Search PubMed⌕ Search

Biomedical subjects

J Hecht

Publications and source records attributed to J Hecht.

At least 19 recordsLinked to original sources
PubMed2003

A single amphioxus and sea urchin runt-gene suggests that runt-gene duplications occurred in early chordate evolution.

Runt-homologous molecules are characterized by their DNA binding runt-domain which is highly conserved within bilaterians. The three mammalian runt-genes are master regulators in cartilage/bone formation and hematopoiesis. Historically these features evolved in Craniota and might have been promoted by runt-gene duplication events. The purpose of this study was therefore to investigate how many runt-genes exist in the stem species of chordates, by analyzing the number of runt-genes in what is likely to be the closest living relative of Craniota-amphioxus. To acquire further insight into the possible role of runt-genes in early chordate evolution we have determined the number of runt-genes in sea urchins and have analyzed the runt-expression pattern in this species. Our findings demonstrate the presence of a single runt-gene in amphioxus and sea urchin, which makes it highly likely that the stem species of chordates harbored only a single runt-gene. This suggests that runt-gene duplications occurred later in chordate phylogeny, and are possibly also associated with the evolution of features such as hematopoiesis, cartilage and bone development. In sea urchin embryos runt-expression involves cells of endodermal, mesodermal and ectodermal origin. This complex pattern of expression might reflect the multiple roles played by runt-genes in mammals. A strong runt-signal in the gastrointestinal tract of the sea urchin is in line with runt-expression in the intestine of nematodes and in the murine gastrointestinal tract, and seems to be one of the phylogenetically ancient runt-expression domains.

Amino Acid Sequence↗
PubMed2001

[Superior mesenteric vein syndrome: a case of duodenal stenosis caused by atypical malposition of the superior mesenteric vein].

Cases in which mesenteric vessels lead to stenosis of the duodenum are very rare. Several cases have been reported of patients suffering from stenosis of the last third of the duodenum due to a malpositioning of the superior mesenteric artery or the left renal vein. We report a 78-year-old patient who was suffering from dyspepsia, pain in the upper abdominal region, nausea, and vomiting. The medical history revealed that the patient had undergone a subtotal gastrectomy according to Billroth II at the age of 19 because of similar complaints. In the last 20 years the patient had to be laparotomized several times for ileus of the small intestine. Now the patient presented abdominal complaints with nausea and pressure in the upper abdominal region. Assuming an efferent-loop syndrome and adhesions, the patient was laparotomized. We discovered malpositioning of the superior mesenteric vein, leading to stenosis of the superior part of the duodenum. In fact, 60 years ago surgeons performed a duodenojejunostomy, circumvening the stenosis of the duodenum. With a "delay of 60 years", we then performed a subtotal gastrectomy according to Billroth II. The postoperative course was uneventful; the patient had no complaints and increased in body weight. To our knowledge, this is the first time that a stenosis of the duodenum due to malpositioning of the superior mesenteric vein has been observed.

Aged↗
PubMed2001

Serum-free cultured keratinocytes fail to organize fibronectin matrix and possess different distribution of beta-1 integrins.

The development of serum free medium formulation for culturing keratinocytes was a breakthrough in achieving a high number of epidermal cells for experimental and therapeutic studies, in particular to support the wound healing process. It is not clear, however, if switching the cells to highly proliferative phenotype may reflect change in other cellular functions important for the wound repair as their adhesive interactions with the extracellular matrix components. Remodelling of the extracellular matrix, particularly of fibronectin plays an essential role for guiding the cells during wound healing. The molecular mechanisms for organization of this provisional fibronectin matrix, however, are still not clear. We found that keratinocytes in serum containing medium, although in fewer numbers than fibroblasts, were able to remove adsorbed fluorescent labelled fibronectin from the substratum and reorganize it in a fibrilar pattern along the cell periphery. After 3 days the secreted fibronectin had also been organized as matrix-like fibers and as clusters deposited on the substratum after migrating cells. In contrast, serum free cultured keratinocytes fail to organize pre-adsorbed fluorescent labelled fibronectin, as well as the secreted fibronectin, although they grow very well under these conditions. Switching the cells to serum containing medium initiates the removal of fluorescent labelled fibronectin from the substratum, however without reorganization in fibrillar pattern. Most likely, these keratinocytes remove fluorescent labelled fibronectin by the expression of proteolytic activity, rather than with the mechanical function of beta(1) integrins. The latter were diffusely dispersed in serum containing conditions and tend to organize in focal adhesions in serum free cultured cells. We assumed their transient expression and different affinity state might be important for the keratinocyte migration and matrix assembly mechanism.

