Biomedical subjects
Publications and source records attributed to R A Martin.
Maternal uniparental disomy for the complete long arm of chromosome 14 has been reported in 14 patients to date and is associated with a specific pattern of malformation. We report a child with clinical features of this syndrome who exhibits maternal uniparental disomy confined to a specific interstitial segment of chromosome 14.
Among the major cardenolides from the milkweed Asclepias asperula, 6'-O-(E-4-hydroxycinnamoyl) desglucouzarin has not been characterized biochemically. In this study, its binding affinity for a physiological receptor, porcine kidney Na+,K+-ATPase, was found to be lower than the other cardenolides in this plant. The order of affinities from highest to lowest was: uzarigenin (Kd = 1.05 microM) = desglucouzarin (Kd = 0.98 microM) > uzarin (Kd = 4.0 microM) > 6'-O-(E-4-hydroxycinnamoyl) desglucouzarin (Kd = 16 microM). The chemical attachment of the 4-hydroxycinnamoyl group to the 6'-carbon of desglucouzarin significantly inhibits binding. This agrees with predictions that a 5'-methyl group on cardenolides fits the receptor site optimally for the porcine kidney enzyme. The 4-hydroxycinnamic ester was also found to be fluorescent.
A HPLC method is described for the analysis of ochratoxin A at low-ppb levels in samples of artificially contaminated cocoa beans. The samples are extracted in a mixture of methanol-water containing ascorbic acid, adjusted to pH and evaporated to dryness. Samples in this state are then placed onto a Benchmate sample preparation workstation where C18 solid-phase extraction operations are performed. The resulting materials are evaporated to dryness and analyzed by reversed-phase HPLC with fluorescence detection. The method was evaluated for accuracy and precision with R.S.D.s for multiple injections of sample and standard calculated to 1.1% and 2.5% for sample and standard, respectively. Recoveries of ochratoxin A added to cocoa beans ranged from 87-106% over the range of the assay.
The upper lip of 17 consecutive individuals with various forms of holoprosencephaly were examined either at autopsy or during clinical evaluation. A total of 88% of cases were missing the superior labial frenulum regardless of the severity of holoprosencephaly or other associated craniofacial defects. Because the frenulum was found to be missing across a complete clinical spectrum of holoprosencephaly including cases exhibiting only minimal craniofacial features, it should be inspected as part of the craniofacial examination, and its absence should be prompt imaging studies of the brain. Absence of the frenulum in holoprosencephaly also provides evidence that its embryonic origin is that of the medial nasal process.
The metabolism of ceftiofur in bovine kidney, liver, muscle and lung, and the effects of the presence of cystine and glutathione in the media were evaluated using S-9 and microsomal tissue fractions. Conversion of ceftiofur to desfuroylceftiofur (DFC) was catalyzed by an esterase which was most active in kidney, followed by liver. It was not very active in muscle and lung. After DFC was liberated, it rapidly bound primarily to tissue proteins (> 56%), and was also conjugated to cysteine and glutathione. Production of DFC-cysteine by disulfide exchange of DFC with cystine and production of DFC-glutathione by conjugation of DFC to glutathione occurred in buffer if glutathione and cystine were present in the medium. These conjugations were also observed in incubations with tissue fractions, indicating that they were not inhibited by the tissues endogenous molecules. In addition, the metabolism of DFC-glutathione to DFC-cysteine was observed when tissue proteins were present. The metabolism of DFC-glutathione to DFC-cysteine was faster in kidney than in liver. Metabolites devoid of an intact beta-lactam ring were not observed in these in vitro studies.
OBJECTIVE: The authors investigated the theoretical and clinical role of depression among cocaine abusers in treatment. METHOD: Eighty-nine cocaine-abusing patients underwent 2 weeks of substance abuse treatment. Posttreatment major depressive disorder, depressive symptoms before and after substance abuse treatment, and alcohol diagnoses were assessed and their relation to pretreatment substance use, cravings in high-risk situations, and 3-month follow-up status was examined. RESULTS: High rates of major depressive disorder were found but were unrelated to pretreatment substance use. The decrease in depressive symptoms during treatment was independent of major depressive disorder or alcohol diagnoses and predicted treatment attrition. Higher levels of depressive symptoms during treatment were associated with greater urge to use cocaine, alcohol, and other drugs in high-risk situations. Concurrent major depressive disorder and depressive symptoms did not predict cocaine use at follow-up. However, patients who had an alcohol relapse episode experienced more depressive symptoms during treatment than did those who abstained. CONCLUSIONS: The results highlight the relationship of depression to alcohol use among cocaine abusers and suggest a need for further studies of the association between depression and substance use disorders.
