Activation of erythropoietin receptor in the absence of hormone by a peptide that binds to a domain different from the hormone binding site

Applying a homology search method previously described, we identified a sequence in the extracellular dimerization site of the erythropoietin receptor, distant from the hormone binding site. A peptide identical to that sequence was synthesized. Remarkably, it activated receptor signaling in the absence of erythropoietin. Neither the peptide nor the hormone altered the affinity of the other for the receptor; thus, the peptide does not bind to the hormone binding site. The combined activation of signal transduction by hormone and peptide was strongly synergistic. In mice, the peptide acted like the hormone, protecting against the decrease in hematocrit caused by carboplatin.

Methylphenidate treatment for bulimia nervosa associated with a cluster B personality disorder

OBJECTIVES

Psychotherapy and antidepressant medication are helpful to many patients with bulimia nervosa (BN). However, a substantial number of bulimics respond poorly to such treatments. Recent studies suggest that many of the poor responders have cluster B personality disorders. In some ways, the symptomatology of bulimics who have a comorbid cluster B disorder resembles that of patients with attention deficit hyperactivity disorder (ADHD). In particular, individuals in both groups frequently have a high level of impulsivity. Such a resemblance raised the question of whether administration of methylphenidate (MPH), a drug used to treat ADHD, would have therapeutic effects in this subgroup of BN patients.

METHODS

In a pilot study, we administered MPH to 2 patients with BN and cluster B traits and found beneficial effects. These patients had not responded to adequate trials of psychotherapy and selective serotonin reuptake inhibitors (SSRIs).

RESULTS

MPH treatment was effective. Both Patients had decreased binging and purging.

DISCUSSION

MPH may be useful for bulimics with cluster B personality disorder who respond poorly to conventional treatment. Further studies of MPH administration may be worthwhile. Due to the potential risks, however, clinical treatment with this agent is not recommended at this time.

[Pulmonary infection from Rhodococcus equi after renal transplantation. Review of the literature]

Rhodococcus Equi, a strictly aerobic Gram positive coco-bacillus, is a pathogen for horses and foals. It may induce opportunistic infections and is described in AIDS infected patients. We report the case of a 47-year old man, breeder of horses, with kidney transplant who has presented, 8 years after his graft, an impairment of health, a fever and evidence of pulmonary disease. The pulmonary biopsy under scanner guidance and microbiology study, has displayed the diagnosis of Rhodococcus equi infection. The evolution has been favorable with double antibiotherapy (follow-up 27 months). Ten comparable observations have been published after organ transplantation: (kidney: 8; heart: 1; liver: 1). Pulmonary locations are widely predominant. The animal contact is found only in 30% of cases. The presentation of the sickness has been compared to pulmonary tuberculosis or to nocardiosis, pathologies often observed in this context of immunosuppression. The antibiotic treatment is difficult and should required two bactericidal antibiotics. A surgical lobectomy can be envisaged in case of relapse. The mortality is 30%.

Cux/CDP homeoprotein is a component of NF-muNR and represses the immunoglobulin heavy chain intronic enhancer by antagonizing the bright transcription activator

Nuclear matrix attachment regions (MARs) flanking the immunoglobulin heavy chain intronic enhancer (Emu) are the targets of the negative regulator, NF-muNR, found in non-B and early pre-B cells. Expression library screening with NF-muNR binding sites yielded a cDNA clone encoding an alternatively spliced form of the Cux/CDP homeodomain protein. Cux/CDP fulfills criteria required for NF-muNR identity. It is expressed in non-B and early pre-B cells but not mature B cells. It binds to NF-muNR binding sites within Emu with appropriate differential affinities. Antiserum specific for Cux/CDP recognizes a polypeptide of the predicted size in affinity-purified NF-muNR preparations and binds NF-muNR complexed with DNA. Cotransfection with Cux/CDP represses the activity of Emu via the MAR sequences in both B and non-B cells. Cux/CDP antagonizes the effects of the Bright transcription activator at both the DNA binding and functional levels. We propose that Cux/CDP regulates cell-type-restricted, differentiation stage-specific Emu enhancer activity by interfering with the function of nuclear matrix-bound transcription activators.

