Biomedical subjects

S D Smith

Publications and source records attributed to S D Smith.

At least 91 records · Page 5Linked to original sources

PubMed1997

A long-term dose-response study of mitomycin in glaucoma filtration surgery.

OBJECTIVE: To establish the long-term, dose-response relationship between the concentration of and duration of exposure to mitomycin to a decrease in intraocular pressure (IOP) and fewer complications. METHODS: We performed a prospective double-masked, placebo-controlled, 1-year study evaluating the decrease in IOP and fewer complications of fornix-based trabeculectomy surgery in 300 eyes equally divided among therapy with placebo; mitomycin, 0.2 mg/ mL, applied for 2 minutes; mitomycin, 0.4 mg/mL, applied for 4 minutes; or mitomycin, 0.4 mg/mL, applied for 2 minutes. All of the eyes had vertical and horizontal cup-disc ratios greater than 0.7. RESULTS: We observed significant treatment-related differences in IOP, with a decrease in IOP in all 3 mitomycin-treated groups for all of the times beyond 1 month. The number of eyes achieving strict IOP control and the development of cataract suggest a possible dose-response effect for concentration and time of exposure. Progressive lens opacification was the most frequent complication in 54 eyes (18.1%). The incidence of progressive lens changes markedly increased in subjects receiving 4 minutes of mitomycin therapy. Cataract formation was unrelated to IOP. Other complications were rare. Macular folds developed in 6 patients, with visual acuity returning to better than 20/40 in all but 1 patient. CONCLUSIONS: A possible dose-response relationship seemed to exist between the concentration of and duration of exposure to mitomycin. Length of exposure seems to be more important than concentration. The benefits of additional decreases in IOP must be weighed against the potential for increases in the risk of complications.

Antibiotics, Antineoplastic↗

PubMed1997

TUNEL-positive ganglion cells in human primary open-angle glaucoma.

OBJECTIVE: To determine whether retinal ganglion cell death in primary open-angle glaucoma occurs by apoptosis. METHODS: Eighteen eyes of 17 subjects with documented primary open-angle glaucoma were compared with 21 control eyes that were group matched for age, race, and sex. Staging of glaucoma severity was performed by histologic optic nerve evaluation. Fixed, paraffin-embedded retinal sections were assayed by the TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (UTP)-biotin nick end-labeling) method to detect the internucleosomal DNA fragmentation that is characteristic of apoptosis. RESULTS: A positive TUNEL reaction was observed among ganglion layer cells in 10 of 18 cases with glaucoma, compared with 1 of 11 control cases without confounding systemic disease (5 control eyes were excluded owing to artifactual staining and 4 eyes had confounding systemic disease). Sections containing more than 250,000 cells in the ganglion cell layer were examined in cases and controls. The frequency of TUNEL-positive cells in the ganglion cell layer in cases with glaucoma was 1.76 per 10,000, or 15.2 times greater than the control frequency from individuals without confounding disease (P < .001; 95% CI, 2.46-623). Eyes without glaucoma from subjects with diabetes and amyotrophic lateral sclerosis showed more positive cells than other controls. CONCLUSION: Apoptosis seems to be a mechanism of cell death in human eyes with primary open-angle glaucoma.

Aged↗

PubMed1997

Effect of cataract extraction on the results of automated perimetry in glaucoma.

