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Biomedical subjects

C Smith

Publications and source records attributed to C Smith.

At least 397 records · Page 22Linked to original sources

Transient protection of human T-cells from human immunodeficiency virus type 1 infection by transduction with adeno-associated viral vectors which express RNA decoys.

RNA decoys are oligonucleotides corresponding to the TAR and RRE sequences of HIV which inhibit the HIV-encoded regulatory proteins Tat and Rev, respectively. Adeno-associated viral vectors encoding RNA decoys stably transduced into the human T-cell line CEM-SS expressed transactivating region (TAR) and Rev-responsive element (RRE) RNA decoys from tRNA polIII promoters at high levels, without any apparent deleterious effects on cell growth or expression of CD4. DNA blot analysis indicated that RNA decoy-encoding vectors were not rearranged and were integrated into the genomic DNA of selected cell lines. Vector DNA with the appropriate TAR and RRE sequences was isolated from transduced cell lines after prolonged growth in culture, further confirming that the vector DNA was present in a stable form through multiple cell cycles. Cell lines expressing TAR and RRE decoys transiently inhibited HIV gene expression and replication by 70-99% as determined by measurement of intracellular and extracellular HIV p24 production. Adeno-associated vectors encoding RNA decoys may be useful for gene therapy of HIV infection.

Cell Line↗

Sleep states, memory processes and synaptic plasticity.

There is now a substantial body of data to suggest a relationship between sleep states, particularly paradoxical sleep (PS) or rapid eye movement (REM) sleep, and learning. In animal studies, PS increases have been observed following acquisition in formal tasks and following exposure to enriched environments (EE). Further, PS deprivation at certain post-training times is known to impair memory for recently acquired tasks. PS deprivation following EE exposure has been reported to impair the neural changes normally observed. It is argued that the prolonged PS increases observed following either formal training or EE exposure reflect the same kinds of neural change. It is proposed that accelerated neural plasticity takes place during elevated post-training PS and is especially vulnerable to disruption at specific post-training time periods called PS windows. Further, it is proposed that similar processes take place in the post-training sleep of humans.

Animals↗

Early presentation of metastatic medullary carcinoma in multiple endocrine neoplasia, type IIA: implications for therapy.

A girl 5 years 11 months of age, belonging to an extensive kindred with multiple endocrine neoplasia, type IIA (MEN IIA), was found to have multifocal medullary thyroid carcinoma with metastasis in one paraglandular lymph node after positive findings on a calcium-pentagastrin stimulation test. Her sister, 3 years 8 months of age, also had an elevated calcitonin level, and thyroidectomy revealed C-cell hyperplasia and a focus of medullary thyroid carcinoma. These two cases underscore the need for prophylactic thyroidectomies in MEN IIA patients as young as 5 years of age and strict yearly provocative screening beginning at age 1 year.

Carcinoma, Medullary↗

A comparison of inhaled nitric oxide with intravenous vasodilators in the assessment of pulmonary haemodynamics prior to cardiac transplantation.

OBJECTIVE: Elevated pulmonary vascular resistance and transpulmonary gradient are predictors of increased perioperative mortality in patients undergoing orthotopic heart transplantation. Sodium nitroprusside and prostacyclin PGI2 are routinely used to assess the reversibility of pulmonary vascular resistance and transpulmonary gradient in heart transplant candidates, but their use is limited by their systemic vasodilatory effect. The aim of this study was to evaluate the systemic and pulmonary haemodynamic effects of low concentration (10 and 20 parts per million) inhaled nitric oxide in patients with severe heart failure with elevated transpulmonary gradient and pulmonary vascular resistance undergoing assessment for cardiac transplantation, and to compare the haemodynamic effects of inhaled nitric oxide with those of sodium nitroprusside and prostacyclin PGI2. METHOD: In 10 consecutive patients with elevated transpulmonary gradient (16+/-2 mm Hg) and pulmonary vascular resistance (3.6 +/-0.3 Wood units (WU)) nitric oxide (10 and 20 parts per million in 23% inspired oxygen (O2) via a tight fitting facemask) and increasing doses of intravenous sodium nitroprusside and prostacyclin were administered in a random, single-blinded fashion. RESULTS: Inhalation of nitric oxide (10 ppm) reduced the transpulmonary gradient (-7+/-2 mm Hg; P<0.01) and pulmonary vascular resistance (-1.8+/-0.4 WU; P<0.001) but did not affect the systemic vascular resistance (-0.3+/-1 WU) or mean systemic arterial pressure (-1.3 5 mm Hg). Sodium nitroprusside and prostacyclin reduced the transpulmonary gradient (-4.5+/-2 mm Hg; P<0.01 and -3.6+/-2 mm Hg; P<0.05), pulmonary vascular resistance (-1.5+/-0.4 WU; P<0.001 and -1.3+/-0.4 WU; P<0.01), systemic vascular resistance (-7+/-2 WU; P<0.01 and -7.2+/-2 WU; P<0.01) and mean systemic arterial pressure (-15+/-5 mm Hg; P<0.01 and -18+/-4 mm Hg; P<0.01). CONCLUSION: Low-concentration inhaled nitric oxide is as effective as sodium nitroprusside and prostacyclin in reducing transpulmonary gradient and pulmonary vascular resistance, and is highly pulmonary vasoselective.

