Inhibition of DNA replication factor RPA by p53

The tumour suppressor p53 specifically interferes with the onset of S phase. The mechanism of the growth suppression action of the protein is unclear, though recent evidence points to transcriptional activation and repression functions of the protein. A competing hypothesis suggests that p53 interacts with the DNA replication apparatus and directly interferes with DNA replication. The major evidence for this hypothesis is that p53 interacts with the simian virus 40 (SV40)-encoded protein T antigen and interferes with the ability of T antigen to unwind the SV40 origin of DNA replication, and recruit DNA polymerase alpha to the replication initiation complex. Here we report that p53 physically interacts with and inhibits the function of a cellular DNA replication factor, the single-stranded DNA-binding protein complex RPA.

Do the same stimulus-response relations influence choice reactions initially and after practice?

A two-choice reaction task was used to evaluate changes in stimulus-response translation with practice. In Experiment 1, four groups of Ss practiced with either a direct or indirect mapping of left-right stimuli to left-right responses and either a crossed or uncrossed hand placement and transferred to one of the four Mapping x Placement conditions. Stimulus-response location and response location-effector relations affected performance initially and after practice. In Experiments 2 and 3, Ss switched every 42 trials between conditions for which only the stimulus location-effector (Experiment 2) or stimulus-response location relation (Experiment 3) remained constant. Switching produced interference in Experiment 2 but not in Experiment 3, corroborating the influence of the stimulus-response location relation on performance. Mediation based on spatial codes continues to be a factor in the performance of practiced Ss.

The separability of space and time: dimensional interaction in the memory trace

The speeded-classification paradigm, adapted from the study of perceptual interactions, was used to examine interactions among features of the short-term memory trace. In each of four experiments, a trial began with the presentation of a pair of stimuli, each member of which occurred either first or second in time and above or below a fixation point. One of the two stimuli was then presented again, and the task was to classify its prior temporal (Experiments 1 and 3) or spatial (Experiments 2 and 4) position. The main question of interest asked whether subjects could selectively attend to one of these occurrence dimensions while ignoring irrelevant variation along the other. The results suggested that whereas subjects can selectively ignore temporal or spatial variation when no recall of the irrelevant dimensions value is required, they suffer interference when values on both dimensions must be remembered. The obtained patterns of interference are consistent with postperceptual interactions of the spatial and temporal components of the memory trace.

Do the same stimulus-response relations influence choice reactions initially and after practice?

A two-choice reaction task was used to evaluate changes in stimulus-response translation with practice. In Experiment 1, four groups of Ss practiced with either a direct or indirect mapping of left-right stimuli to left-right responses and either a crossed or uncrossed hand placement and transferred to one of the four Mapping x Placement conditions. Stimulus-response location and response location-effector relations affected performance initially and after practice. In Experiments 2 and 3, Ss switched every 42 trials between conditions for which only the stimulus location-effector (Experiment 2) or stimulus-response location relation (Experiment 3) remained constant. Switching produced interference in Experiment 2 but not in Experiment 3, corroborating the influence of the stimulus-response location relation on performance. Mediation based on spatial codes continues to be a factor in the performance of practiced Ss.

Initial intensive therapy for multibacillary leprosy patients--in retrospect

We analysed the results of 4845 multibacillary (MB) patients being treated with multidrug treatment (MDT) in the Srikakulam District of Andhra Pradesh, India. Of these, 2309 (47.7%) patients were given an initial 14-day intensive therapy with rifampicin, clofazimine and dapsone, followed by the WHO recommended pulse therapy. The rest of the cases were given only pulse therapy. The improvement in terms of bacteriological clearance and the proportion of cases declared released from treatment (RFT) was found to be significantly higher among patients treated with only pulse therapy. Clinic attendance was found to be better and more regular in patients treated with intensive therapy, and no relapses were seen with either therapy. The implications of these findings on the operational aspects of programme implementation are discussed.