Proteus syndrome is a complex hamartomatous disorder characterized by multiple, diverse, somatic manifestations. We present a case in which severe, evolving CNS abnormalities were also exhibited. Imaging findings at presentation included hemimegalencephaly, subependymal calcified nodules, and periventricular cysts. Subsequently, dural sinus thrombosis developed. Eight previously reported patients may also have had hemimegalencephaly. When neuroimaging studies show hemimegalencephaly in a child with pigmented skin lesions, Proteus syndrome should be considered in the differential diagnosis.
Twenty-five patients, 11 to 19 years in age, were treated with hip arthrodesis for an incapacitating painful and stiff hip. Clinical diagnoses included avascular necrosis (AVN) associated with slipped capital femoral epiphysis (SCFE) (7 patients), posttraumatic AVN (6), septic arthritis (4), complication of treatment of developmental dysplasia of the hip (DDH) (4), pathologic fracture of femoral neck through bone cyst with resulting AVN (2), Perthes disease (1), and idiopathic chondrolysis (1). Preoperative motion was minimal or absent in 13 patients, limited in 12, and very painful in 23 patients. A two-incision surgical approach was utilized, providing for an intra-articular fusion technique and internal fixation with precise positioning. The surgical technique described avoids any dissection of the hip abductor musculature or a deforming osteotomy of the proximal femur. Twelve complications occurred in 10 patients, 9 of which required additional operative treatment. At an average postoperative follow-up of 6 years, 10 months, the overall activity level was greatly increased over the preoperative activity level secondary to the relief of pain. Hip arthrodesis is the acceptable salvage procedure for the otherwise healthy, active adolescent or young adult with unilateral hip disease characterized by incapacitating pain and/or an unacceptable fixed position.
An autolysis-resistant mutant of the HIV-I protease was employed for removal of metabolically stabilized and highly bioactive analogues of bovine growth-hormone-releasing factor (bGRF) from their larger either synthetic or recombinant precursors. The N-terminal four amino acids in two selected model GRF analogues, Y1IDAIFTSSYRKVLAQLSARKLLQDILSRQVF32-OH (I; GRF32) and Y1IDAIFTSSYRKVLAQLSARKLLQDILSRQ30-OH (IA; GRF30), conform well to the specificity of the HIV-I protease for residues in the P1' to P4' positions of its peptide substrates. A variety of amino acids were tried in the N-terminal extension (positions P4-P1) to fit the protease substrate specificity for the 8 amino acids in positions P4-P4'. A synthetic precursor of I, extended N-terminally with RQVF-, a sequence representing the four C-terminal residues in I, was effectively cleaved by the protease at the Phe-1-Tyr1 bond (... RQVF-decreases-YIDA ...) to release GRF32. However, when several soluble fusion proteins linked to GRF32 by the RQVF sequence were expressed in Escherichia coli, attempts to cleave out the core GRF32 met with variable, and only limited, success. By random mutagenesis in a propeptide segment, [MGQSVAQVF]-decreases-GRF30, (II) was identified as a construct that showed reasonably high-level expression in E. coli and was effectively processed by the HIV-I protease. A yield of 5 mg of pure GRF30 was obtained/litre of culture medium after a single HPLC purification step.
AIMS: Coping skills training, a promising treatment approach for alcoholics, was adapted for use with cocaine abusers and effects on outcome were investigated. DESIGN: A cocaine-specific coping skills training (CST) package was compared to an attention placebo control when both were added to a comprehensive treatment program. SETTING: The sites were two private substance abuse treatment facilities, one residential and rural, and one an urban partial hospital. PARTICIPANTS: Substance abusers in treatment with cocaine abuse or dependence were selected. INTERVENTION: The CST intervention was conducted in individual sessions. It involved functional analysis of high risk situations and coping skills training based on the functional analysis. FINDINGS: Clients who received CST had significantly fewer cocaine use days and the length of their longest binge was significantly shorter during the 3-month follow-up period compared to clients in the control condition. CST did not affect relapse rates or use of other substances. CONCLUSIONS: Results support the notion that cocaine-specific CST is a promising adjunct to treatment for cocaine abusers.
