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Biomedical subjects

R W Smith

Publications and source records attributed to R W Smith.

At least 55 records · Page 3Linked to original sources
PubMed1997

Early postoperative feeding after elective colorectal surgery.

BACKGROUND: Several investigators have demonstrated that routine nasogastric decompression after abdominal surgery is unnecessary and can be safely eliminated, and 1 recent study demonstrated the safety of early oral feedings. OBJECTIVE: To test the hypothesis that successful early feeding would lead to a shorter duration of hospitalization and, therefore, would be more cost-effective. PATIENTS: Fifty-eight patients with elective colorectal surgery. METHODS: Patients were prospectively randomized to 1 of 2 postoperative treatment arms: early feeding (EF group, n = 29) and traditional feeding (TF group, n = 29). All patients in the EF group began a liquid diet on the first postoperative day and were advanced to a regular diet when they consumed 1000 mL in 24 hours. All patients in the TF group began a liquid diet after resolution of the postoperative ileus and were advanced to a regular diet after consuming 1000 mL in 24 hours. Patients were dismissed after tolerating two thirds of the regular diet. Both groups had intraoperative orogastric tubes that were removed at the end of surgery. Nasogastric tubes were inserted for persistent postoperative vomiting. RESULTS: No significant differences were noted in age, types of procedures, or in prior abdominal surgery in either group. No significant differences were seen in rates of nausea (55% in EF vs 50% in TF group) or vomiting (48% in EF vs 33% in TF group). One patient in the EF group had aspiration pneumonia, and anastomotic leak resulted in sepsis and eventual death of 1 patient in the TF group. No significant difference was observed in length of hospital stay between the 2 groups (mean +/- SD, 7.2 +/- 3.3 days in EF vs 8.1 +/- 2.3 days in TF group). CONCLUSIONS: Early oral feeding after elective colorectal surgery is safe. Most of the patients tolerated EF; however, there was no significant difference in duration of hospitalization in these patients.

Adult↗
PubMed1997

Cold intolerance following peripheral nerve injury. Natural history and factors predicting severity of symptoms.

Cold intolerance can be severe and debilitating following injury to the hand. Little is known about its natural history and factors predicting symptom severity. We looked retrospectively at upper limb peripheral nerve injuries over a 12-year period. Information was obtained using a patient questionnaire and patient records. The incidence of cold intolerance was 83%. In 48% the onset of symptoms was within 1 month of the initial injury. At a mean follow-up of 51 months improved symptoms were reported by 21%, while 18% deteriorated. Patients were more likely to develop cold intolerance if they smoked and less likely if they suffered a sharp injury. A score defining the severity of cold induced symptoms, based on the information collected, was calculated for each patient. Significantly increased severity was associated with complete nerve division, median and ulnar nerve division and an associated vessel injury. Symptom improvement was significantly more likely in non-smokers and a deterioration most likely with a high severity score.

Adolescent↗
PubMed1997

Autoregulation of the Escherichia coli replication initiator protein, DnaA, is indirect.

The expression of dnaA is autoregulated, in that transcription of the gene increases when DnaA is inactivated (and initiation of replication prevented) and decreases when DnaA is supplied in excess. However, the inactivation of DnaA does not necessarily lead to increased DnaA production, as dnaA(Ts; temperature sensitive) strains which are integratively suppressed by derivatives of the plasmid R1 do not show temperature-induced derepression. Several possible explanations for this unanticipated behaviour were considered and ruled out. We suggest here that the completion of a critical step in initiation may prevent dnaA derepression: although DnaA would be required to complete this step at oriC, DnaA(Ts) would be sufficient at the R1 origin. Autoregulation of dnaA has been attributed to the binding of DnaA at a consensus binding site in the dnaA promoter region. We show here, using reporter systems, that this DnaA-binding site is not required for the autoregulatory response. We find, further, that replacement of the chromosomal dnaA gene with one containing a mutated binding site causes no demonstrable phenotypic change: cells with the mutant gene show no disadvantage in competition with dnaA+ cells.