Influence of Composition and Processing History on the Cellular Morphology of the Foamed Olefinic Thermoplastic Elastomers

Foam extrusion of a series of dynamically vulcanized polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) blends (commercially available Santoprene) by using chemical blowing agents have been studied. Results suggest that foaming occurs only within the thermoplastic phase and for each composition there exists a limiting density which controls the maximum volume expansion. This limiting density is controlled only by the composition and is independent of the blowing agent concentration, extrusion conditions, and the geometry. For the softest and the hardest blends, maximum volume expansion was found to be about 20 and 100%, respectively. Considerable differences in cell structure were also observed with change in the blend composition. As the rubber content increases, bubbles change their shapes from spherical to highly elongated channels where long axes are primarily along the extrusion direction. When the shapes of the bubbles are viewed by cutting the specimen, the bubbles were found to become highly irregular as the rubber content was increased. The fractal dimension of the perimeter profiles revealed that increases in rubber content give increases in the characteristic fractal dimension. Additionally, wide angle x-ray pole figure analysis, which gives an average orientation behavior of the material, indicates that low levels of preferential crystalline chain orientation develop in the extradates. This preferential orientation was found to vary from skin to core.

Foaming of Vulcanized PP/EPDM Blends Using Chemical Blowing Agents

Using two different chemical blowing agents, foaming behavior of partially vulcanized PP/EPDM blends with high EPDM ratio has been studied. The objective was to induce foaming within the EPDM phase prior to complete curing. The results suggest that with proper choice of blowing agent and by optimum balance of curative loading, foams with densities as low as 0.55 g/cm3 could be obtained. This corresponds to nearly 90 percent density reduction which is significantly greater than the 15 to 20% afforded by similar fully-vulcanized dynamically cured blends reported previously. The degree of cure in the rubber phase was determined to play a key role in determining the overall foamability. In particular, the foamability of the blend was found to decrease linearly with increase in the gel content. In addition, the compounding technique also plays a major role in controlling foamability of these blends. Attempts at extrusion foaming of these blends, however, were successful only for blends with a rather low degree of cure.

Persistence of stimulus-response compatibility effects with extended practice

The influence of extended practice on stimulus-response (S-R) compatibility effects was investigated. Three experiments, each extending over a period of 8 sessions, were conducted. The nature and degree of compatibility was manipulated across experiments. In all experiments, a persistent effect of S-R compatibility on reaction times was observed. Thus, the lower bound for reaction times appears to be less for compatible assignments than for incompatible assignments. This persistence of S-R compatibility indicates that the initial codings used to perform a novel task continue to exert an influence on later performance.

cdc2 family kinases phosphorylate a human cell DNA replication factor, RPA, and activate DNA replication

RPA is a single-stranded DNA binding protein complex purified from human cells and is essential for the initiation and elongation stages of SV40 DNA replication in vitro. In both human and yeast cells, the 34 kDa polypeptide subunit of RPA is phosphorylated in the S and G2 phases of the cell cycle and not in G1. One of the major RPA kinases present in extracts of human cells was purified and shown to be the cyclin B-cdc2 complex. This purified kinase, and a closely related cyclin A associated cdc2-like kinase, phosphorylated RPA p34 on a subset of the chymotryptic peptides that were phosphorylated in vivo at the G1-S transition. Two serines near the N-terminus of RPA p34 were identified as possible sites of phosphorylation by cdc2 kinase. These same serines were necessary for RPA phosphorylation in vivo. The purified cdc2 kinase stimulated SV40 DNA replication in vitro when added to G1 cell extracts. The kinase also stimulated unwinding at the origin of replication, one of the earliest steps in DNA replication requiring RPA, but only in the presence of an additional factor present in G1 cell extracts. Thus, one or more members of the cyclin-cdc2 kinase family may be required for the initiation and maintenance of S phase, in part due to their ability to phosphorylate and activate a cellular DNA replication factor, RPA.