Blood Physiological Phenomena↗
PubMed2000

Application of motivational interviewing to prenatal smoking cessation: training and implementation issues.

OBJECTIVE: Three of the Smoke-Free Families projects incorporated motivational interviewing (MI) into prenatal smoking cessation interventions. This paper describes the process involved in training healthcare providers to use MI and the issues encountered in implementing the protocols. DESIGN: Health care providers at all three sites attended local training workshops in which they learned to apply the basics of MI to their study protocol. All sites followed a similar outline and schedule for training and monitoring. SETTINGS: The MI interventions were delivered through home visits in Boston, Massachusetts; phone based counselling calls to patients' homes in Southern California; and in urban and rural prenatal clinics throughout East Texas. PARTICIPANTS: Public health nurse and social work case managers, who were already employed by health care agencies, delivered the MI interventions. MEASURES: Pre- and postintervention assessments and feedback from trainers and investigators at all three sites. RESULTS: Providers were enthusiastic about the training workshops, which they rated as effective in preparing them to deliver the intervention. Barriers to implementation included difficulty in contacting patients and competing demands on providers' time. CONCLUSIONS: Conducting initial training for providers is the first step in developing skills to deliver motivational interventions. Additional time and resources are needed for ongoing skill building and monitoring of intervention delivery.

Education↗
PubMed1999

Expression of the heparan sulfate proteoglycan, perlecan, during mouse embryogenesis and perlecan chondrogenic activity in vitro.

Expression of the basement membrane heparan sulfate proteoglycan (HSPG), perlecan (Pln), mRNA, and protein has been examined during murine development. Both Pln mRNA and protein are highly expressed in cartilaginous regions of developing mouse embryos, but not in areas of membranous bone formation. Initially detected at low levels in precartilaginous areas of d 12.5 embryos, Pln protein accumulates in these regions through d 15.5 at which time high levels are detected in the cartilage primordia. Laminin and collagen type IV, other basal lamina proteins commonly found colocalized with Pln, are absent from the cartilage primordia. Accumulation of Pln mRNA, detected by in situ hybridization, was increased in d 14.5 embryos. Cartilage primordia expression decreased to levels similar to that of the surrounding tissue at d 15.5. Pln accumulation in developing cartilage is preceded by that of collagen type II. To gain insight into Pln function in chondrogenesis, an assay was developed to assess the potential inductive activity of Pln using multipotential 10T1/2 murine embryonic fibroblast cells. Culture on Pln, but not on a variety of other matrices, stimulated extensive formation of dense nodules reminiscent of embryonic cartilaginous condensations. These nodules stained intensely with Alcian blue and collagen type II antibodies. mRNA encoding chondrocyte markers including collagen type II, aggrecan, and Pln was elevated in 10T1/2 cells cultured on Pln. Human chondrocytes that otherwise rapidly dedifferentiate during in vitro culture also formed nodules and expressed high levels of chondrocytic marker proteins when cultured on Pln. Collectively, these studies demonstrate that Pln is not only a marker of chondrogenesis, but also strongly potentiates chondrogenic differentiation in vitro.

Animals↗
PubMed1999

Three oral formulations of methadone. A clinical and pharmacodynamic comparison.

This study was done to determine whether there were any differences in subjective symptoms of opiate withdrawal or methadone pharmacodynamics among patients as they were switched between three different oral formulations of methadone. Patients enrolled in a three-way double-blind crossover trial of three methadone formulations. Subjective symptoms and pharmacodynamic measures were assessed throughout the study period. Eighteen patients were enrolled the study. No statistically significant differences in any of the pharmacodynamic parameters studied were found among the three methadone preparations. There was no significant difference among preparations in the rate and extent of rise and fall in plasma methadone levels during a 24-hour intensive sampling period. Subjective symptoms also did not correlate with methadone formulation. Intolerance to changes in methadone formulation, often observed clinically, do not appear to have a pharmacodynamic basis. Our findings support the notion that such change intolerance reflects factors other than the pharmacologic properties of the different formulations of methadone.