OBJECTIVE: To investigate the effect of cataract extraction on the results of automated perimetry in persons with glaucomatous visual field loss. SUBJECTS: Subjects from a retrospective study of visual field progression who underwent cataract extraction during follow-up were identified. Subjects came from the glaucoma service of a hospital-based tertiary referral center. METHODS: Subjects had at least 7 Humphrey 24-2 or 30-2 visual fields over 5 years or more, with an abnormal glaucoma hemifield test result on the first 2 examinations. Visual field data were transferred to a microcomputer and comparison of the visual fields immediately before and after cataract extraction was performed. RESULTS: Sixty-five eyes of 50 subjects (mean age, 71.8 years) were included in the analysis. A mean improvement in mean deviation (MD) of 1.68 dB (P<.001), and a mean worsening in corrected pattern SD (CPSD) of 0.54 dB (P=.09) was observed. The mean unweighted change in threshold in the 52 points of program 24-2 was 1.58 dB, corresponding to a 43.9% increase in sensitivity. A significant correlation between improvement in visual acuity and improvement in MD was also found. A mean increase in CPSD of 1.61 dB (P=.005) occurred in subjects with dense scotomas (minimum threshold value < or = 5 dB) and preoperative CPSD of 8 dB or less. CONCLUSIONS: In persons with glaucomatous visual field defects, cataract extraction produces only a modest improvement in MD. After cataract surgery, the CPSD index worsened in many subjects with dense scotomas. This suggests that the development of cataract can mask progressive glaucomatous visual field loss in such persons.

Aged↗

PubMed1997

A t(6;12)(q23;p13) results in the fusion of ETV6 to a novel gene, STL, in a B-cell ALL cell line.

ETV6 (TEL) is rearranged in various types of hematologic malignancies. The B-cell precursor acute lymphoblastic leukemia (ALL) cell line SUP-B2 has a t(6;12)(q23;p13) involving ETV6 at 12p13 and a submicroscopic deletion of the other ETV6 allele. The reciprocal translocation results in the fusion of ETV6 to a previously unknown gene at 6q23, which we named STL (six-twelve leukemia gene). Both reciprocal fusion transcripts can be detected: On the der(6) chromosome, the ETV6/STL mRNA shows an apparently out of frame fusion of ETV6 at nucleotide 187 to STL, which would result in the addition of 14 amino acids to the first 54 amino acids of ETV6. On the der(12) chromosome three different variants of the STL/ETV6 fusion mRNA could be detected; variable size segments were inserted at the breakpoint between STL and ETV6 exon 3. One of these variants could give rise to a protein in which the first 54 amino acids of ETV6 are replaced by 12 amino acids from one of the STL short open reading frames. Sequence analysis of a 1.4 kb STL cDNA clone from a skeletal muscle library revealed no long open reading frames. This cell line will be very useful in studying the different mechanisms by which alterations of ETV6 contribute to leukemogenesis and in testing the hypothesis that ETV6 might act as a tumor suppressor gene.

Amino Acid Sequence↗

PubMed1997

Is nasogastric tube decompression necessary after major abdominal surgery in children?

Nasogastric (NG) decompression has traditionally been used after major abdominal surgery in pediatric patients. This study was designed to determine if NG tubes could be routinely omitted in pediatric patients undergoing major abdominal procedures. Between January 1993 and December 1995, 83 patients had follow-up prospectively without NG decompression after a variety of major abdominal surgeries. NG tubes were inserted for persistent vomiting or abdominal distension. Exclusion criteria included bowel obstruction, intestinal atresia, and perforation of the stomach or duodenum. Ages ranged from 13 days to 22 years. Seventy-four patients (89%) were treated successfully without postoperative NG decompression. There were no cases of pneumonia, wound dehiscence, anastomotic leak, or delay in return of gastrointestinal function. Nine patients required NG tubes for persistent vomiting or abdominal distension. An anastomotic leak developed in one patient after endorectal pull-through. NG decompression is unnecessary after most major abdominal operations in pediatric patients. The endorectal pull-through may represent a group of patients that benefit from routine decompression.

Adolescent↗

PubMed1997

The protective role of gastric acidity in neonatal bacterial translocation.