Numerical analysis of flow in an elastic artery model

Oscillatory and pulsatile flows of Newtonian fluids in straight elastic tubes are simulated numerically with the aid of Ling and Atabek's "local flow" assumption for the nonlinear convective acceleration terms. For the first time, a theoretical assessment of the local flow assumption is presented, and the range of validity of the assumption is estimated by comparison with perturbation solutions of the complete flow problem. Subsequent simulations with the local flow model indicate that the flow field and associated wall shear stress are extremely sensitive to the phase angle between oscillatory pressure and flow waves (impedance phase angle). This phase angle, which is a measure of the wave reflection present in the system, is known to be altered by arterial disease (e.g., hypertension) and vasoactive drugs. Thus, the paper elucidates a mechanism by which subtle changes in systemic hemodynamics (i.e., phase angles) can markedly influence local wall shear stress values.

Persistence of stimulus-response compatibility effects with extended practice

The influence of extended practice on stimulus-response (S-R) compatibility effects was investigated. Three experiments, each extending over a period of 8 sessions, were conducted. The nature and degree of compatibility was manipulated across experiments. In all experiments, a persistent effect of S-R compatibility on reaction times was observed. Thus, the lower bound for reaction times appears to be less for compatible assignments than for incompatible assignments. This persistence of S-R compatibility indicates that the initial codings used to perform a novel task continue to exert an influence on later performance.

Single-dose pharmacokinetics of piperacillin and tazobactam in patients with renal disease

Tazobactam is an irreversible inhibitor of many beta-lactamases. In combination with piperacillin, tazobactam exhibits synergy against many beta-lactamase-producing bacteria. The pharmacokinetics of piperacillin and tazobactam were evaluated in eight normal volunteers and in 52 patients with renal dysfunction. Plasma and urine were obtained for up to 30 hours after an infusion of piperacillin and tazobactam (3 and 0.375 gm, respectively). Dialysate samples were collected from patients undergoing dialysis. Piperacillin and tazobactam concentrations were determined by high-performance liquid chromatography. Noncompartmental methods were used for pharmacokinetic analysis. Piperacillin and tazobactam total body clearance, area under the curve, and terminal elimination rate correlated with renal function. Hemodialysis removed 31% and 39% of piperacillin and tazobactam, respectively. During continuous ambulatory peritoneal dialysis, 5.5% of the piperacillin and 10.7% of the tazobactam was recovered in the dialysate over 28 hours. Peak plasma concentrations of both drugs increased minimally with decreasing creatinine clearance. Dosage alterations for creatinine clearance values less than 40 ml/min are recommended.

Is bacteriological examination by skin smear necessary in all paucibacillary leprosy patients in mass control programmes?

Skin smear bacteriological examination results of 11,255 paucibacillary leprosy patients from 8 leprosy control units under the National Leprosy Eradication Programme (NLEP) in South India and the Outpatient Department (OPD) of the Central Leprosy Teaching & Research Institute (CLT&RI), Chengalpattu, between 1987 and 1989 were collected and analysed. Only 0.05% of the smears from leprosy control units and 2.49% from the OPD of CLT&RI were found to be positive. Not a single smear from indeterminate, tuberculoid and pure neuritic types of leprosy out of 8263 examined was found positive under field conditions. The relevance of carrying out routine bacteriological examination in mass leprosy control programmes is discussed.

Seroepidemiological study of leprosy in a highly endemic population of south India based on an ELISA using synthetic PGL-I

As part of a continuing longitudinal immuno-epidemiological study, blood samples were collected by finger prick from 4243 individuals living in a highly endemic area for leprosy in South India. The samples were tested for IgM antibodies against phenolic glycolipid-I using an ELISA. Seropositivity defined as optical density greater than or equal to 0.2000 was marginally higher in the age group 10-30 years and in females. There was no evidence for a higher level in contacts than in non-contacts. The future prospect for the large scale use of this ELISA in high-endemic populations in special epidemiological investigations or routine control programs as a serological tool to detect leprosy infection appears questionable.

Audit in two acute psychiatric units

The Royal College of Psychiatrists (1989) has recently produced its own preliminary report on medical audit. It defines medical audit as: “The systematic, critical analysis of the quality of medical care, including the procedures used for diagnosis and treatment, the use of resources and the resulting outcome and quality of life for the patients.” This definition is in essence similar to that of the Royal College of Physicians.