Administration, Inhalation↗

A potent far-upstream enhancer in the mouse pro alpha 2(I) collagen gene regulates expression of reporter genes in transgenic mice.

We have identified three DNase I-hypersensitive sites in chromatin between 15 and 17 kb upstream of the mouse pro alpha 2 (I) collagen gene. These sites were detected in cells that produce type I collagen but not in cells that do not express these genes. A construction containing the sequences from -17 kb to +54 bp of the mouse pro alpha 2 (I) collagen gene, cloned upstream of either the Escherichia coli beta-galactosidase or the firefly luciferase reporter gene, showed strong enhancer activity in transgenic mice when compared with the levels seen previously in animals harboring shorter promoter fragments. Especially high levels of expression of the reporter gene were seen in dermis, fascia, and the fibrous layers of many internal organs. High levels of expression could also be detected in some osteoblastic cells. When various fragments of the 5' flanking sequences were cloned upstream of the 350-bp proximal pro alpha 2(I) collagen promoter linked to the lacZ gene, the cis-acting elements responsible for enhancement were localized in the region between -13.5 and -19.5 kb, the same region that contains the three DNase I-hypersensitive sites. Moreover, the DNA segment from -13.5 to -19.5 kb was also able to drive the cell-specific expression of a 220-bp mouse pro alpha 1(I) collagen promoter, which is silent in transgenic mice. Hence, our data suggest that a far-upstream enhancer element plays a role in regulating high levels of expression of the mouse pro alpha 2(I) collagen gene.

3T3 Cells↗

Herpes simplex virus-mediated activation of human immunodeficiency virus is inhibited by oligonucleoside methylphosphonates that target immediate-early mRNAs 1 and 3.

IE1 and IE3 mRNAs and their protein products (IE110 and IE175, respectively) were detected in HSV-1-infected U937 cells at 4-15 hours postinfection. In transient expression assays with infectious HIV or an HIV-LTR-directed chloramphenicol acetyltransferase construction (HIV-LTRcat), HSV-1 caused HIV activation (86.7% +/- 6.4% conversion). Electrophoretic mobility shift assays with DNA sequences that encompass the LBP-1 binding site revealed increased levels of DNA-protein complex formation with nuclear extracts from HSV-1 infected as compared with uninfected U937 cells. Novel bands were not seen. HSV-1 mutants respectively deleted in IE110 (dl1403) or IE175 (d120) activated HIV as well as wild-type virus. However, HSV-1-mediated activation was inhibited (26% conversion) by simultaneous treatment with oligonucleoside methylphosphonates (ONMP) that specifically inhibit expression of IE110 (IE1TI) or IE175 (IE3TI). ONMP did not inhibit activation when used individually (83.8% and 67.8% conversion with IETI1 and IE3TI, respectively). Combinations of mutant ONMP that do not inhibit IE110 or IE175 expression did not reduce the levels of HSV-1-mediated activation. These findings suggest that HSV genes IE1 and IE3 can independently activate HIV in monocytic cells and ONMP that target HSV IE genes can be used to inhibit HIV activation.

Antiviral Agents↗

Body-composition measurement in 9-11-y-old children by dual-energy X-ray absorptiometry, skinfold-thickness measurements, and bioimpedance analysis.