Bacterial Proteins↗
PubMed1997

Chrysiasis.

Explore the source record for details and available documents.

Antirheumatic Agents↗
PubMed1997

A cell-free replication system for human polyomavirus JC DNA.

The human polyomavirus JC virus (JCV) establishes persistent infections in most individuals and is the etiologic agent of progressive multifocal leukoencephalopathy. In this report, we describe the establishment of a soluble cell-free system that is capable of replicating exogenous plasmid DNA containing the JCV origin of replication. Replication in this system is completely dependent on the addition of JCV large T antigen (TAg). To prepare JCV TAg for replication analysis, a recombinant baculovirus containing the JCV TAg-coding sequence was generated. TAg expressed in insect cells was purified by metal chelate chromatography. JCV TAg supported initiation of JCV DNA replication in the presence of DNA polymerase alpha-primase, replication protein A, and topoisomerase I in a dose-dependent manner and was also capable of supporting DNA replication in crude human cell extracts. Point mutation of TAg-binding site I strongly diminished TAg binding and concomitantly reduced JCV DNA replication in vivo and in vitro by approximately 50%. Point mutation of TAg-binding site II or deletion of the early palindrome completely abolished replication of JCV origin-containing plasmid DNA in vivo and in vitro, marking these sequences as essential components of the JCV core origin. A comparison of several TAgs showed that simian virus 40 TAg, but not mouse polyomavirus (PyV) TAg, supported replication of a plasmid containing a JCV origin. These findings provide evidence that replication in the cell-free system faithfully mimics JCV DNA replication in vivo. Therefore, it may be a useful tool for future analysis of interactions between JCV and its host cell.

Animals↗
PubMed1996

N-aryl-3,3,3-trifluoro-2-hydroxy-2-methylpropanamides: KATP potassium channel openers. Modifications on the western region.

A subset of antiandrogen compounds, the N-aryl-3,3,3-trifluoro-2-hydroxy-2-methylpropanamides 1, were found to activate ATP sensitive potassium channels (KATP) and represent a new class of potassium channel openers (PCOs). A structure-activity relationship was carried out on the western region of this series with the goal of obtaining an activator of the ATP sensitive potassium channel suitable for use in the treatment of urge urinary incontinence. In particular three large 4-(N-aryl) substituents, the (N-phenyl-N-methylamino)sulfonyl, benzoyl, and 4-pyridylsulfonyl moieties, yielded non-antiandrogen, KATP potassium channel openers (39, 41, and 64, respectively) that are bladder selective in an in vivo rat model that simultaneously measures bladder contractions, heart rate, and blood pressure. Substitutions of the aryl rings of 41 and 64 gave several derivatives that also display selectivity in the in vivo rat model; however, none appear to offer a substantial advantage over 41 and 64. The PCO activity of 41 and 64 resides in the (S)-(-) enantiomers. ZD6169, 41(S), has been selected into development for the treatment of urge urinary incontinence.

Amides↗
PubMed1996

Open versus stereotactic breast biopsy.

BACKGROUND: Stereotactic breast biopsy has been developed as a less invasive means of performing biopsy for mammographic abnormalities. METHODS: From July 1994 through June 1995, 103 women with mammographic abnormalities requiring biopsy were prospectively evaluated. RESULTS: Fifty-one women had open biopsy, and 52 women had stereotactic biopsy. The average age in both groups was 60 years. Pathology revealed malignancy in 12% of stereotactic biopsies and 13% of open biopsies. Complications occurred in 6% of the open biopsies and 4% of the stereotactic biopsies and were limited to hematomas or seromas. The average cost was $2400 for open biopsy and $650 for stereotactic biopsy (P < 0.01). One hundred and one patients returned for a follow-up mammogram within 6 months, and 1 patient in each group required a second biopsy, which revealed benign pathology. A Patient Satisfaction Survey revealed no significant differences in patient satisfaction between the two types of procedures. CONCLUSION: There were no differences between open and stereotactic biopsies in regards to diagnostic accuracy, complications, or patient satisfaction. A significant difference was noted in charges during the time frame of our study.