Who commits patricide?

The authors studied 10 men charged with patricide, including 2 men charged with both patricide and matricide and compared them with 10 schizophrenic patients who did not commit any crime. Eight patients who committed patricide were diagnosed as suffering from schizophrenic illness and 2 patients received a diagnosis of personality-disorder. Seven schizophrenics who committed patricide and both personality-disordered patients had a cruel and unusual relationship with their father. All were single at the time of patricide. The EMBU inventory revealed fathers to be more punitive than mothers and fathers favoured siblings more than the patients. Mothers were more overprotective and tolerant than fathers. Patricide patients' fathers were more punitive and shaming than control patients' fathers, and control patients' fathers were more stimulating and depriving than patricide patients' fathers. Patricide patients' mothers were more overinvolved and tolerant than control patients' mothers. A sense of relief was felt following the patricide rather than remorse. In contrast, the majority of patients in the control group described their father and mother as kind and affectionate. The EMBU inventory did not reveal any significant difference between father and mother.

Double-blind, randomized, controlled clinical trial of norfloxacin for cholera

In a double-blind, randomized clinical trial with 78 adults with acute watery diarrhea and severe dehydration, 37 subjects were positive for Vibrio cholerae. In conjunction with rehydration therapy, 13 patients received norfloxacin, 12 received trimethoprim-sulfamethoxazole (TMP-SMX), and 12 received a placebo. Norfloxacin was superior to TMP-SMX and to the placebo in reducing stool output, duration of diarrhea, fluid requirements, and vibrio excretion. TMP-SMX was no better than the placebo.

Serum and v-src increase the level of a CCAAT-binding factor required for transcription from a retroviral long terminal repeat

Transcription from the long terminal repeat (LTR) of Rous sarcoma virus (RSV) in rat 3Y1 fibroblasts was dependent on the presence of serum. Within 1 hr after addition of serum to a serum-deprived culture, there was a fivefold increase in the level of transcripts initiated at the LTR. This stimulation did not require synthesis of new proteins. The induction of transcription by serum was mostly dependent on two CCAAT boxes in the LTR. Within 1 hr after addition of serum, there was also an increase in the level of a nuclear protein that bound to the two CCAAT boxes, even in the presence of cycloheximide. This serum-induced CCAAT factor also bound CCAAT sequences from other promoters, for example, those of human heat shock protein 70, human c-Ha-ras, and human histone 1, but not to the adenovirus origin of replication or the SV40 enhancer core sequence, suggesting that it was related to CP1 or CP2. Expression from the RSV LTR was not dependent on serum in v-src-transformed cells. Using temperature-sensitive v-src, it was shown that the tyrosine kinase activity of the oncogene increased the amount of CCAAT factor that was present in the nucleus. These findings demonstrate that a basal transcription factor, the CCAAT-binding factor, could be a second messenger for transducing a primary signal from serum to the cellular transcriptional apparatus. This also suggests a pathway by which a tyrosine kinase oncogene could influence the transcription of several genes in the nucleus.

Serum independence of transcription from the promoter of an avian retrovirus in v-src-transformed cells is a primary, intracellular effect of increased tyrosine phosphorylation

We found that transcription from the promoter in the long terminal repeat of Rous sarcoma virus in rat 3Y1 cells is dependent on the presence of serum in the culture. However, this serum dependence of transcription was relieved when 3Y1 cells were transformed by the oncogene v-src. Crossfeeding experiments showed no evidence for the production of a serum-substituting extracellular growth factor by the transformed cells. Using 3Y1 cells transformed with temperature-sensitive Rous sarcoma virus, we showed that the tyrosine kinase activity of pp60v-src was responsible for the serum-sparing effect on the level of RNA expressed from the viral promoter. Sodium orthovanadate, an inhibitor of phosphotyrosine phosphatases that nonspecifically elevates the level of phosphotyrosine-containing proteins in cells, stimulated transcription from the viral promoter. The effects of both pp60v-src and orthovanadate were resistant to cycloheximide. These results suggest that the serum independence of transcription from the viral promoter in v-src-transformed cells was probably due to the constitutive activation of intracellular growth-factor pathways by the tyrosine kinase activity of pp60v-src.