We compared, in 9-11-y-old children (n=43), three measures of body composition: dual-energy X-ray absorptiometry (DXA), skinfold thickness, and bioimpedance analysis (BIA). The intraclass correlation coefficient (ICC), Bland-Altman procedure, and Spearman rank correlation were used to determine test-retest reliabilities of the three methods and to compare methods. For DXA measurements, the rank correlation between fat-free soft tissue and fat-free mass (FFM) was > 0.99, indicating that bone mineral content did not provide independent information. Thus, subsequent analyses used the two-compartment model (ie, fat mass and FFM) for all three techniques, focusing especially on values for percentage of fat. The test-retest reliabilities for all methods were high (ICCs > 0.994 and no significant differences between trials 1 and 2). The range of individual differences from trial 1 to trial 2 and Bland-Altman limits of agreement suggested that the reliability was greatest for DXA, followed by BIA and skinfold-thickness measurement. The percentage of fat values for the three methods were highly intercorrelated (all Spearman r values > 0.83). However, there was a systematic tendency (P < 0.01) for DXA values (mean: 23.98) to be higher than those derived from skinfold-thickness measurements (mean: 21.05) and BIA (mean: 21.52). The variance in percentage of fat values for BIA was significantly smaller than that for the other two techniques. These findings, along with rather large limits of agreement derived from the Bland-Altman procedure, suggest that the methods should not be used interchangeably.

Absorptiometry, Photon↗

Assigning linkage haplotypes from parent and progeny genotypes.

Given the genotypes of parents and progeny, their haplotypes over several or many linked loci can be easily assigned by listing the allele type at each locus along the haplotype known to be from each parent. Only a small number (5-10) of progeny per family is usually needed to assign the parental and progeny haplotypes. Any gaps left in the haplotypes may be filled in from the assigned haplotypes of relatives. The process is facilitated by having multiple alleles at the loci and by using more linked loci in the haplotype and with more progeny from the mating. Crossover haplotypes in the progeny can be identified by their being unique or uncommon, and the crossover point can often be detected if the locus linkage map order is known. The haplotyping method applies to outbreeding populations in plants, animals and man, as well as to traditional experimental crosses of inbred lines. The method also applies to half-sib families, whether the genotypes of the mates are known or unknown. The haplotyping procedure is already used in linkage analysis but does not seem to have been published. It should be useful in teaching and in genetic applications of haplotypes.

Animals↗

False aneurysm of the superficial temporal artery: a surgical complication.

This case report illustrates the dramatic presentation of a previously unreported complication of surgery in the temporal region: development and rupture of a false aneurysm of the superficial temporal artery. This complication was related to the operation, the age of the patient, and split skin graft coverage of the superficial temporal artery.

Aged↗

Evaluation of ground cortical autograft as a bone graft material in a new canine bilateral segmental long bone defect model.

The recent orthopaedic literature reflects a growing number of bone graft substitutes and osteogenic growth factors under investigation in a number of animal models. We attempted to establish a well-controlled, large animal model of a segmental defect in a weight-bearing long bone by developing a bilateral diaphyseal radial defect model in the canine. We also evaluated the effectiveness of ground cortical autograft as a graft material. Twenty-three adult mongrel dogs underwent bilateral radial osteotomies with creation of a 2.0-2.5-cm diaphyseal defect on each side. All dogs received cancellous autograft (CAN) on one side, nine received no graft material (DEF) on the opposite side, and 14 received morselized cortical autograft (CORT) on the opposite side. Radii were stabilized by external fixation. Animals were followed radiographically at 6-week intervals to evaluate the healing process. Thirteen dogs were sacrificed at short-term follow-up (8-12 weeks postsurgery) and 10 at long-term (16-24 weeks). Biomechanical torsion testing to failure and histological evaluation were performed on each defect. All CAN radii achieved union (100%) while only one of nine DEF radii (11%) and none of 14 (0%) of CORT radii achieved union. Statistically significant differences in biomechanical parameters between both test groups and their corresponding autograft control radii were found. Histology revealed fibrous nonunions in the DEF and CORT radii. These results demonstrate that the bilateral canine radial defect model represents a consistent and reproducible model for bone healing of segmental defects in weight-bearing long bones and that ground cortical autograft is an ineffective graft material.

Animals↗

Thoracic aorta injuries: management and outcome of 144 patients.