This study compares philtral development in the normal fetus with philtral development in specimens lacking normal philtral landmarks. Distinct differences in the structure of the upper lip were discovered between the two groups using a histological comparison. A new mechanism for the structural basis of the philtrum is proposed on the basis of these differences.
Formation of CD4-gp160 intracellular complexes represents an important mechanism leading to the induction of receptor interference. Previous studies have demonstrated that cells coexpressing gp160 and CD4 formed complexes of CD4 and gp160 which became blocked within the endoplasmic reticulum (ER), preventing CD4 from reaching the cell surface. In this report we have investigated the domains and residues of CD4 and gp160 involved in intracellular interaction. Accordingly, we have introduced mutations in both CD4 and gp160 at sites previously shown to disrupt CD4-gp120 interactions at the cell surface. Using a T7-vaccinia virus transient expression system, we expressed these gp160 and CD4 mutants in HeLa cells and analyzed their effects on intracellular complex formation and CD4 surface modulation. We observed that a number of gp160 mutants which failed to interact with CD4 at the cell surface also failed to bind and trap CD4 within the ER as expected. However, mutations at a critical residue, W427, did not abrogate intracellular CD4 binding. These gp160 mutants continued to interact with intracellular CD4 and inhibit CD4 transport to the cell surface, although gp120 produced from these mutants did not bind CD4 at the cell surface as expected. A number CD4 mutants also continued to form intracellular complexes with gp160, resulting in the loss of CD4 surface expression. Again, these CD4 mutants did not bind to gp120 at the cell surface, consistent with earlier reports. These results demonstrate that intracellular interactions between gp160 and CD4 in the ER may utilize different contact sites compared to those used during CD4 and gp120 binding at the cell surface. The data provide further evidence that the environment in which CD4 and the HIV-1 envelope glycoprotein interact can have a significant effect on their interaction.
The HIV envelope glycoprotein gp160 plays a major role in the posttranslational down-regulation of its receptor, CD4. In this report we have analyzed the requirements of both CD4 and gp160 involved in transport block of the gp160-CD4 complex causing the down-regulation of cell surface CD4. Using a transient expression system we observed that both soluble and membrane-bound CD4 were equally blocked by the wild-type gp160, indicating that neither the transmembrane domain nor the cytoplasmic tail of CD4 affected its interaction with gp160 or exocytic transport block of the complex. Similarly, deletions of the gp160 cytoplasmic domain or mutation in the transmembrane domain had little effect on its transport, or its ability to down-regulate CD4 surface expression. Furthermore, substitution of the gp160 transmembrane domain and cytoplasmic tail with that of the influenza virus hemagglutinin or with a glycophosphatidylinositol moiety did not affect its ability to bind CD4 and block its transport. However, soluble envelope glycoprotein constructs (either gp120 or soluble gp160) were unable to block CD4 transport to the cell surface despite their binding to CD4 within the ER. Taken together these results demonstrate that neither the gp160 cytoplasmic tail nor the specific sequences of the transmembrane region of gp160 nor the membrane anchoring of CD4 were involved in ER retention of the CD4-gp160 complex and that anchoring of gp160 to the ER membrane was responsible for gp160-mediated cell surface down-regulation of CD4.
The envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) plays a major role in the down-regulation of its receptor, CD4. This down-regulation, at least in part, is caused by the formation of gp160-CD4 intracellular complexes which fail to transport out of the endoplasmic reticulum (ER). In this report, we have evaluated the ability of envelope glycoproteins from various isolates to block CD4 transport within the endoplasmic reticulum. Using a recombinant vaccinia virus expression system in HeLa cells, we expressed different HIV-1 and HIV-2 envelope glycoproteins with CD4. Pulse-chase labeling followed by immunoprecipitation demonstrated that envelope glycoproteins from primary and lab-adapted isolates were capable of forming intracellular complexes with CD4, resulting in the partial inhibition of CD4 transport to the Golgi. Although the efficiency of CD4 modulation was variable, these differences did not correlate with the type of isolate from which the HIV-1 glycoprotein was derived. However, we did find that the HIV-2 ST envelope glycoprotein (gp150) was not as efficient at blocking CD4 as the glycoprotein (gp140) derived from HIV-2 ROD. The decreased ability of ST gp150 to block CD4 within the ER was associated with an increased efficiency of ST gp150 transport and cleavage. Thus, differences in the ability of HIV envelope glycoproteins to block CD4 transport do exist, and these differences may be determined by envelope glycoprotein transport kinetics.