Pargyline-sensitive selective accumulation of a radiolabeled MPTP analog in the primate cerebral cortex and basal ganglia

The distribution of radioiodinated N-methyl-4-(4-hydroxy-3-iodobenzyl)-1,2,3,6-tetrahydropyridine (MHTP), an analog of the reportedly nontoxic N-methyl-4-benzyl-1,2,3,6-tetrahydropyridine, (4-homo-MPTP), has been studied in the primate. [123I]MHTP-derived radioactivity exhibited a progressive accumulation and prolonged retention within the primate eye. Following iv injection, [123I]MHTP rapidly accumulated within the primate brain and was subsequently oxidized to a radiolabeled metabolite. The half-life of [123I]MHTP-derived radioactivity within the primate brain was 50 min. The highest concentrations of radioactivity were found in the caudate-putamen and the frontal, temporal and cingulate cortices; the substantia nigra and inferior olivary nucleus were labeled with medium intensity. Very low concentrations of radiolabel were detected in the cerebellum and white matter. Selective accumulation of [125I]MHTP-derived radioactivity within these structures was blocked by pretreatment with pargyline, suggesting that monoamine oxidase B is involved in the bioactivation of radioiodinated MHTP.

Numerical simulation of sinusoidal flow in a straight elastic tube: effects of phase angles

Numerical simulations of flow in straight elastic (moving wall) tubes subjected to a sinusoidal pressure gradient were performed for conditions prevailing in large and medium sized arteries. The effects of varying the phase angle between the pressure gradient and the tube radius, the amplitude of wall motion, and the unsteadiness parameter (alpha) on flow rate and wall shear stress were investigated. Mean and peak flow rates and shear stresses were found to be strongly affected by the phase angle between the pressure gradient and the tube radius with greater sensitivity at higher diameter variation and higher alpha. In large artery simulations (alpha = 12), means flow rate was found to be 60% higher and peak flow rate to be 73% higher than corresponding rigid tube values for certain phase angles, while a threefold increase in mean wall shear stress and sevenfold increase in peak wall shear stress were observed in a sensitive phase angle range. Significant reversal in the wall shear stress direction occurred in the sensitive phase angle range even when there was negligible flow rate reversal. All effects were greatly diminished in simulations of medium sized vessels (alpha = 4). Some experimental evidence to support the predictions of a strong effect of phase angle on wall shear stress in large vessels is presented. Finally, physiological implications of the present work are discussed from a basis of aortic input impedance data, and a physical explanation for the extreme sensitivity of the flow field to small amplitude wall motion at high alpha is given.

Intrapelvic obturator neurectomy in cerebral palsy

Results of 202 obturator neurectomies including 190 intrapelvic and 8 extrapelvic obturator neurectomies in 100 patients were evaluated. Obturator neurectomy, intrapelvic in particular, yielded gratifying results in properly selected patients. It controlled adductor spasticity, scissoring, improved perineal care and helped the patients in sitting and early ambulation. Pre- and post-operative intensive physiotherapy was necessary to get maximum benefit of the surgery. Poor motor status, low IQ, athetosis and inadequate post-operative care had adverse effect on final outcome.

Increased dolichol content in glucocorticoid-sensitive human T-cell leukemia line grown in the presence of dexamethasone

Two cell lines, derived from human T-cell acute leukemia, one glucocorticoid sensitive (CEM-C7) and the other glucocorticoid resistant (CEM-C1) were grown in the presence of 1 x 10-7 M dexamethasone and were analyzed for their dolichol content. After 24 hrs of incubation, dolichols became significantly elevated in the sensitive but not in the resistant line. Lovastatin, the specific inhibitor of cholesterol synthesis did not affect dolichol levels in either of the two cell lines. The results raise the possibility that dolichol accumulation might be involved in the early stages of the glucocorticoid-induced apoptosis (directed cell killing).