The two-dimensional histogram as a constraint for protein phase improvement

The joint distribution of electron density and its gradient in a protein electron-density map was examined. This joint distribution was represented by a two-dimensional histogram (2D histogram) of electron-density values and the modulus of the gradient. 16 structures representing distinct protein-fold families were selected to study the dependence of the 2D histogram on resolution, overall temperature factor, structural conformation and phase error. The similarity between the histograms for a pair of structures was measured by correlation coefficient, and the residual provided a measure of the difference. The 2D histogram was found to vary with resolution and overall temperature factor, but was found to be insensitive to structure conformation. The average correlation coefficient between pairs of 2D histograms at three different resolutions examined was 0.90 with a standard deviation of 0.04. The average residual for the same condition was 0.13 with a standard deviation of 0.03. The 2D histogram was also found to be sensitive to phase error. The average correlation coefficient and residual between 2D histograms with 10 degrees phase difference are 0.71 and 0.18, respectively. The variation of the 2D histogram resulting from structure-conformation changes was estimated to be equivalent to that of a 4 degrees phase error. This establishes the minimal phase error that a 2D histogram-matching method could achieve. The conservation of the 2D histogram with respect to structure conformation enables the prediction of the ideal 2D histogram for unknown structures. The sensitivity of the 2D histogram to phase error suggests that it could be used as a target for the density-modification method and also could be used as a figure of merit for phase selection in ab initio phasing.

A comparison of forensic and nonforensic malingerers: a prototypical analysis of explanatory models

Explanatory models of malingering strive to understand the primary motivation underlying attempts to feign. Rogers, Sewell, and Goldstein (1994) provided empirical support for the conceptualization of pathogenic, criminological, and adaptational models. In the current study, a prototypical analysis of 221 forensic experts results in a slightly refined formulation: the adaptational models was decomposed into its two broad dimensions (cost-benefit analysis and adversarial setting). An important findings is that the factor structure for the explanatory models remained stable when applied to both forensic and nonforensic cases. As a first investigation, significant differences were observed in prototypical cases of malingering by the category of referral (forensic or nonforensic) and by type of feigning (mental disorders, cognitive impairment, and medical syndromes). Surprisingly, the feigning of medical syndromes appeared to play a relatively prominent role in both forensic and nonforensic cases and to be influenced by the apparent adversarial context of the assessment. Finally, important gender differences were observed, especially with nonforensic prototypical cases of malingering.

Correlation of color Doppler flow in the prostate with tissue microvascularity

BACKGROUND

The pathophysiology of increased color Doppler (CD) flow has not previously been addressed in histologic evaluations of microvascular parameters. In this study, the authors attempted to define the differences between benign and malignant biopsy cores found in regions of the prostate with normal and high CD flow.

METHODS

Forty patients were retrospectively chosen for CD histologic comparison, each of whom had a core from a sextant biopsy with the following characteristics: malignant tissue with distinct increased CD flow (n=11), malignant tissue with normal CD flow (n=10), benign tissue with distinctly increased CD flow (n=9), or benign tissue with normal CD flow (n=10). All biopsy cores were stained with factor VIII-related antigen to identify microvasculature and to determine the number of microvessels per square millimeter (mm2) in an average cross-sectional area of microvessels, the percentage of tissue occupied by microvasculature, and the Gleason score.

RESULTS

In biopsies of benign tissue, high CD flow was associated with greater numbers (P < 0.025) of vessels of similar size than in normal flow benign biopsies. Biopsies of malignant tissue contained significantly greater numbers (P < 0.01) of much smaller vessels (P < 0.0005) than biopsies of benign tissue. In biopsies of malignant tissue, no significant differences in microvasculature parameters were noted between high and normal CD flow, yet biopsies with high CD flow had average Gleason score of 6.7 compared with only 5.9 for biopsies with normal CD flow (P < 0.025).

CONCLUSIONS

Increased CD flow in biopsies of benign tissue was correlated with a greater number of vessels/mm2, yet all biopsies of malignant tissue had more vessels/mm2 than those of benign tissue. Increased CD flow in biopsies of malignant tissue cannot be explained by standard microvasculature analysis but significantly guides biopsies to regions with a greater Gleason score.

Panoramic radiology quality assessment

A procedure is proposed for performing noninvasive x-ray quality assessment tests on panoramic radiology equipment. A simple cardboard tube jig eliminates relative motion between the measurement system and the narrow, collimated x-ray beam. Accurate measurements of beam HVL, x-ray exposure coefficient of variation and mA linearity may be obtained. Use of the tube jig permits easy and routine monitoring of these important x-ray parameters as well as consistency checks of tube output. Film/screen contact also should be routinely checked in the clinic.

Exposure and dose in panoramic radiology

Panoramic radiology entrance skin exposure (ESE) was measured for a Siemens Orthopantomograph 10 E using a thimble chamber and TLDs. Thimble chamber measurements are shown to be inaccurate for the moving, narrow beam panoramic scan geometry due to partial volume and partial charged-particle equilibrium effects. For 75 KVp, 8 mA panoramic scans the TLD measured beam central ray ESE on the scan central plane (patient midsagittal plane) was an approximately constant 20 mR for the first 7.5 cm from the entrance slit. A theoretical model of central plane ESE for a fixed rotation center agrees very well with the TLD measurements and is consistent with all of the known ESE (and dose) properties near rotation centers. Head phantom skin dose measurements demonstrate the dependence of skin dose on exact equipment mode of use and patient anatomy. Central plane, beam central ray ESE is judged to be a convenient, universal measure of panoramic radiology radiation output.