PF4 has previously been shown to have potent inhibitory effects on myoactivity of somatic muscle strips from the nematode. Ascaris suum. This study examined the bioactivity and metabolic stability of position 2- and position 5-modified analogues of PF4. Although the analogues [Leu5]PF4,[Ala2]PF4, [Gly2]PF4, [Ala2,Leu5]PF4, and [Gly2,Leu5]PF4 all had qualitatively similar inhibitory effects on A. suum somatic muscle strips, their effects were quantitatively distinguishable and had the order of potency: PF4 = [Leu5]PF4 > > [Ala2]PF4 = [Ala2,Leu5]PF4 > > [Gly2]PF4 = [Gly2,Leu5]PF4, Leu5 for Ile5 substitutions in PF4 did not alter the activity of this peptide: however, Gly2/Ala2 for Pro2 substitutions reduced, but did not abolish, peptide activity. Peptide stability studies revealed that [Gly2]PF4(2-7) and -(3-7) and [Ala2]PF4(2-7), -(3-7), and -(4-7) fragments were generated following exposure to A. suum somatic muscle strips. However, the parent peptide (PF4) was not metabolized and appeared to be resistant to the sequential cleavages of native aminopeptidases. Observed analogue metabolism appeared to be due to the activity of released aminopeptidases as identical fragments were generated by incubation in medium that had been exposed to somatic muscle strips and from which the strips had been removed prior to peptide addition. It was found that the muscle stretching and bath mixing characteristics of the tension assay led to more effective release of soluble enzymes from muscle strips and thus greater peptide degradation. These studies reveal that Pro2 in PF4 is not essential for the biological activity of this peptide; however, it does render the peptide resistant to the actions of native nematode aminopeptidases.
Awareness of negative consequences of cocaine use is theoretically important for motivation for treatment and relapse prevention. This study reports on the development of an instrument designed to assess cocaine users' self-reported negative consequences of cocaine use. Two samples of cocaine users in treatment for substance abuse completed the Cocaine Negative Consequences Checklist (CNCC). The measure, which is unidimensional in nature with four content area subscales that may be scored, was found to possess excellent reliability across the two samples. The convergent and discriminant validity of the CNCC was supported by the pattern of relationships with other measures of cocaine consequences, cocaine use, the Addiction Severity Index, and with demographic measures. Further research is needed on the utility of this measure in treatment and research.
Assessing outcome is a critical problem for the study of addictive behaviors. Traditional approaches often lack power and sensitivity. Latent Transition Analysis is an alternative procedure that is applicable to categorical latent variable models such as stage models. The method involves four different types of parameters, each of which may be relevant to different research questions. Two examples that employ the Stages of Change construct are used to illustrate the method. In the first example, three different models of longitudinal change are compared. In the second example, the effects of an expert system intervention for smoking is compared to a control condition. The method permits the investigation of a series of specific comparisons: (1) the effectiveness of the intervention for individuals in different stages can be assessed; (2) the effectiveness of the intervention can be evaluated for different time intervals; and (3) the effects of intervention on both progression through the stages and regression through the stages or relapse can be assessed. Other potential applications of the method are also discussed.
A novel FMRFamide-related heptapeptide, Lys-Pro-Asn-Phe-Ile-Arg-Phe-NH2 (KPNFIRFamide), was isolated and characterized from acid ethanol extracts of the free-living nematode, Panagrellus redivivus. Whole-worm extracts contained > or = 9 pmol KPNFIRFamide/g wet weight. A synthetic replicate of this peptide induced a rapid relaxation of tone and inhibited spontaneous contractility in isolated innervated and denervated body-wall muscle strips of the parasitic nematode, Ascaris suum. KPNFIRFamide (0.1 nM) induced measurable relaxations in 50% of the muscle preparations examined. Concentrations > or = 0.3 nM induced relaxation in 100% of muscle preparations examined. The relaxation was short-lived at concentrations of peptide > or = 1 microM and displayed a profile typical of receptor desensitization. These data suggest the occurrence of a closely related peptide in A. suum and add further evidence to the concept of primary structural conservation of FaRPs within the nematodes.