The acid environment of the stomach serves as an important defense against intestinal colonization by potentially pathogenic bacteria. The purpose of this study was to examine the effect of increased gastric pH on bacterial translocation in a neonatal rabbit model. Fifty-nine rabbit pups were delivered by cesarean section and randomly divided into normal acid (NA) and reduced acid (RA) groups. All were gavage fed and challenged with Enterobacter cloacae, 1 x 10(6) CFU/mL. The RA group received ranitidine, 20 mg/kg/d with all feeds. Gastric pH was measured by pH probe before and 4 hours after bacterial challenge. Mesenteric lymph node (MLN), spleen, liver, midjejunum, and cecum were harvested for culture at 72 hours. Gastric pH in the RA group was significantly increased before and 4 hours after the bacterial challenge. The incidence of bacterial translocation to the MLN, spleen, and liver was significantly higher in the RA group. Log cecal and jejunal colony counts were significantly increased in the RA animals. The authors conclude that the gastric acidity is protective against intestinal colonization and translocation of potentially pathogenic bacteria in this neonatal rabbit model.

Animals↗

PubMed1997

Pediatric surgeons on the Internet: a multi-institutional experience.

An estimated 24 million people, or 11% of the North American population over 16 years of age, use the Internet. An estimated 40% of households have computers, and 37 million people have Internet access. The experience of three pediatric surgery Internet sites are reviewed to evaluate current practices and future potential of the Internet to practicing pediatric surgeons. The sites reviewed are the Pediatric Surgery Bulletin Board System (BBS), the Pediatric Surgery List Server, and the Pediatric Surgery Website. Statistics were collected at each site to characterize the number of users, traffic load, topics of interest, and times of peak use. There are currently 79 subscribers to the Pediatric Surgery BBS and 100 subscribers to the Pediatric Surgery List Server. The average user of the BBS is a young man who has placed an average of 52 calls to the BBS since joining. There have been 1413 Internet electronic mail messages sent. Twenty-five percent of the traffic has been related to clinical problems and 5% to research, teaching, and career issues. Traffic at this site has been increasing exponentially with most of the dialogue concentrated on clinical issues and problem cases. In a 3-month period the Pediatric Surgery Website received 16,270 hits. The most commonly accessed areas include an electronic mail directory, case studies, the job board, information on the pediatric surgical residency, and information on upcoming meetings. Pediatric surgeons are exploring the Internet and using available pediatric surgery resources. The scope of professional information available to pediatric surgeons on the Internet is still limited but is increasing rapidly. The Internet will impact the way physicians practice medicine through education and communication.

Computer Communication Networks↗

PubMed1997

Effect of long-term oral L-arginine on the nitric oxide synthase pathway in the urine from patients with interstitial cystitis.

PURPOSE: We attempted to determine whether oral L-arginine, the substrate for nitric oxide synthase, increases nitric oxide synthase activity and cyclic guanosine monophosphate (cGMP) levels in the urine from interstitial cystitis patients. Nitric oxide and cGMP are decreased in urine from interstitial cystitis patients and both induce smooth muscle relaxation and immunological responses. Increasing urinary nitric oxide and cGMP may ameliorate interstitial cystitis symptoms. MATERIALS AND METHODS: Eight patients with interstitial cystitis were given L-arginine (1,500 mg. a day) orally for 6 months. Before and during treatment nitric oxide synthase activity and inducible nitric oxide synthase protein, cGMP, nitrate plus nitrite and interleukin 8 (IL-8) levels were measured in urine. RESULTS: After 2 weeks to 1 month of oral L-arginine treatment, urinary levels of nitric oxide synthase related enzymes and products increased significantly, while levels of the cytokine IL-8 were not changed significantly. IL-8 was significantly elevated in interstitial cystitis patients with leukocyte esterase positive urine. CONCLUSIONS: Long-term oral administration of L-arginine increases nitric oxide related enzymes and metabolites in the urine of patients with interstitial cystitis, which is associated with a decrease in interstitial cystitis related symptoms.

Administration, Oral↗

PubMed1997

Growth inhibition of B-cell precursor acute lymphoblastic leukemia cell lines by monocytes: a role for prostaglandin E2.