Radiation exposure during skeletal traction treatment of pediatric femoral fractures

Radiation-exposure data during femoral fracture management has not been previously reported. We report a retrospective analysis of radiation exposure in 45 patients aged 5-12 years (average, 8.3) with isolated femoral shaft fractures treated by 90/90 degrees femoral skeletal traction. Group I had 32 patients aged 5-9 years (average, 7.3), and group II had 13 patients of an average age of 10.7 years. Total average radiation dose before casting was 0.699 rads and was independent of age and gender. In addition to potential complications of tractions and increased hospital stay with attendant fiscal and psychosocial burdens, radiation exposure with this type of management, in this series, was significant.

Diffraction effects in hydrophone measurements

Theoretical and experimental methodology are presented for accurately determining the effective radii of unfocused, circular plane piston transducers as well as using tone burst hydrophone measurements to verify steady-state theoretical calculations. Experiments using two specially fabricated unfocused, composite piezoelectric transducers demonstrate the validity of the methodology. For spherically focused circular transducers, a simple model is used to estimate the transient diffraction encountered in co-axial flat hydrophone measurements.

Issues involving biomarkers in the study of the genetics of human cancer

The investigation of hereditary factors in human cancer was suggested from kindreds that exhibited aggregations of cancer consistent with Mendelian inheritance. A subset of cancer that exhibits strong familial tendencies is due to single genes that 'cause' cancer; more commonly, hereditary factors may influence tumorigenesis in a stepwise probabilistic rather than deterministic manner through a variety of mechanisms, e.g. influencing the disposition of carcinogens. The roles of both common susceptibility genes and rare 'familial' cancer genes are receiving increasing attention in the general population. Population-based studies designed to examine more common genetic variants differ from linkage-based studies. Candidate susceptibility genes may be studied by phenotype or genotype approaches, and the relative advantages and disadvantages of each approach are considered. The issue of gene-environment interaction, implicit in the concept of susceptibility genes, is considered. The influence of genetic factors on individual and attributable risk is addressed.

Caffeine dependence in schoolchildren?

Schoolchildren (N = 289) kept a log and calculated their habitual caffeine consumption (principally in soft drinks). On 2 successive days, they completed a 20-item checklist adapted from the Profile of Moods Scale. On Day 2, they abstained from caffeine. Complete data were obtained for 175 children. A low-consumption group (10 mg or less daily) was compared with a high-consumption group (50 mg or more daily). The high-consumption group reported more stimulation than did the low-consumption group on Day 1 and more dysphoric symptoms during abstinence on Day 2. The results of this open-label pilot trial suggest that a large-scale double-blind placebo-controlled trial would be worthwhile.

Migration, fertility, and state policy in Hubei Province, China

Despite China's one-child family planning policy, the nation experienced a slight rise in the birth rate in the mid-1980s. Many observers attributed this rise to the heightened fertility of those rural-to-urban migrants who moved without a change in registration (temporary migrants), presumably to avoid the surveillance of family planning programs at origin and destination. Using a sequential logit analysis with life-history data from a 1988 survey of Hubei Province, we test this possibility by comparing nonmigrants, permanent migrants, and temporary migrants. While changing family planning policies have a strong impact on timing of first birth and on the likelihood of higher-order births, migrants generally do not have more children than nonmigrants. In fact, migration tends to lower the propensity to have a child. More specifically, the fertility of temporary migrants does not differ significantly from that of other women.

A peptide derived from an extracellular domain selectively inhibits receptor internalization: target sequences on insulin and insulin-like growth factor 1 receptors

Certain peptides derived from the alpha1 domain of the major histocompatibility class I antigen complex (MHC-I) inhibit receptor internalization, increasing the steady-state number of active receptors on the cell surface and thereby enhancing the sensitivity to hormones and other agonists. These peptides self-assemble, and they also bind to MHC-I at the same site from which they are derived, suggesting that they could bind to receptor sites with significant sequence similarity. Receptors affected by MHC-I peptides do, indeed, have such sequence similarity, as illustrated here by insulin receptor (IR) and insulin-like growth factor-1 receptor. A synthetic peptide with sequence identical to a certain extracellular receptor domain binds to that receptor in a ligand-dependent manner and inhibits receptor internalization. Moreover, each such peptide is selective for its cognate receptor. An antibody to the IR peptide not only binds to IR and competes with the peptide but also inhibits insulin-dependent internalization of IR. These observations, and binding studies with deletion mutants of IR, indicate that the sequence QILKELEESSF encoded by exon 10 plays a key role in IR internalization. Our results illustrate a principle for identifying receptor-specific sites of importance for receptor internalization, and for enhancing sensitivity to hormones and other agonists.