The putative trans-activator in the MAgag region of Rous sarcoma virus is not required for cell transformation

A stop codon created by oligonucleotide-directed mutagenesis in the proposed transcriptional trans-activator of Rous sarcoma virus (S. Broome and W. Gilbert, Cell 40:537-546, 1985) which truncated the trans-activator by half did not alter the transforming activity or the replication of the virus in primary chicken embryo fibroblasts. This result proves that this trans-activator is not essential for transformation of primary cells by Rous sarcoma virus.

Phosphorylation of serum response factor, a factor that binds to the serum response element of the c-FOS enhancer

Serum and growth factor regulation of c-FOS protooncogene transcription is mediated by the serum response element. A factor, serum response factor, binding to this element has already been identified. We demonstrate that serum response factor is phosphorylated in vivo on serine residues and that phosphatase treatment of this factor in vitro abolishes its DNA-binding activity. These results show phosphorylation of serum response factor to be required for its DNA-binding activity. The importance of serum response factor phosphorylation for the regulation of c-FOS expression is discussed.

Studies of potential filaricides: Part 14--Activity of 1-iso-butoxycarbonyl-4-methylpiperazine against experimental filariasis

The synthesis and filaricidal activity of 1-iso-butoxycarbonyl-4-methylpiperazine against Litomosoides carinii in Sigmodon hispidus and Dipetalonema viteae in Mastomys natalensis is reported. At an intraperitoneal or oral dose of 3 mg/kg given for 6 days, the compound removed 91% of the circulating microfilariae but had no effect on adult L. carinii. However, it killed all microfilariae and adults of D. viteae at a subcutaneous dose of 50 mg/kg given for 6 days. The compound also possessed chemoprophylactic activity against the larvae of L. carinii and D. viteae at a dose of 30 and 50 mg/kg respectively.

Studies on the effects of low doses of 5 alpha-dihydrotestosterone (DHT) on the basal levels of serum gonadotropins and the sensitivity of the pituitary to luteinizing hormone releasing hormone (LHRH) in adult male rats

Investigations were undertaken to study the effect of administering s.c. 10, 25, 50, 100, 500 and 1000 ng DHT/rat/day to normal adult male rats, for six weeks, on the basal levels of serum gonadotropin and the sensitivity of the pituitary to LHRH. The control group received olive oil. Animals were weighed and bled via cardiac puncture before the beginning of the treatment and weekly thereafter. After the last bleeding rats were injected intracardially 200 ng LHRH/rat and killed 15 min later. Blood, pituitary and testes were collected. Data were analyzed with respect to the control group and with respect to day zero of the treatment. DHT failed to produce a persistent effect on the serum gonadotropin. 10 and 500 ng DHT suppressed FSH levels significantly on days 21 and 7, respectively. 25, 50, 100 and 1000 ng DHT stimulated the release of FSH on day 42. 10 ng DHT reduced the levels of LH on day 14 of the treatment. 10, 25 and 50 ng DHT increased the sensitivity of the pituitary to release more LH in response to LHRH while 100, 500, 1000 ng DHT inhibited LHRH induced release of FSH. DHT at all doses tested failed to affect intrapituitary levels of LH and FSH. 10, 500 and 1000 ng DHT reduced the weights of the pituitaries as compared to the control group. The data demonstrate effects of DHT which are transient on the basal release of gonadotropins but are more persistent and differential on the sensitivity of the pituitary to LHRH.

Studies on the partial structure of the O-antigen of Vibrio cholera Ogawa G-2102

Detailed information was obtained regarding the partial structure of the lipopolysaccharide (LPS), containing glucose, glucuronic acid, 2-amino-2-deoxy-glucose, L-glycero-D-gluco-heptose, and small proportions of L-glycero-D-manno-heptose, mannose, and galactose, isolated from Vibrio cholera Ogawa G-2102. Structures of three oligosaccharides were determined. Results of deamination experiments established the sequence of the linkages between the amino sugar and heptose residues in the O-antigenic polysaccharide.