison of tracheal extubation in patients deeply anesthetized with desflurane or isoflurane

A randomized, single-blind study design was used to compare desflurane with isoflurane in 31 adults undergoing intraocular surgery to determine whether the lower blood:gas partition coefficient of desflurane would result in a more rapid emergence after endotracheal extubation of deeply anesthetized patients. A standardized general anesthetic technique was used, consisting of sufentanil, 0.25 microgram/kg, and propofol, 1.5 mg/kg, followed by either isoflurane (n = 15) or desflurane (n = 16) in an air/oxygen mixture. After the operation and reversal of residual neuromuscular block, spontaneous ventilation was reestablished and the patients' tracheas were extubated at equianesthetic concentrations of desflurane and isoflurane (i.e., approximately 1.4 times the minimum alveolar anesthetic concentration [MAC]). Spontaneous movements occurred 5.7 (+/- 2.4) and 8.7 min (+/- 3.1; P = 0.005) after extubation in the desflurane and isoflurane groups, respectively. Eye opening and orientation also occurred significantly earlier after desflurane compared to isoflurane. Patients receiving desflurane (versus isoflurane) were also able to be transferred from the operating room significantly earlier (10.4 +/- 3.7 vs 14.5 +/- 4.3 min, P = 0.01). Use of desflurane (versus isoflurane) was not associated with an increased incidence of coughing or airway irritation during the emergence period. However, use of desflurane did not significantly reduce the duration of the postanesthesia care unit (PACU) stay or alter later recovery events compared to isoflurane. In conclusion, the more rapid emergence would favor the use of desflurane when tracheal extubation during deep anesthesia is required.

Inhibitory effect of milk fat on milk secretion in the mouse: a re-examination

Lactating mice were treated I.P. with cow milk, skim milk, milk lipid extract, preparations of milk fat globule membranes and fat globule-enriched milk (cream). Milk, but not skim milk, inhibited litter growth significantly. None of the fractions of milk fat globules had any apparent effect on litter growth. Litter growth was reduced markedly and maternal health adversely affected by cream. It is concluded that previous studies in which milk was injected I.P. cannot be taken to indicate that milk contains a lipid or lipid-soluble inhibitor of milk secretion in addition to the protein inhibitor discovered in milk more recently.

The incidence of HIV-1 infections in village populations of northern Thailand

OBJECTIVES

To determine the age- and sex-specific prevalence of HIV-1 infection in a general ambulatory population in northern Thailand in 1990 and 1992, and the incidence of HIV-1 infections between 1990 and 1992.

DESIGN

Health fairs were held in five villages in Chiang Mai province in northern Thailand between December 1989 and January 1990 and again in January 1992. Participation of all village residents was encouraged. Villagers were offered testing for serological markers of hepatitis B virus (HBV) infection and free HBV vaccine was made available to susceptible individuals.

METHODS

Sera from the two surveys were linked and coded by demographic characteristics (age group and sex). Individual identifiers were removed and the sera tested for HIV-1 antibodies by enzyme-linked immunosorbent assay with Western blot confirmation.

RESULTS

In 1990, 21 out of 1161 (1.8%) individuals were HIV-1-seropositive; the infection rates were 3.3% in men and 0.5% in women. In 1992, 44 out of 956 (4.6%) individuals were HIV-1-seropositive. Among people included in both surveys the 2-year incidence was 2.0% in women and 4.1% in men (annual incidence, 1.0 and 2.05%, respectively); however, among men over the age of 14 years the 2-year incidence was 6.3%, whereas among women of this age the 2-year incidence was 1.8% (annual incidence, 3.15 and 0.9%, respectively). Among men, incident HIV-1 infections were common, even among those aged 50 years or more.

CONCLUSIONS

Infections with HIV-1 are disturbingly frequent and increasing among adult populations in semi-rural areas of northern Thailand. In order to contain further spread of the epidemic public-health strategies targeted to the general public, including those in rural areas, will be needed.

Localization of the achondroplasia gene to the distal 2.5 Mb of human chromosome 4p

Achondroplasia has been mapped to 4p16.3 using 18 multigenerational families with achondroplasia and 10 short tandem repeat polymorphic markers from this region. No evidence of genetic heterogeneity was found. Analysis of a recombinant family localizes the achondroplasia locus to the 2.5 Mb region between D4S43 and the telomere. Multipoint linkage analysis favors placement telomeric of D4S412. The establishment of closely linked markers will facilitate positional cloning of the achondroplasia gene and permit prenatal diagnosis of homozygous achondroplasia for at risk couples.

Risk factors associated with prevalent HIV-1 infection among pregnant women in Rwanda. National University of Rwanda-Johns Hopkins University AIDS Research Team

This study evaluated risk factors associated with prevalent HIV-1 infection among pregnant women in a semi-rural but densely populated area surrounding the town of Butare in Rwanda. Overall seroprevalence was 9.3% in 5690 pregnant women who sought antenatal care at one of five health centres. Factors associated with higher seroprevalence of HIV-1 included history of multiple sexual partners, history of at least one sexually transmitted disease (STD), relatively high socioeconomic status (SES), being unmarried, young age at first pregnancy, and low gravidity. Women who had used oral contraceptives, smoked more than one cigarette per day, whose partners were circumcised, and had had sex to support themselves were also at higher risk of being infected. A history of blood transfusion in the past 5 years was not associated with HIV-1 infection. History of multiple sexual partners, history of STD, high household income, partner circumcision, and past oral contraceptive use remained strongly associated with HIV-1 infection even when simultaneously controlling for other covariates. Among legally married women who lacked sexual behaviour risk factors, history of STD, high SES, young age at first pregnancy, and low gravidity were significantly associated with HIV-1 seroprevalence.