Lack of phospholipase A2 mutations in neuroblastoma, melanoma and colon-cancer cell lines

A candidate murine tumor-suppressor gene, Mom1, has been identified as the secretory phospholipase A2 (GDB nomenclature: PLA2G2A) gene. Evidence suggests that PLA2G2A functions as a tumor-suppressor because mice lacking PLA2G2A expression demonstrate increased colonic polyposis. The human homologue of PLA2G2A has been mapped to chromosome 1p36, a region frequently implicated in the pathogenesis of neuroblastoma, colon cancer and melanoma. We identified 2 alterations in the PLA2G2A gene in a single neuroblastoma cell line out of 20 examined; however, we found no mutations in 24 melanoma cell lines, 12 lymphoblastoid cell lines from patients having chromosome 1-linked familial melanoma and 10 colon cancer cell lines. Secretory phospholipase A2 is unlikely to play a significant role in the pathogenesis of these tumors.

Characterization of a YAC contig containing the NBCCS locus and a novel Kruppel-type zinc finger sequence on chromosome segment 9q22.3

Gorlin's syndrome or nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by a familial or hereditary predisposition to basal cell carcinomas (generally multiple and of early onset), odontogenic keratocysts (jaw cysts), palmar and plantar pits, a wide variety of developmental defects, as well as cancers such as medulloblastomas and ovarian fibromas. The gene for NBCCS has been mapped to human chromosome region 9q22.1-q31 by linkage analysis and by cytogenetic evidence of deletions in this region in patients with the syndrome. This is supported by loss of heterozygosity in tumors of polymorphic marker loci flanked by D9S197 and D9S180. We have utilized sequence tagged site (STS) mapping and somatic cell hybrid panel analysis to construct two overlapping yeast artificial chromosome (YAC) contigs spanning this region of the genome. We used the YAC contigs to identify a new zinc finger gene containing a highly informative microsatellite locus.

Imaging of pelvic postpartum complications

Differentiation between endometritis and RPOC in febrile postpartum patients is commonly requested by clinicians. Sonography is the screening technique of choice to assess the endometrial contents. For cases in which the retained placenta is calcified or still has demonstrable blood flow, a specific diagnosis of RPOC can be made. In more complicated cases, a CT scan or an MR image may be requested. In addition to evaluating the uterus and any intra- or extrauterine fluid collections, attention must be paid to the ovarian veins to exclude the diagnosis of ovarian vein thrombosis.

Molecular analysis of chromosome 9q deletions in two Gorlin syndrome patients

Gorlin syndrome is an autosomal dominant disorder characterized by multiple basal cell carcinomas, medulloblastomas, ovarian fibromas, and a variety of developmental defects. All affected individuals share certain key features, but there is significant phenotypic variability within and among kindreds with respect to malformations. The gene (NBCCS) maps to chromosome 9q22, and allelic loss at this location is common in tumors from Gorlin syndrome patients. Two recessive cancer-predisposition syndromes, xeroderma pigmentosum group A (XPAC) and Fanconi anemia group C (FACC), map to the NBCCS region; and unusual, dominant mutations in these genes have been proposed as the cause of Gorlin syndrome. This study presents cytogenetic and molecular characterization of germ-line deletions in one patient with a chromosome 9q22 deletion and in a second patient with a deletion of 9q22-q3l. Both have typical features of Gorlin syndrome plus additional findings, including mental retardation, conductive hearing loss, and failure to thrive. That Gorlin syndrome can be caused by null mutations (deletions) rather than by activating mutations has several implications. First, in conjunction with previous analyses of allelic loss in tumors, this study provides evidence that associated neoplasms arise with homozygous inactivation of the gene. In addition, dominant mutations of the XPAC and FACC1 genes can be ruled out as the cause of Gorlin syndrome, since the two patients described have null mutations. Finally, phenotypic features that show variable expression must be influenced by genetic background, epigenetic effects, somatic mutations, or environmental factors, since these two patients with identical alterations (deletions) of the Gorlin syndrome gene have somewhat different manifestations of Gorlin syndrome.

Increased urinary nitrite excretion in children with minimal change nephrotic syndrome

OBJECTIVE

We tested the hypothesis that nitric oxide synthesis by the kidney is increased in children with primary nephrotic syndrome.

METHODS

We examined the urinary excretion of nitrite, a stable metabolite of nitric oxide, using the Griess reaction, in children with nephrotic syndrome.

RESULTS

In comparison with healthy children, patients with minimal change nephrotic syndrome had increased urinary nitrite excretion regardless of whether the disease was in relapse or remission (p < 0.025). In contrast, urinary nitrite excretion was similar in control subjects and patients with focal segmental glomerulosclerosis or IgA nephropathy.