Biopsy, Needle↗
PubMed1996

Sudden insight: all-or-none processing revealed by speed-accuracy decomposition.

Issues surrounding the discreteness or continuity of cognitive processes have played a major role in experimental psychology, although there has been relatively little work that directly addresses these topics. Nevertheless, there has been a shift away from discrete models and toward continuous ones. The research reported in this article demonstrates discrete processing of information in an anagram task selected because of its similarity to insight problems, which seem subjectively to produce discrete "illumination" during processing. The authors used speed-accuracy decomposition (SAD), a relatively new technique for investigating the time course of information processing. The results of 2 experiments indicate little or no partial information in the anagram tasks, in contrast to previous research with SAD, all of which has revealed partial information. General models of human information processing must therefore be able to account for both patterns.

Cognition↗
PubMed1996

The coupling between ftsZ transcription and initiation of DNA replication is not mediated by the DnaA-boxes upstream of ftsZ or by DnaA.

The DnaA protein of Escherichia coli is a multi-functional protein which, In addition to promoting initiation of replication, can regulate the initiation or termination of transcription of a variety of genes. It acts by binding to DNA at a defined sequence, termed a DnaA-box. Three candidate DnaA-boxes which occur within the essential cell-division genes, ftsQ and ftsA, have been hypothesized to mediate the response of the downstream ftsZ gene to intracellular levels of DnaA, and thus to couple the processes of initiation and cell division. We show here that, although transcription from promoters upstream of ftsZ is increased when initiation of chromosome replication is blocked by DnaA inactivation, this response is not mediated by the DnaA-boxes near these promoters, nor is it specific to DnaA. We show, furthermore, that mutational inactivation of the putative DnaA-binding sites in the fts region of the chromosome does not lead to impaired growth or reduced survival of cells.

Bacterial Proteins↗
PubMed1996

Tissue-specific changes in protein synthesis rates in vivo during anoxia in crucian carp.

Mechanisms of anoxia tolerance were investigated in crucian carp. Rates of protein synthesis were calculated in selected tissues of normoxic and anoxic animals. Exposure to 48 h of anoxia resulted in a significant reduction in protein synthesis in the liver (> 95%), heart (53%), and red and white muscle (52 and 56%, respectively), whereas brain protein synthesis rates were unaffected. Seven days of anoxia produced similar results. After 24 h of recovery from a 48-h anoxic period, protein synthesis rates had virtually returned to normoxic values. The effect of anoxia on the amount of RNA (relative to protein) varied depending on the tissue and also the length of exposure (except in the brain, where it was consistently reduced). However, the effect on RNA translational efficiency was purely tissue specific (i.e., independent of exposure time) and was unaffected in the heart, reduced in the liver and red and white muscle, and increased in the brain. Downregulation of protein synthesis on a tissue-specific basis appears to be a significant mechanism for energy conservation as well as maintaining neural function, thus promoting survival during anoxia.

Animals↗
PubMed1996

Trochanteric bone grafts in foot and ankle surgery.

Eighty-five patients who underwent trochanteric bone graft harvest in association with foot and ankle surgery were studied retrospectively by patient questionnaire. The average follow-up was 49 months (range, 14-101 months). Ninety-five percent of the patients expressed satisfaction with the procedure, in that they would choose to accept the trochanteric bone graft again if required to make the choice. However, 31% of the patients acknowledged some degree of hip discomfort and 4% reported some daily pain. Nineteen of 85 patients (22%) were treated for trochanteric pain. Most patients responded to strengthening/stretching and heat/ice. Four patients (5%) had failed or delayed union of the arthrodesis in which trochanteric bone graft was utilized. The greater trochanter may be considered as an alternative for major bone graft when the iliac bone is not available and when weightbearing is restricted for at least 6 weeks after surgery. As with the use of iliac bone graft, patients should be alerted to the possibility of postoperative discomfort. Surgical details should be followed to minimize the risk of peritrochanteric fracture.