Adult↗
PubMed1999

CBFA1 mutation analysis and functional correlation with phenotypic variability in cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is a dominantly inherited skeletal dysplasia caused by mutations in the osteoblast-specific transcription factor CBFA1. To correlate CBFA1 mutations in different functional domains with the CCD clinical spectrum, we studied 26 independent cases of CCD and a total of 16 new mutations were identified in 17 families. The majority of mutations were de novo missense mutations that affected conserved residues in the runt domain and completely abolished both DNA binding and transactivation of a reporter gene. These, and mutations which result in premature termination in the runt domain, produced a classic CCD phenotype by abolishing transactivation of the mutant protein with consequent haploinsufficiency. We further identified three putative hypomorphic mutations (R391X, T200A and 90insC) which result in a clinical spectrum including classic and mild CCD, as well as an isolated dental phenotype characterized by delayed eruption of permanent teeth. Functional studies show that two of the three mutations were hypomorphic in nature and two were associated with significant intrafamilial variable expressivity, including isolated dental anomalies without the skeletal features of CCD. Together these data show that variable loss of function due to alterations in the runt and PST domains of CBFA1 may give rise to clinical variability, including classic CCD, mild CCD and isolated primary dental anomalies.

Animals↗
PubMed1999

Has asthma medication use in children become more frequent, more appropriate, or both?

OBJECTIVE: Despite national initiatives to improve asthma medical treatment, the appropriateness of physician prescribing for children with asthma remains unknown. This study measures trends and recent patterns in the pediatric use of medications approved for reversible obstructive airway disease (asthma medications). DESIGN: Population-based longitudinal and cross-sectional analyses. Setting. A nonprofit staff model health maintenance organization located in the Puget Sound area of Washington state. PARTICIPANTS: Children 0 to 17 years of age enrolled continuously during any one of the years from 1984 to 1993 (N = 83 232 in 1993). PRIMARY OUTCOME MEASURES. Percent of enrollees filling prescriptions for asthma medications and fill rates by medication class and estimated duration of inhaled antiinflammatory medication use. RESULTS: Between 1984 and 1993, the frequency of asthma medication use increased: the percent of children filling any asthma medication prescription increased from 4. 0% to 8.1%, whereas the percent filling an inhaled antiinflammatory inhaler rose from 0.4% to 2.4%. In contrast, the intensity of inhaled antiinflammatory use decreased among users; 37% of users filled more than two inhalers during the year in 1984, and 29% in 1993. In high beta-agonist users (filling more than two beta-agonist inhalers each quarter per year), the estimated duration of inhaled antiinflammatory use increased slightly from a mean of 4.1 months per year in 1984-1986 to 5.0 months in 1991-1993; estimated duration of use in adolescents 10 to 17 years of age was approximately half that of children 5 to 9 years of age. CONCLUSIONS: The proportion of children using asthma medications increased substantially during the study period, but the use of inhaled antiinflammatory medication per patient remained low even for those using large amounts of inhaled beta-agonists. These findings suggest that most asthma medications were used by children with mild lower airway symptoms and that inhaled antiinflammatory medication use in children with more severe disease fell short of national guidelines.

Adolescent↗
PubMed1999

Cost and outcomes of Medicare reimbursement for HMO preventive services.

Medicare beneficiaries enrolled in a health maintenance organization (HMO) were randomized to a preventive services benefit package for 2 years or to usual care. At 24- and 48-month follow-ups, the treatment group had completed more advance directives, participated in more exercise, and consumed less dietary fat than the control group. Unexpectedly, more deaths occurred in the treatment group. Surviving treatment-group enrollees reported higher satisfaction with health, less decline in self-rated health status, and fewer depressive symptoms than surviving control participants. Despite these changes, the intervention did not yield lower cost per quality-adjusted life year in this historically prevention-oriented HMO.

Aged↗
PubMed1998

Binding of human IgG and F(ab')2 and Fc fragments to cultured trophoblast cells from human term placenta.

Trophoblast cells, dispersed by trypsin digestion of human term placental villi and purified on Percoll gradient, were maintained in serum-containing medium as monolayer cultures up to 7 days. The initially mononucleated cells, probably cytotrophoblasts, differentiated in culture within 90 h to multinucleated syncytiotrophoblast-like cells. The enigmatic binding of human immunoglobulin G (hIgG) to these cells was studied and compared to the well-known binding of hIgG to cultured human monocytes. Binding of hIgG to cultured trophoblasts at 4 degreesC reached steady state by 0.5-1 h, increased about two- to threefold after 90 h in culture and was linear throughout all concentrations tested (0.00067-132 microM). Fc fragments and even F(ab')2 fragments were found to bind to a similar extent to trophoblasts as the complete hIgG molecules. In contrast, in experiments with cultured monocytes, saturation of hIgG binding could be demonstrated. The binding of complete hIgG molecules and of Fc fragments to monocytes was similar whereas binding of F(ab')2 fragments to monocytes was significantly lower. Our results suggest that, despite morphological and at least partially functional differentiation of trophoblast cells in primary culture, no measurable amounts of functional Fc receptor for monomeric hIgG was expressed.