CONCLUSION

These findings indicate that measurement of urinary nitrite excretion may be a useful test to help discriminate between minimal change nephrotic syndrome and focal segmental glomerulosclerosis in children with idiopathic nephrotic syndrome.

Heroin addicts and methadone treatment in Albuquerque: a 22-year follow-up

All heroin addicts who registered for methadone treatment in Albuquerque in 1969-1971, 1019 in all, were the subjects of this follow-up study, conducted in 1991-1993. The cohort was almost entirely of Hispanic (Chicano) ethnicity, 86% male, with median age 27 at entry. We located 776, dead or alive, and we were able to interview 243 concerning many aspects of their lives. At least one-third of the original group had died during the 22-year period, representing standard mortality ratios 4.0 for males and 6.8 for females. Drug overdose, violence, alcohol, or suicide accounted for nearly all deaths of which the causes were known. Despite the availability of treatment, including methadone maintenance, both heroin use and criminality continued at a high rate. Of the 428 known survivors, 48% were currently enrolled in a methadone program after 22 years. They were using significantly less heroin, alcohol, and other drugs (except nicotine) than those not on methadone. Similar beneficial effects of methadone maintenance were reported retrospectively at interview. Our findings offer an insight into heroin addiction as a chronic lifelong relapsing disease with a high fatality rate.

What does it mean to be a cancer gene carrier? Problems in establishing causality from the molecular genetics of cancer

This article addresses the following question: What does it mean to be a cancer gene carrier? The existence of families prone to cancer has prompted an intense search for predisposing heritable gene mutations. Genes that impart susceptibility to colorectal, breast, and ovarian cancers have been recently identified. It is doubtful, however, that the action of a single mutant gene totally accounts for the development of malignant disease. The mutant gene likely causes cancer in these family members only in conjunction with other genes, environmental factors, or both. Furthermore, although an individual carrier of a mutant gene within a cancer-prone family has an increased risk of malignancy, nutritional, pharmacologic, or other interventions may still confer protection. Extrapolations from cancer-prone families to the general population are even more problematic. The excess risk of malignancy among carriers of mutant genes who are not members of cancer-prone families is unknown. Large-scale epidemiologic studies are needed to determine the magnitude (or even the existence) of such excess risk.

Training pediatric residents to prevent tobacco use

OBJECTIVE

To assess the effectiveness and acceptability of incorporating the National Cancer Institute (NCI) Guide to Preventing Tobacco Use During Childhood and Adolescence into pediatric training.

DESIGN

Preintervention and postintervention self-reported surveys for residents receiving training and postintervention baseline surveys for those residents not receiving training. Measures include: (1) a self-reported knowledge, attitude, and behavior survey of residents; and (2) physician behavior reports from parent exit interviews.

SETTING

A hospital-based pediatric residency program and continuity clinic.

SUBJECTS

Pediatric residents and parents of pediatric patients seen for well child examinations.

INTERVENTIONS

Structured NCI smoking cessation curriculum modified for delivery during scheduled teaching activities.

RESULTS

The NCI training was acceptable and perceived as important by residents. Many did not recall receiving the materials or training. Trained residents who remembered the intervention improved their smoking cessation counseling effectiveness. Most patients' parents think it appropriate for physicians to ask; however, most reported not having been asked about smoking or environmental smoke exposure.

CONCLUSIONS

For residents to learn effective prevention counseling strategies, systematic, reinforced preventive educational curricula must become an institutionalized part of residency training.

Cancer genes: single and susceptibility: exposing the difference

'Single' genes, necessary and sufficient to cause cancer, are contrasted with 'susceptibility' genes that are neither, but may act in the presence of specific environmental exposures to alter the chances of cancer in the host. The former are rare, are of high absolute and relative risks, have minimal dependence on exposures and therefore have low population attributable risks. A small number of such genes are well established in the literature and typically exhibit familial aggregations of disease that serve as a starting point for genetic studies. 'Susceptibility' genes, as typified by the pharmacogenetic model, are common, have low relative and absolute risk, are strongly dependent upon exposure, and may have potentially high population attributable risks. Mechanistic and epidemiologic data are suggestive but currently fall short of confirmation for these associations. Familial aggregation is not a prominent feature and epidemiological study designs with careful exposure assessment is the investigative method of choice. Both approaches require interdisciplinary expertise and benefit from advances in molecular biology.