Leukemic cell lines have proven invaluable in the molecular analysis of recurring chromosomal translocations but the optimal methods for leukemia cell line establishment are unknown. During in vitro culture, most B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells die within 1 week at least partially mediated by inhibitors elaborated by peripheral blood mononuclear cells (PB MNCs) present within the leukemia sample. In experiments reported here, cyclooxygenase inhibitors (indomethacin and meclofenamic acid) blocked the PB MNC-mediated inhibition of BCP-ALL proliferation. Also, prostaglandin E2 (PGE2) was detected in supernatants from PB MNC cultures. When PGE2 was mixed directly with BCP-ALL cells, proliferation decreased significantly. Under the culture conditions used, PB MNCs secreted PGE2 which appears to be one of the major inhibitors of BCP-ALL growth in vitro.

Adult↗

PubMed1997

Phacoemulsification at King Khaled Eye Specialist Hospital--the experience of the past.

OBJECTIVE: To study the outcome of phacoemulsification (PE) compared to standard extracapsular surgery before the introduction of state-of-the-art techniques (capsulorhexis, hydrodissection, nuclear cracking, nuclear chopping, sutureless incisions) and sophisticated equipment. STUDY DESIGN: Charts from 375 patients (453 eyes) undergoing PE between 1984 and 1989 were randomly selected and studied retrospectively. A minimum age of 35 years, and a minimum follow-up of three months were required. SETTING: A large eye hospital in the Kingdom of Saudi Arabia staffed with an international faculty of ophthalmic surgeons. PATIENTS: Patients over 35 years of age undergoing PE for immature, mature and traumatic cataract. MAIN OUTCOME MEASURES: Postoperative visual acuity, and rate or frequency of intraoperative complications. RESULTS: 66.5% achieved visual acuity of 20/40 or better, which compares favourably with the 36.5% of eyes reaching this level of visual acuity after mainly standard extracapsular cataract surgery in another study at our hospital. Posterior capsule ruptures occurred in 7.5% and vitreous loss in 5.5%. Other ocular disease (odds ratio 7.51 confidence interval 4.43-12.7) and intraoperative complications (odds ratio 2.97 confidence interval 1.38-6.42) were statistically significant predictors for final visual acuity of under 20/40 (p = < 0.001 and 0.005 respectively). CONCLUSION: The outcome of PE was better than that of standard extracapsular cataract extraction in the same setting. However, since PE appeared to be used selectively, no clear advantage compared to extracapsular cataract extraction is evident in the period before the introduction of modern state-of-the-art PE-techniques.

Adult↗

PubMed1997

Time course of pronuclear deoxyribonucleic acid synthesis in parthenogenetically activated bovine oocytes.

The progress of pronuclear DNA synthesis was monitored by the radioactive precursor 3H-thymidine during the first cell cycle of parthenogenetically activated bovine oocytes. Bovine oocytes were exposed to Ca2+ ionophore A23187 at 24, 30, or 36 h after the onset of in vitro maturation. Young 24-h oocytes were subsequently cultured for 6 h in the protein synthesis inhibitor, cycloheximide (CHX), to ensure similar rates of activation (96-100%) and pronuclear formation (93-97%) among all groups of oocytes. Subsequent autoradiographic experiments revealed a slightly, but not significantly, accelerated start of DNA synthesis in aged (36 h) oocytes. Maximum levels of DNA labeling were reached within 4 h regardless of oocyte maturation age and persisted for 4 h in 30-h oocytes compared to 2 h in 36-h and 24-h oocytes. The period of DNA synthesis lasted for a total of 12-14 h in all groups of oocytes, and the duration of S-phase was less than 6 h. Since rates of pronuclear formation (58%) and labeling (58%) corresponded to each other, it is argued that only a fully developed pronucleus can synthesize DNA. Oocyte labeling performed in the presence of CHX revealed the capability of CHX to inhibit DNA synthesis up to 8 h postactivation. Removal of CHX by washing when the majority (94%) of oocytes had formed a fully developed pronucleus (at 8 h postactivation) led to the synchronous start of DNA synthesis within 1.5-2 h post-CHX culture. This concomitantly defined the time required for synthesis of vital proteins needed for the entry into S-phase and/or DNA replication. The prolonged exposure of activated oocytes to CHX (10-12 h) negatively affected the pattern of DNA synthesis. The start of DNA synthesis was postponed and reduced pronuclear labeling was observed. In addition, CHX-treated oocytes often exhibited a characteristic punctate pattern of pronuclear labeling in which silver grains were accumulated into clusters. In conclusion, the present results provide knowledge about timing and a possible synchronization of DNA synthesis in parthenogenetically activated bovine oocytes.

