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Biomedical subjects

D Shin

Publications and source records attributed to D Shin.

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

Congenital absence of the vas deferens: incomplete penetrance of cystic fibrosis gene mutations.

PURPOSE: We evaluated the penetrance of cystic fibrosis gene mutations for the clinical phenotype of congenital bilateral absence of the vas deferens. MATERIALS AND METHODS: We retrospectively reviewed the fertility status of 244 brothers of 105 men with congenital bilateral absence of the vas deferens. Testing for the most common cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and for haplotype analysis of the intron 8/polythymidine segment was recommended for all men with congenital bilateral absence of the vas deferens. RESULTS: Of 244 brothers of men with congenital bilateral absence of the vas deferens 131 were eligible for assessment of fertility. Of the 131 evaluable brothers only 7 (5%) were found to have congenital bilateral absence of the vas deferens. This prevalence is 5 times lower than that predicted for congenital bilateral absence of the vas deferens (25%) based on the autosomal recessive inheritance pattern seen in classical cystic fibrosis. For couples in which the man has congenital bilateral absence of the vas deferens and the female partner tests negative for standard CFTR gene mutations including 5T analysis, the maximum risk of having a child with congenital bilateral absence of the vas deferens is less than 1.0%. CONCLUSIONS: Our data are consistent with incomplete penetrance for the congenital bilateral absence of the vas deferens phenotype after inheritance of cystic fibrosis gene mutations, even after adjusting for environmental factors and wolffian anomalies. Incomplete penetrance may account for a low prevalence of congenital bilateral absence of the vas deferens in the population and may lower the risk of having a child with congenital bilateral absence of the vas deferens for couples undergoing sperm retrieval and assisted reproductive techniques.

Congenital Abnormalities↗
PubMed1996

Wavelength dependence of cell cloning efficiency after optical trapping.

A study on clonal growth in Chinese hamster ovary (CHO) cells was conducted after exposure to optical trapping wavelengths using Nd:YAG (1064 nm) and tunable titanium-sapphire (700-990 nm) laser microbeam optical traps. The nuclei of cells were exposed to optical trapping forces at various wavelengths, power densities, and durations of exposure. Clonal growth generally decreased as the power density and the duration of laser exposure increased. A wavelength dependence of clonal growth was observed, with maximum clonability at 950-990 nm and least clonability at 740-760 nm and 900 nm. Moreover, the most commonly used trapping wavelength, 1064 nm from the Nd:YAG laser, strongly reduced clonability, depending upon the power density and exposure time. The present study demonstrates that a variety of optical parameters must be considered when applying optical traps to the study of biological problems, especially when survival and viability are important factors. The ability of the optical trap to alter either the structure or biochemistry of the process being probed with the trapping beam must be seriously considered when interpreting experimental results.

Animals↗
PubMed1996

Urogenital anomalies in men with congenital absence of the vas deferens.

PURPOSE: We evaluated urogenital anomalies in men with congenital absence of the vas deferens. METHODS AND MATERIALS: A retrospective review was done of 104 subfertile men with congenital absence of the vas deferens (84 bilaterally and 20 unilaterally). RESULTS: Of men with unilateral or bilateral congenital absence of the vas deferens 26 and 11%, respectively, had renal agenesis. Of men with unilateral congenital absence of the vas deferens and infertility 80% had genitourinary anamalies affecting the contralateral testis. No man with congenital absence of the vas deferens and renal anomalies had cystic fibrosis transmembrane-conductance regulator (CFTR) gene mutations detected. CONCLUSIONS: Other urogenital anomalies are common for men with congenital absence of the vas deferens. CFTR gene mutations frequently contribute to maldevelopment of the vas deferens but vasal agenesis can occur without any evidence of CFTR defects. CFTR abnormalities are rarely detected in men with congenital absence of the vas deferens and renal anomalies.

Cryptorchidism↗
PubMed1995

Topical apraclonidine hydrochloride in eyes with poorly controlled glaucoma. The Apraclonidine Maximum Tolerated Medical Therapy Study Group.