Somatostatin levels during infancy, pregnancy, and lactation: a review

This paper reviews research on somatostatin (SS) levels during infancy, pregnancy, and lactation. Neonates have elevated levels of circulating SS, which reach a peak at the age of 3 months and then decrease gradually, but remain elevated during the first years of life. SS response to feeding is not well developed in newborns. Elevated levels are also found during pregnancy, especially during the late phases. Influence of sucking on maternal SS plasma levels is varied and could be related to vagal stimulation. pH levels, and basal SS levels. SS has been found in high concentrations in maternal milk. Milk-borne SS appears to be protected from proteolysis by milk components, but apparently SS is not absorbed in its intact form through the duodenal wall and its effects could be indirect. More research is needed to determine the regulating role of milk-borne SS and the contribution of SS to development.

Romanticism and self-esteem among pregnant adolescents, adolescent mothers, and nonpregnant, nonparenting teens

Feelings of romanticism and self-esteem among pregnant adolescents, adolescent mothers, and a control group of nonpregnant, nonparenting adolescents were investigated. The Bachman Self-Esteem Scale (Bachman, O'Malley, & Johnston, 1978) and the Dean Romanticism Scale (Dean, 1961) were distributed to 649 U.S. female adolescents--255 pregnant adolescents, 121 adolescent mothers, and 273 teenagers in the control group. For romanticism, the results indicated a significant main effect for group (pregnant teens, teen mothers, and a control group consisting of nonpregnant, nonparenting teenagers) and ethnicity (White, Hispanic, African American, and Asian) but not for age (13 to 15 years and 16 to 19 years). The pregnant teens and teen mothers thus had a higher degree of romanticism than the control group did. For self-esteem, there was a significant main effect for race, but not for group or for age. This main effect was qualified by a significant interaction between ethnicity and age.

Regulation of receptor internalization by the major histocompatibility complex class I molecule

We showed previously that peptides derived from the alpha 1 domain of the major histocompatibility complex class I protein (MHC-I) inhibit internalization of some receptors, thereby increasing the steady-state number of active receptors on the cell surface. In consequence, sensitivity to hormone (e.g., insulin) is enhanced, transport (e.g., of glucose by GLUT-4) is increased, and carrier proteins (e.g., transferrin) operate less efficiently. Now we report that a bioactive peptide (but not closely related inactive ones) binds to MHC-I on the cell surface, not in the groove but apparently to the alpha 1 helix. The binding is saturable, and the number of peptide binding sites on the cell surface approximately equals the number of MHC-I molecules. Antibodies to MHC-I inhibit peptide binding. Most significant, antibodies to MHC-I mimic the effect of a bioactive peptide, inhibiting receptor internalization. These results indicate that MHC-I participates in the regulation of cell surface receptor activity.

Primary structure and functional expression of a guinea pig kappa opioid (dynorphin) receptor

A full-length cDNA encoding the guinea pig kappa opioid (dynorphin) receptor has been isolated. The deduced protein contains 380 aa and seven hydrophobic alpha-helices characteristic of the G protein-coupled receptors. This receptor is 90% identical to the mouse and rat kappa receptors, with the greatest level of divergence in the N-terminal region. When expressed in COS-7 cells, the receptor displays high affinity and stereospecificity toward dynorphin peptides and other kappa-selective opioid ligands such as U50, 488. It does not bind the mu- and delta-selective opioid ligands. The expressed receptor is functionally coupled to G protein(s) to inhibit adenylyl cyclase and Ca2+ channels. The guinea pig kappa receptor mRNA is expressed in many brain areas, including the cerebellum, a pattern that agrees well with autoradiographic maps of classical guinea pig kappa binding sites. Species differences in the pharmacology and mRNA distribution between the cloned guinea pig and rat kappa receptors may be worthy of further examination.

Detection of rectal antibodies to HIV-1 by a sensitive chemiluminescent western blot immunodetection method

Western blot with a time-dependent enhanced chemiluminescence immunodetection method (ECL-WB) was shown to be 100-fold more sensitive than standard commercial colorimetric Western blots (WB) for detecting serum IgG to human immunodeficiency virus type 1 (HIV-1). ECL-WB was then used to test rectal secretions from 15 HIV-1 infected subjects (HIV+) and 7 uninfected subjects (HIV-) to document local IgG, IgA, and secretory component-associated immunoglobulin (SC-Ig) to HIV-1 proteins. Fourteen of 15 HIV+ subjects had rectal IgA to at least 1 HIV-1 protein, most often to gp41 (80%) or p24 (60%) and 14 (93%) had IgG to gp160, gp120, or gp41. Of seven HIV- subjects, none had detectable bands to HIV-1 proteins. SC-Ig to HIV-1 proteins was detected in all five rectal samples tested. However, the antibody profiles differed from those of rectal IgA, suggesting more than one source of rectal IgA to HIV. ECL-WB requires individual optimization and interpretation for each specimen as well as expensive reagents and is, therefore, not currently applicable to screening assays. However, the method offers promise as a sensitive method to characterize low-level immune responses (IgG, IgA, and SC-Ig) to HIV-1 proteins at local sites such as rectal mucosae.