Rupture of the thoracic aorta from blunt injury is often lethal. Methods of operative repair vary, based on the surgeon's preference and circumstances. The primary hypothesis of this study was that operative management choices would correlate with outcome. Data on demographics, injury mechanism, initial evaluation, diagnostic procedures, operative treatment, and outcome were obtained from chart review at the state's eight trauma centers. Rates of paraplegia and survival were compared for different methods of operative repair. Of 63,507 hospitalized trauma patients, 144 patients sustained thoracic aortic injury (incidence = 0.23%). Sixty-four died (44.1%), most of whom died in the emergency department (26) or the operating room (12). Eighty-six patients had complete operative data for analysis, including cross-clamp time and methods of repair. No patient in the group with a cross-clamp time of less than 35 minutes developed paraplegia (p = 0.02). For the patients with longer cross-clamp times, 6 of 14 patients (42.9%) undergoing clamp and sew repair developed paraplegia, as compared to 2 of 37 patients (5.4%) repaired on bypass (p = 0.005). This study suggests that the rate of paraplegia after repair of thoracic aortic injury can be minimized with short cross-clamp times or the use of bypass when long cross-clamp times can be anticipated.

Adolescent↗

New application of the gastrostomy button for clinical and urodynamic evaluation before vesicostomy closure.

PURPOSE: We report use of the Bard gastrostomy button to occlude vesicostomy and provide access for intermittent catheterization before closure in children with vesicostomy. Evaluation of bladder function in such children usually relies on radiographic and urodynamic studies, which may fail to predict bladder compliance, emptying and continence after closure. MATERIALS AND METHODS: Buttons were placed before vesicostomy closure in 1 boy with the prune-belly syndrome and 2 girls with cloacal anomalies 2.5 to 10 years old. The patients had undergone vesicostomy using the Blocksom technique soon after birth because of urinary infection, and impairment of bladder emptying and renal function. RESULTS: With the button in place bladder emptying, compliance, continence and possible upper tract changes could be evaluated during several weeks. Button coaptation to the vesicostomy was complete with no urine leakage around the device, allowing easy intermittent drainage through its channel. After 4 weeks the buttons did not have any encrustation or lithiasis and patients were free of urinary infection. Vesicostomy was closed in each patient and the period of temporary closure provided by the button was predictive of future bladder behavior. CONCLUSIONS: This new and original application of the gastrostomy button as a temporary vesicostomy closure may be useful to predict the clinical and urodynamic responses of a defunctionalized bladder in patients with vesicostomy who are candidates for urinary undiversion.

Child↗

Is there a best alternative to treating the obstructed upper pole?

PURPOSE: We addressed whether salvage of upper pole renal units in comparison to partial nephrectomy affects differential renal function in patients with a duplicated obstructed upper pole. MATERIALS AND METHODS: We retrospectively reviewed the records of all children who underwent surgery for a unilateral obstructed duplicated kidney at our institution from 1988 to 1995. Patients were evaluated with respect to postoperative complications, reoperation rate and percent change in differential renal function of the obstructed duplicated kidney, as determined by nuclear renography. RESULTS: We identified 46 patients with a unilateral obstructed upper pole of a duplicated kidney who were divided into 2 groups. Group 1 (12 patients) underwent an upper pole salvage procedure, that is ureteropyelostomy or ureteroureterostomy, and group 2 (31 patients) underwent partial nephrectomy. Three reoperations (25%) were performed in group 1 and 1 (4%) was done in group 2. Postoperative symptomatic urinary tract infections were diagnosed in 3 group 1 patients (25%) and in 2 (8%) in group 2. Average change in ipsilateral renal function in the 8 patients who underwent upper pole salvage procedures was 2.25 +/- 2.34% (range -6 to 12). In the 8 patients who underwent upper pole nephrectomy and who also had postoperative renal scans average change in function was -1.25 +/- 4.51% (range -23 to +16). CONCLUSIONS: There was no statistically significant loss of relative renal function in patients treated with partial nephrectomy and no significant gain in relative renal function in those treated with an upper pole salvage procedure. The reoperation rate was higher in the upper pole salvage than in the partial nephrectomy group (25 versus 4%). While not statistically significant, we believe that this rate is clinically important. We think that partial nephrectomy should remain the preferred treatment for most patients with obstructed duplicated kidneys.

Adolescent↗

Double onlay preputial flap for proximal hypospadias repair.