Adolescent↗
PubMed1996

Quantitative analysis of cancellous bone graft available from the greater trochanter.

To quantify the amount of cancellous bone graft available from the greater trochanteric region, 20 paired iliac crest-proximal femur specimens were harvested and compared in 10 adult pelvises. A 1.3 x 1.3-cm cortical window was made in the lateral aspect of the proximal femur 2 cm distal from the tip of the greater trochanter. Cancellous bone evacuation was performed by curettage. The extent of harvest was mechanically limited by the medial wall of the trochanter and by curette impingement on the margins of the cortical window. The graft was quantitated after maximal digital compression in a 10-ml syringe and compared with cancellous graft obtained from the paired anterior iliac crest. The average compressed volume of cancellous bone harvested from the greater trochanter was 6.5 ml (range, 4.2-9.6 ml). The average iliac crest cancellous bone volume was 6.0 ml (range, 2.7-8.8 ml). Differences in graft volume between the anterior iliac crest and the trochanter were not statistically significant. The resulting defect in the proximal femur remained isolated to the trochanteric region. In this study, we demonstrate that cancellous bone is available from the greater trochanteric region in an amount similar to that available from the anterior iliac crest. We also show that it is obtainable in a reproducible manner. Our clinical experience of over 100 cases has demonstrated acceptable morbidity associated with this technique. The greater trochanteric region may be used as a secondary source of autogenous cancellous bone graft when specific procedures demand more bone graft than available from the iliac crest alone, or in patients who have had previous iliac crest graft harvest.

Adult↗
PubMed1996

Vasculitis masquerading as neurologic decompression illness.

An adult male diver developed limb pains and peripheral neurologic signs following a series of dives. He was treated for acute neurologic decompression illness (DCI) and responded well, but subsequently he deteriorated and developed features of a progressive multisystem disease. Investigation confirmed a clinical diagnosis of polyarteritis nodosa complicated by a mononeuritis multiplex. Vasculitis is uncommon and its masquerade as neurologic DCI may be unique. However, this case empha-sizes the importance of careful clinical assessment and illustrates the potentially wide differential diagnosis of DCI.

Adult↗
PubMed1995

Speed-accuracy decomposition yields a sudden insight into all-or-none information processing.

The existence of discrete all-or-none information processing has often been assumed as a basis for stage models and also as an important characteristic of nonlinear connectionist models; however, there has been little or no hard empirical evidence supporting the existence of this phenomenon. In search of such evidence, we applied speed-accuracy decomposition (Meyer et al., 1988), a technique for detecting partial response information, to the examination of the time-course of processing in a (Gestalt) insight-like task, namely, anagram solution. This task was chosen because the Gestalt psychologists conjectured that insight is a sudden, discrete phenomenon. Supporting this view, we found little or no evidence of partial information in two experiments, thereby providing what may be the strongest evidence to date for all-or-none processing.

Adult↗
PubMed1995

Clearing the cervical spine in obtunded patients: the use of dynamic fluoroscopy.

OBJECTIVE: Obtunded patients (Glasgow Coma Scale score of < 13) with normal cervical roentgenograms remain in collars until they can be clinically evaluated. Cervical collars provide incomplete immobilization and have complications. Our hypothesis was that cervical spines could be evaluated in obtunded patients with normal cervical roentgenograms using dynamic fluoroscopy. DESIGN: This study was a prospective clinical evaluation. METHODS: Obtunded trauma patients with normal cervical roentgenograms underwent fluoroscopic examination of the cervical spine through a full range of motion. RESULTS: Fluoroscopic evaluations were done in 116 patients. There were 113 true negative examinations. Two patients had facet fractures not diagnosed on cervical roentgenograms, and no instability on fluoroscopy. One patient had a positive exam, with 2 mm of subluxation. There were no neurologic complications. Decubiti were present in 44% and were more frequent when the collar was on > 5 days (p = 0.029). CONCLUSIONS: Dynamic fluoroscopy can safely and effectively clear the cervical spine in obtunded patients. Earlier removal of the collar decreases decubiti.

Adult↗