Correlation between insulin receptor occupancy and tyrosine kinase activity at low insulin concentrations and effect of major histocompatibility complex class I-derived peptide

In rat adipocytes, insulin dose-response curves were determined for the following effects in the same cells under the same conditions: glucose uptake, binding to insulin receptors (IR), IR autophosphorylation in vivo and in vitro, IR tyrosine kinase activity and insulin-stimulated phosphatidylinositol (PI) kinase. All the EC50 values were essentially the same (mean +/- S.E.M. was 7 +/- 1 nM), except for glucose uptake, which was 170 pM. Using an improved method, we were able to measure PI kinase activity at picomolar concentrations of insulin (> 30 pM) corresponding to the EC50 for glucose uptake. These experiments showed that insulin-stimulated increase in glucose uptake was associated with an increase in antiphosphotyrosine antibody precipitable PI kinase activity, consistent with the view that IR tyrosine kinase activity may be involved in insulin-mediated signaling of glucose uptake. Small peptides (17-25 residues long) derived from major histocompatibility complex class I have previously been shown to inhibit IR internalization without any effect on the affinity of insulin to the receptor. It is now shown that the peptide-mediated inhibition of internalization, which doubles the number of insulin-occupied receptors at an insulin concentration of 70 pM, also results in a corresponding enhancement of PI kinase activity and glucose uptake. Thus, the receptors arrested on the cell surface by the peptide are biologically active.

Cloning and pharmacological characterization of a rat kappa opioid receptor

A full-length cDNA was isolated from a rat striatal library by using low-stringency screening with two PCR fragments, one spanning transmembrane domains 3-6 of the mouse delta opioid receptor and the other unidentified but homologous to the mouse delta receptor from rat brain. The novel cDNA had a long open reading frame encoding a protein of 380 residues with 59% identity to the mouse delta receptor and topography consistent with a seven-helix guanine nucleotide-binding protein-coupled receptor. COS-1 cells transfected with the coding region of this clone showed high-affinity binding to kappa opioid receptor-selective ligands such as dynorphin A and U-50,488 and also nonselective opioid ligands such as bremazocine, ethylketocyclazocine, and naloxone. Not bound at all (or bound with low affinity) were dynorphin A-(2-13), enantiomers of naloxone and levophanol [i.e., (+)-naloxone and dextrorphan], and selective mu and delta opioid receptor ligands. Activation of the expressed receptor by kappa receptor agonists led to inhibition of cAMP. Finally, in situ hybridization revealed a mRNA distribution in rat brain that corresponded well to the distribution of binding sites labeled with kappa-selective ligands. These observations indicate that we have cloned a cDNA encoding a rat kappa receptor of the kappa 1 subtype.

Instrumentation of digital gray-scale US

Modern, high-resolution, gray-scale, ultrasound (US) imaging equipment is computer based, with all hardware signal processing functions under software control. This systems architecture permits maximum flexibility in function, rapid upgrades, and reliable performance. With modern US equipment, the spatial dimensions of the analog image are transformed into a digital matrix of picture elements (pixels). The volume of tissue, or voxel, that contributes to the echo amplitudes received from each pixel depends crucially on the section (ie, "slice") thickness at the voxel depth. Partial volume effects are more likely to occur in a longer voxel located at a depth outside the section thickness focal zone. The echo signal voltage, or amplitude, is acquired by an analog-to-digital converter simultaneously with the pixel location of the image echo origin. The most accurate echo amplitudes (with least partial volume averaging) occur at the highest image magnification when the voxel dimensions are the smallest in and out of the scan plane. With computer-based imaging, postprocessing procedures, such as fill-in algorithms and digital calipers (measurements of distances in images), can be used to aid in diagnosis.

Primary care physicians' views on access and health care reform: the situation in North Carolina

BACKGROUND

This cross-sectional study assessed physicians' satisfaction with the current insurance-based reimbursement system and preferences for the two most frequently discussed health care reform proposals, and estimated the association between demographic and practice characteristics and attitudes toward health policy issues and reform plans.

METHODS

A random sample of 300 physicians was drawn from state licensure files of general practitioners, family physicians, and pediatricians practicing in North Carolina. All sample physicians were sent a schematic outline of the two major health reform alternatives and a 1-page self-administered questionnaire to determine their attitudes toward the current health care system and their preferences for health reform alternatives.

RESULTS

Sixty-nine percent of physicians responded to the survey. The responses indicated dissatisfaction with the current system and strong beliefs that access to care is inadequate in this diverse state with a large poor and rural population. Nearly one third of the physicians reported having insufficient information to choose between plans. Among physicians expressing a preference, 37% preferred managed competition, 38% preferred continuing the current system, and 25% preferred a single-payer system.