PURPOSE: We describe a new technique for primary repair of proximal hypospadias. The double onlay preputial flap combines the principles of onlay urethroplasty and the double face preputial flap, namely preservation of the urethral plate and use of a total preputial flap. MATERIALS AND METHODS: Common problems of classic onlay urethroplasty, including rotation and asymmetry of the penile shaft when the preputial flap is brought laterally around the shaft and the viability of the Byars flaps after dissecting the pedicle for the onlay flap, are avoided with this technique by passing the penis through a buttonhole incision in the pedicle of the total preputial flap. Onlay urethroplasty is performed using a secondary flap outlined from the total preputial flap. The remainder of the total preputial flap tissue is used to cover the ventral skin defect. RESULTS: Since June 1994, 18 patients 6 months to 9 years old (median age 10 months) underwent primary hypospadias repair with the double onlay preputial flap technique, representing 15% of all repairs performed. Complications included a urethrocutaneous fistula, persistent chordee, a recessed meatus and a urethral diverticulum in 1 patient each. In all cases complications were corrected surgically with minor procedures. No patient had urethral stricture. Functional and cosmetic results were satisfactory in all patients. CONCLUSIONS: This technique yields good functional and cosmetic results for proximal hypospadias repair.

Child↗

Physical training, lifestyle education, and coronary risk factors in obese girls.

The effects of supervised physical training (PT) and lifestyle education (LSE) on risk factors for coronary artery disease and non-insulin-dependent diabetes mellitus were compared in obese 7- to 11-yr-old black girls. The subjects were divided into two groups. The PT group (N = 12) completed a 5-d.wk-1, 10-wk, aerobic training program; and the LSE group participated in weekly lifestyle discussions to improve exercise and eating habits. The PT group showed a significant increase in aerobic fitness (P < 0.05) and decrease in percent body fat (P < 0.05), while the LSE group declined significantly more in dietary energy and percent of energy from fat (P < 0.05). Fasting insulin did not change significantly. The LSE group declined significantly more than the PT group in glucose (P < 0.05), and glycohemoglobin declined from baseline in both groups (P < 0.05). Lipid changes were similar in the two groups: total cholesterol/high density lipoprotein cholesterol (P < 0.01) and triglycerides (P < 0.05) declined, the low density lipoprotein (LDL)/apoproteinB ratio increased (which indicates a decrease in small dense LDL) (P < 0.05) and lipoprotein(a) increased (P < 0.05). Thus, the interventions were similarly effective in improving some diabetogenic and atherogenic factors, perhaps through different pathways; i.e., the PT improved fitness and fatness, while the LSE improved diet. Exercise and diet-induced changes in lipoprotein(a) require further investigation.

Child↗

Comparison of bronchoalveolar lavage and catheter lavage to confirm ventilator-associated lower respiratory tract infection.

Lower respiratory tract infection (LRTI) is a well recognised complication of artificial ventilation in intensive care units (ICU). Ideally, specimens for microbiological analysis should be obtained during bronchoscopy, but this is not always possible. Therefore, the microbiological diagnosis of lower respiratory tract infection by broncho-alveolar lavage (BAL) obtained during bronchoscopy was compared with catheter lavage (CL) with a balloon-tipped catheter. Adult patients with clinical evidence of lower respiratory tract infection in an adult ICU were randomly assigned to undergo BAL followed by CL or vice versa. Forty ml of normal saline 0.9% were instilled and then aspirated with a flexible bronchoscope to obtain BAL. A similar volume was instilled and aspirated with a 12-gauge Foley balloon-tipped catheter to obtain a CL sample. The number of inflammatory cells, epithelial cells and organisms seen by microscopy were quantified. Culture results were semi-quantified and classified as negative, positive, equivocal or contaminated. Seventy-nine paired specimens were obtained from 66 patients, including specimens from 10 patients taken on two or more occasions. Only 20% of BAL and 16% of CL had one or more epithelial cells and bacteria were seen in 26 BAL and 21 CL specimens, respectively; 35% of BAL and CL specimens were positive and there was a discrepancy in the culture result in only two cases. Staphylococcus aureus was the pathogen isolated most frequently and polymicrobial lower respiratory infection was diagnosed on 10 occasions (15%). CL fluid is as reliable as BAL in diagnosing lower respiratory tract infection in ICU. This approach does not require bronchoscopic expertise and utilises convenient laboratory techniques.

Adolescent↗