Binding Sites, Antibody↗
PubMed1998

Predicting hospitalization and functional decline in older health plan enrollees: are administrative data as accurate as self-report?

OBJECTIVE: To compare the predictive accuracy of two validated indices, one that uses self-reported variables and a second that uses variables derived from administrative data sources, to predict future hospitalization. To compare the predictive accuracy of these same two indices for predicting future functional decline. DESIGN: A longitudinal cohort study with 4 years of follow-up. SETTING: A large staff model HMO in western Washington State. PARTICIPANTS: HMO Enrollees 65 years and older (n = 2174) selected at random to participate in a health promotion trial and who completed a baseline questionnaire. MEASUREMENT: Predicted probabilities from the two indices were determined for study participants for each of two outcomes: hospitalization two or more times in 4 years and functional decline in 4 years, measured by Restricted Activity Days. The two indices included similar demographic characteristics, diagnoses, and utilization predictors. The probabilities from each index were entered into a Receiver Operating Characteristic (ROC) curve program to obtain the Area Under the Curve (AUC) for comparison of predictive accuracy. RESULTS: For hospitalization, the AUC of the self-report and administrative indices were .696 and .694, respectively (difference between curves, P = .828). For functional decline, the AUC of the two indices were .714 and .691, respectively (difference between curves, P = .144). CONCLUSIONS: Compared with a self-report index, the administrative index affords wider population coverage, freedom from nonresponse bias, lower cost, and similar predictive accuracy. A screening strategy utilizing administrative data sources may thus prove more valuable for identifying high risk older health plan enrollees for population-based interventions designed to improve their health status.

Activities of Daily Living↗
PubMed1997

Missense mutations abolishing DNA binding of the osteoblast-specific transcription factor OSF2/CBFA1 in cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant disorder characterized by hypoplastic or absent clavicles, large fontanelles, dental anomalies and delayed skeletal development. The phenotype is suggestive of a generalized defect in ossification and is one of the most common skeletal dysplasias not associated with disproportionate stature. To date, no genetic determinants of ossification have been identified. CCD has been mapped to chromosome 6p21, where CBFA1, a gene encoding OSF2/CBFA1, a transcriptional activator of osteoblast differentiation, has been localized. Here, we describe two de novo missense mutations, Met175Arg and Ser191Asn, in the OSF2/CBFA1 gene in two patients with CCD. These two mutations result in substitution of highly conserved amino acids in the DNA-binding domain. DNA-binding studies with the mutant polypeptides show that these amino acid substitutions abolish the DNA-binding ability of OSF2/CBFA1 to its known target sequence. Concurrent studies show that heterozygous nonsense mutations in OSF2/CBFA1 also result in CCD, while mice homozygous for the osf2/cbfa1 mull allele exhibit a more severe lethal phenotype. Thus, these results together suggest that CCD is produced by haploinsufficiency of OSF2/CBFA1 and provide direct genetic evidence that the phenotype is secondary to an alteration of osteoblast differentiation.

Amino Acid Sequence↗
PubMed1997

Health care utilization and cost among children with asthma who were enrolled in a health maintenance organization.

OBJECTIVE: To measure the impact of asthma on the use and cost of health care by children in a managed care organization. DESIGN: Population-based historical cohort study. SETTING: A medium-sized staff model health maintenance organization in western Washington state. SUBJECTS: All 71 818 children, between age 1 to 17 years, who were enrolled and used services during 1992. OUTCOME MEASURES: Children were identified with one or more asthma diagnoses during 1992 using automated encounter data. Nonurgent outpatient visits, pharmacy fills, urgent care visits, and hospital days, as well as associated costs were measured. All services were categorized as asthma care or nonasthma care. Multivariate regression analysis was used to compute marginal cost for asthma (difference in total cost between children with asthma and other children using services, adjusted for covariates). RESULTS: Treated prevalence of asthma was 4.9%. Children with asthma incurred 88% more costs ($1060.32 vs $563. 81/yr), filled 2.77 times as many prescriptions (11.59 vs 4.19/yr), made 65% more nonurgent outpatient visits (5.75 vs 3.48/yr), and had twice as many inpatient days (.23 vs .11/yr) compared with the general population of children using services. Asthma care represented 37% of all health care received by children with asthma, while the remaining 63% were for nonasthma services. Almost two-thirds of asthma-related costs were attributable to nonurgent outpatient care and prescriptions; only one third was attributable to urgent care and hospitalizations. Controlling for age, sex, and comorbidities, the marginal cost of asthma was $615.17/yr (95% confidence interval $502.73, $727.61), which includes asthma as well as nonasthma services. This marginal cost represents 58% of all health care costs for children with asthma. CONCLUSIONS: Children with asthma use significantly more health services (and incur significantly more costs) than other children using services, attributable largely to asthma care. The majority of all health care costs for children with asthma were for nonasthma services. Urgent care visits and hospitalizations are less important components of asthma costs in this managed care organization than has been found in other national studies.