OBJECT: We determined whether the addition of topical apraclonidine hydrochloride to eyes receiving maximal medical therapy, with inadequate intraocular pressure (IOP) control, and scheduled to undergo surgery, could adequately lower IOP, postponing the need for surgical intervention. DESIGN: A prospective 90 day, multi-centered, placebo-controlled, doublemasked parallel study. PATIENTS: We enrolled 174 glaucoma patients with inadequate IOP control on maximally tolerated medical therapy. All were candidates for either laser trabeculoplasty or invasive surgical intervention. We enrolled only one eye per patient. INTERVENTIONS: We continued to administer maximum-tolerated medical therapy for glaucoma. Patients took the study medication every eight hours. Study medications were either apraclonidine hydrochloride 0.5% or placebo (apraclonidine's vehicle). MAJOR OUTCOME MEASURES: We evaluated IOP, IOP change from baseline, and the number of eyes requiring surgery after the addition of study medication. RESULTS: Sixty one percent of patients treated with apraclonidine maintained adequate IOP control throughout the study, avoiding additional surgery compared to 33.9% patients treated with placebo (P < .001). Apraclonidine treatment resulted in significantly more patients achieving either an additional > or = 20% reduction in IOP from baseline (resulting in an IOP < or = 20 mm Hg) (P < 0.05). The most common ocular complications were conjunctival hyperemia (12.6%), itching and foreign body sensation (6.8%), and tearing (4.5%). The most frequent non-ocular adverse events related to apraclonidine were dry mouth (4.5%) and unusual taste perception (2.2%). CONCLUSIONS: Apraclonidine appears safe and efficacious. It significantly lowered IOP when used in combination with a patient's maximum tolerated medical therapy. This delayed or prevented further glaucoma surgery for at least 90 days in approximately 60% of treated patients.

Administration, Topical↗
PubMed1993

Blood-brain barrier permeability and the brain extracellular space in acute cerebral inflammation.

The diffusion properties of the brain cortical extracellular space have never been examined in models of inflammation, even though inflammation can cause increased blood-brain barrier permeability. Uptake of intravascular 125I-labelled albumin and the diffusion of the tetramethylammonium ion within the brain extracellular space was measured in an experimental brain abscess to determine the effect of acute inflammation upon blood-brain barrier permeability and diffusion properties of the cortical extracellular space. The blood-brain transfer constant for albumin was increased in the abscess region, indicating that an increase in blood-brain barrier permeability occurred in animals inoculated with a weakly pathogenic strain of Staphylococcus aureus. The volume fraction of the extracellular space, as measured by the diffusion of tetramethylammonium ion, ranged from 0.19 to 0.23 in bacteria inoculated subjects and from 0.21 to 0.22 in controls. The tortuosity of the extracellular space ranged from 1.40 to 1.42 in bacteria inoculated subjects and was 1.39 in controls. These results showed that the volume fraction and tortuosity of the cortical extracellular space were not affected by inflammation even though vascular permeability was increased. This result was supported by the finding that brain water content, measured in the same animals, was increased to a non-significant extent in the bacteria inoculated subjects. These findings lead to the conclusion that acute inflammation induced by a weak pathogen can cause increased blood-brain barrier permeability without a significant change in the diffusion properties of the brain cortical space.

Animals↗
PubMed1993

Health care for the homeless: a public concern.

The number of homeless people in the nation and New Orleans continues to increase. It is an important problem for all citizens but is especially so for the social and medical care agencies. As physicians we are morally bound to help the less fortunate of our communities, and we must also protect the community from the illnesses to which the homeless may be more susceptible. However, because very little is accurately and reliably known about the homeless in New Orleans, little can be efficiently done to aid them. We report the results of our brief surveys to stimulate concern and action in the medical community for these unfortunate people.

Adolescent↗
PubMed1993

Whatever happened to abstracts from different sections of the association for research in vision and ophthalmology?