Animals↗

PubMed1997

Improvement in interstitial cystitis symptom scores during treatment with oral L-arginine.

PURPOSE: Urinary nitric oxide synthase activity is decreased in patients with interstitial cystitis. Since nitric oxide may be an important determinant of the symptoms and immunological responses associated with interstitial cystitis, patients with this disease were treated with oral L-arginine, the substrate for nitric oxide synthase. MATERIALS AND METHODS: Ten patients took 1.5 gm. L-arginine orally daily for 6 months. Interstitial cystitis symptoms were surveyed before and during the 6-month trial. RESULTS: Oral L-arginine treatment resulted in a significant decrease in urinary voiding discomfort, lower abdominal pain and vaginal/urethral pain. Urinary frequency during the day and night also significantly decreased. CONCLUSIONS: This self-controlled study provides evidence that long-term oral L-arginine improves interstitial cystitis related symptoms.

Adult↗

PubMed1997

Genetic analysis of dyslexia and other complex behavioral phenotypes.

In this review, we discuss recent data on the genetics of developmental dyslexia and consider broader issues involved in the search for genes influencing complex behavioral phenotypes. These issues include 1) the need for a sophisticated analysis of the phenotype and the need for interdisciplinary collaboration between geneticists and cognitive neuroscientists, 2) the likelihood of genetic heterogeneity and non-Mendelian inheritance and the necessity for linkage methods to deal with these issues, and 3) how association analyses complement linkage analyses.

Diabetes Mellitus, Type 1↗

PubMed1997

The retirement transition and the later life family unit.

The purpose of this investigation was to determine to what extent family worldview and problem-solving communication style influence individual and family unit adaptation during retirement. A cross-sectional correlational survey design utilized Pearson correlations and stepwise multiple regressions. The sample consisted of 368 individuals representing 184 later life family units. Operationalized as family unit data, family worldview and family problem-solving communication style were examined in two series: (1) with outcome variable of family unit adaptation and (2) with outcome variable of individual adaptation. Scoring of family unit data was conceptually, procedurally, and analytically congruent. The investigation extended McCubbins' work into the later life family unit giving empirical support for two propositions of the Resiliency Model (M.A. McCubbin & H.I. McCubbin, 1993). This investigation also extended A. Antonovsky's (1987) work as the second study to apply the Antonovsky Sense of Coherence Scale to a family measurement. Conclusions are that although the way the family views the world is important during retirement, being affirmed by family members is more important. The investigation highlights the importance of a positive problem-solving communication style for a positive level of family adaptation. Individual adaptation during retirement was more influenced by family worldview.

Adaptation, Psychological↗

PubMed1997

Establishment of the block against sperm penetration in parthenogenetically activated bovine oocytes matured in vitro.