Adolescent↗
PubMed1997

[Cultivated keratinocytes on micro-carriers: in vitro studies of a new carrier system].

Epidermal grafts from confluently cultivated keratinocytes have been used since the early eighties for the treatment of severe burns, where the shortage of donor sites for split-thickness skin grafts did not allow for adequate wound coverage. The difficult handling of these grafts as well as the advanced differentiation of their epithelial cells into a multilayer sheet poses a problem for their clinical application. The aim of the study was to characterize cultivated keratinocytes, as well as to observe their migration and proliferation from the MC onto a surface. Keratinocytes were isolated from human foreskin and cultivated in serum-free and serum-containing medium according to a modified method by Rheinwald and Green. Collagen-coated Dextran beads were used as MC. The MC were colonized with keratinocytes using the Spinner culture technique. After seeding the colonized MC into culture flasks, their migration and proliferation was monitored regularly through immunohistochemical studies and measurement of the metabolic cell activity. Immunohistological staining proved that the cells isolated from human foreskin represent keratinocytes of the basal type. Keratinocytes, cultivated with serum-containing and serum free medium, both adhered to the surface of the MC, then migrated onto the surface of the flasks and proliferated to form a multilayer of epithelial cells. In the long-term, a flexible epithelial graft consisting of poorly differentiated keratinocytes should be available, which is simple to produce and easy to handle. This would be an alternative method for treating wounds, where the conventional multilayer epithelial graft (ET) is insufficient.

Burns↗
PubMed1995

Salt effects on polyelectrolyte-ligand binding: comparison of Poisson-Boltzmann, and limiting law/counterion binding models.

The theory for salt dependence of the free energy, entropy, and enthalpy of a polyelectrolyte in the PB (PB) model is extended to treat the nonspecific salt dependence of polyelectrolyte-ligand binding reactions. The salt dependence of the binding constant (K) is given by the difference in osmotic pressure terms between the reactants and products. For simple 1-1 salts it is shown that this treatment is equivalent to the general preferential interaction model for the salt dependence of binding [C. Anderson and M. Record (1993) Journal of Physical Chemistry, Vol. 97, pp. 7116-7126]. The salt dependence, entropy, and enthalpy are compared for the PB model and one specific form of the preferential interaction coefficient model that uses counterion condensation/limiting law (LL) behavior. The PB and LL models are applied to three ligand-polyelectrolyte systems with the same net ligand charge: a model sphere-cylinder binding reaction, a drug-DNA binding reaction, and a protein-DNA binding reaction. For the small ligands both the PB and limiting law models give (In K vs. In[salt]) slopes close in magnitude to the net ligand charge. However, the enthalpy/entropy breakdown of the salt dependence is quite different. In the PB model there are considerable contributions from electrostatic enthalpy and dielectric (water reorientation) entropy, compared to the predominant ion cratic (release) entropy in the limiting law model. The relative contributions of these three terms in the PB model depends on the ligand: For the protein, ion release entropy is the smallest contribution to the salt dependence of binding. The effect of three approximations made in the LL model is examined: These approximations are (1) the ligand behaves ideally, (2) the preferential interaction coefficient of the polyelectrolyte is unchanged upon ligand binding, and (3) the polyelectrolyte preferential interaction coefficient is given by the limiting law/counterion-condensation value. Analysis of the PB model shows that assumptions 2 and 3 break down at finite salt concentrations. For the small ligands the effects on the slope cancel, however, giving net slopes that are similar in the PB and LL models, but with a different entropy/enthalpy breakdown. For the protein ligand the errors from assumptions 2 and 3 in the LL models do not cancel.

Computer Graphics↗