CONCLUSIONS

A uniform opinion about health care policy is a thing of the past for American medicine. Because terms used in the health reform debate (especially "managed competition") are ambiguous and set in the context of an increasingly diverse medical profession, no single direction of health reform (much less a specific plan) secures widespread understanding or support from a large proportion of physicians. None of the plans will please all of the doctors all of the time.

Chronic granulomatous disease presenting in childhood with Pseudomonas cepacia septicaemia

Two children who presented with fever, enlarged liver and spleen and ascites were found to have Pseudomonas cepacia septicaemia which proved fatal despite appropriate antibiotics and maximum supportive care. Chronic granulomatous disease of childhood (CGD) was subsequently diagnosed in both children. The possibility of CGD needs to be considered in any child with unexplained P. cepacia infection.

Amino acid residues essential for biological activity of a peptide derived from a major histocompatibility complex class I antigen

The stimulatory activity of peptides from the alpha 1 domain of the major histocompatibility complex (MHC) class I antigen on adipose cell glucose transport was previously shown to require a preformed, ordered conformation of the peptide. The two peptides studied previously were Dk-(61-85) (ERETQIAKGNEQSFRVDLRTLLRYY) and Dk-(69-85). We now show that systematic alanine substitution in Dk-(69-85) identifies residues that are essential for biological activity. Ordered structure of the peptides, estimated by circular dichroism, was found in all peptides with activity, but with a complex variety of spectra. Inactive peptides were in either a random coil or an ordered structure. Ordered structure, therefore, is not sufficient for activity. The peptides self-interact in the absence of cells and form aggregates that precipitate upon centrifugation. The tendency to aggregate is correlated with biological potency. Only MHC class I molecules have significant homology to the peptides studied here. The peptide self-interaction suggests that the biological effects in cells, which result from inhibition of receptor and transporter internalization, may be due to the binding (tantamount to self-interaction) of the peptide to the homologous sequences in the alpha 1 domain of the MHC class I molecule.

Overview of the physics of US

In ultrasonography (US), high-frequency sound waves are transmitted through the body by a transducer. When a transmitted ultrasound pulse encounters a tissue target, some of its energy is deflected back to the transducer. The time of flight of this ultrasound echo is used to calculate depth of the target in the transducer beam. The pulse-echo parameters used in the formation of images include echo amplitude, target spatial position, and frequency shift between the transmitted pulse and the received echo. The first two are displayed in gray-scale images and all three in color flow images. In gray-scale US, echo amplitude is encoded into shades of gray, with the lighter shades representing higher amplitude echoes. In color flow US, velocity of moving blood is usually presented in blue for motion toward the transducer and in red for motion away from it. A Doppler spectrum depicts changing blood velocity as a function of time. US has become more clinically valuable due to its ability to demonstrate soft-tissue structures, real-time imaging capability, relative safety, portability, and cost-effectiveness.

Cancer associated haemolytic uraemic syndrome developing prior to treatment with cytotoxic agents

The haemolytic uraemic syndrome has been reported in children and adults with neoplasias treated with mitomycin C and occasionally in adults prior to chemotherapeutic treatment, but it has not been reported in a child prior to the use of cytotoxic drugs. This case report concerns the development of the haemolytic uraemic syndrome in a 7-year-old male child with a metastatic hepatocellular carcinoma. The child had persisting haemolysis and renal impairment, and died three weeks after presentation. Though our experience with similar tumours suggested the outlook would be poor, we had hoped to provide palliative chemotherapy. This proved impossible as optimal chemotherapy could not be used because of the renal impairment.

Expression cloning of cDNA encoding a seven-helix receptor from human placenta with affinity for opioid ligands

Here we report the expression cloning of cDNA encoding a putative opioid receptor from a human placenta cDNA library. Placental opioid receptors are of the kappa type. As the dynorphin opioid peptides are kappa-selective, a dynorphin ligand was used in an affinity-enrichment (panning) procedure to select transiently transfected COS-7 cells expressing kappa receptor binding sites. The cloned cDNA encodes a 440-residue protein of the seven-helix guanine nucleotide-binding protein (G-protein)-coupled receptor family. Ligand binding reveals a stereospecific site with typical opioid properties, which binds peptide and nonpeptide opioids with moderate affinity (Kd approximately 100 nM) and which lacks the expected kappa selectivity. The deduced transmembrane domain is 93% identical to the homologous region of the human neuromedin K (neurokinin B) receptor, but the N-terminal and C-terminal sequences have many dissimilarities. The expressed receptor binds opioid ligands but not tachykinins; and under the same conditions, a cloned rat neuromedin K receptor binds tachykinins but not opioids.