The ability of a single electric pulse to mimic a block against sperm penetration in bovine oocytes matured in vitro was investigated. Confocal laser scanning microscopy detected a global loss of spots, presumed to be cortical granules, stained with Lens culinaris agglutinin, in pulsed oocytes. Transmission electron microscopy revealed that cortical granule exocytosis occurred within 1 min of stimulation and the number of remaining cortical granules was significantly reduced in all pulsed oocytes. The ability of pulsed oocytes to undergo fertilization in vitro was also affected, as only 31% of the pulsed oocytes were penetrated compared with 87% in the control group. Since incidences of penetration in pulsed oocytes (31%), and of polyspermy in control oocytes (18%) did not differ and were highly correlated (P = 0.009) among trials (n = 15), the induced block is considered to be comparable with the natural block triggered by a spermatozoon. The increased resistance of the zona pellucida to pronase E observed in pulsed oocytes suggests that the induced block depends, at least partly, on modifications of zona pellucida glycoproteins. Finally, the majority (66%) of pulsed, penetrated oocytes did not form male pronuclei, probably as a consequence of asynchrony between the formation of female pronucleus and sperm penetration. The reduced ability of the cytoplasm to induce the formation of a male pronucleus was accompanied by a fall in histone H1 kinase activity to basal values by 3 h after stimulation. These results demonstrate that a single electric pulse can induce a block against sperm penetration similar to that of the spermatozoon itself.

Acrosome↗

PubMed1997

Subtalar arthrorisis and associated procedures.

Not all flatfeet require surgical correction. Through a careful history obtained from the child's parents, useful clues may be gathered pertaining to the disability arising from the flatfoot. There are three distinct classifications of flexible pes pronatus that require specific procedures for correction of the primary deformity. The STA-Peg, alone or in combination with other medial arch procedures, is used for correction of hindfoot pronation in the coronal planar dominant foot. The postoperative disability associated with the STA-Peg is relatively minimal, and complications are usually due to improper insertion of the implant.

Adolescent↗

PubMed1997

The initial complication rate of phacoemulsification in India.

PURPOSE: This study was designed to investigate the feasibility of teaching experienced surgeons to perform phacoemulsification in India, a cataract-endemic area. Complications occurring during surgery and the first postoperative day were documented and evaluated. METHODS: During a 1-month period, at the Aravind Eye Hospital in Madurai, India, the first 100 consecutive cataract operations performed by each of three experienced surgeons (a total of 300 cases), using phacoemulsification were prospectively evaluated. Multiple logistic regression was used to identify factors associated with intraoperative and postoperative complications. RESULTS: The mean age of patients was 57.4+/-9.3 years. The median best corrected preoperative visual acuity was 20/80. Mean surgical and phacoemulsification times were 15.8+/-3.7 minutes and 2.2+/-1.5 minutes, respectively. Complications occurred in 65 (21.7%) eyes. The most common was a rent in the posterior capsule, occurring in 40 (13.3%) eyes. There were significant variations in complication rate and in surgical time among the surgeons. The risk of experiencing a complication decreased as the number of phacoemulsifications performed increased. An increased risk of complications was associated with worse preoperative visual acuity and increasing patient age. CONCLUSIONS: With each successive case, the chances of experiencing a complication decreased 1%. Acceptable results were obtained within 1 month of performing the first phacoemulsification.

Adult↗

PubMed1997

Accuracy of fine needle aspiration biopsy of the breast.

Fine needle aspiration biopsy (FNAB) has become a widely used and accepted procedure to detect benign and malignant lesions of the breast. In the past, highly invasive procedures were used in the investigation of suspect breast tumors. Surgical excision was the method of choice during this period often requiring hospitalization of the patient. However, the recent introduction of FNAB has allowed a less traumatic approach for such investigations. Due to pressures from Health Management Organizations (HMO's), FNAB is presently the method of choice allowing for decreased patient trauma, expense, and ability of the procedure to be performed on an outpatient basis. Although highly accepted by most clinicians, others suggest that FNAB should perform diagnostically at a level equivalent or higher than that obtainable by frozen tissue sectioning procedures. This study was designed to evaluate the diagnostic ability of FNAB. Four-hundred twenty-seven patients underwent FNAB during 1993-94 at the University of Mississippi Medical Center. Of those patients, two hundred thirty-seven also underwent corresponding surgical biopsies. Sensitivity (88%), specificity (96%), a false positive rate (4%), and a false negative rate (12%) were calculated from the data and reported. In conclusion, the diagnostic accuracy of FNAB of the breast determined in this study shows the significance of the procedure.

Biopsy, Needle↗