PURPOSE: The authors investigated the fate of abstracts from each ARVO section (May 1985 meeting), the overall publication percentage, and the journals in which the abstract-derived articles were published. METHODS: They performed a MEDLINE search by first author for 25 or 26 randomly selected abstracts from each section to identify those that led to full-length articles in peer-reviewed journals. RESULTS: Overall, 63% of abstracts led to full-length articles in peer-reviewed journals within our search period of 87 months. The publication rate of oral presentation abstracts (68%) was significantly higher than that of poster presentation abstracts (56%). A greater proportion of basic science-oriented abstracts (67%) led to publication than the clinically oriented abstracts (56%). The rate of publication was lowest for the Cornea section (40%) and highest for Physiology and Pharmacology (80%) and Biochemistry (76%). The abstract-derived articles were published in 67 different peer-reviewed journals, with 43% of the articles appearing in only five journals. CONCLUSIONS: The fact that the majority of abstracts led to full-length articles supports ARVO's goal of a large interdisciplinary appeal with the exchange of ideas among different investigators.

Congresses as Topic↗
PubMed1992

Fibrillar collagen-biphasic calcium phosphate composite as a bone graft substitute for spinal fusion.

The osteoconductive capacity of fibrillar collagen-biphasic calcium phosphate composition was compared to autogenous bone in a canine spinal fusion model. All animals underwent a standard intervertebral body fusion (L2-L4) with rigid internal fixation and received either autogenous bone alone or a mixture of the ceramic and autogenous bone (3:1) as the graft material. Animals were followed for 12 months and the quality of fusion in each animal assessed by biomechanical testing and histological analysis. The fused L2-L4 segment of each dog was embedded in bone cement and mounted in a specially designed mechanical tester for testing in flexion, extension, and side bending. Overall, the mean rigidity of the fusion mass was not significantly different between the two groups [10.5 +/- 4.1 (SD) for autogenous bone vs. 11.3 +/- 1.7 for the ceramic plus autogenous bone, p greater than 0.05]. Similar findings were obtained for mean bending moment, compressive load, angular deformation, and energy absorbed for the two groups. Histological analysis was performed on transverse nondecalcified specimens. Quantitation of bone ingrowth using back-scattered electron imaging disclosed no significant differences in the amount of new bone formed at the graft site between autogenous bone and the ceramic plus autogenous bone recipients (23.4 +/- 10% vs. 25.8 +/- 8.8%) when correction for the autogenous bone volumes was performed. Light microscopic analysis of toluidine blue-stained transverse sections demonstrated new bone growth around and through the ceramic bone graft material. These results suggest that use of a collagen-biphasic calcium phosphate ceramic and autogenous bone mixture (3:1) provides a suitable osteoconductive alternative to the use of autogenous bone and results in the formation of a mechanically competent fusion mass not significantly different from that obtained with autogenous bone alone.

Animals↗
PubMed1989

Management alternatives for post-polio respiratory insufficiency. Assisted ventilation by nasal or oral-nasal interface.

Post-poliomyelitis patients may develop insidious respiratory failure. Chronic alveolar hypoventilation symptoms are often misdiagnosed and the condition is frequently treated inappropriately by oxygen therapy. Physicians are often at a loss to offer assisted ventilation by noninvasive methods and tracheostomy and long-term tracheostomy intermittent positive pressure ventilation is often refused. We studied the use of two noninvasive positive airway pressure alternatives for the nocturnal ventilatory support of 31 post-poliomyelitis patients. These methods were intermittent positive pressure ventilation via nasal access (NIPPV) and via a strapless oral-nasal interface (SONI IPPV). The use of custom fabricated interfaces was also evaluated. Practical alternatives for assisted daytime ventilation included glossopharyngeal breathing, the pneumobelt ventilator and mouth intermittent positive pressure ventilation. Overnight sleep monitoring was performed on 10 patients breathing autonomously or with body ventilators then repeated on NIPPV and/or SONI IPPV. The mean sleep oxygen saturation (SaO2) increased from 87.5 +/- 9.1% on unassisted breathing or body ventilators to 96.2 +/- 2.0% (P less than 0.01) on NIPPV or SONI IPPV. Of 12 other patients with a mean vital capacity of 472 +/- 480 ml and no significant free time supine, 11 patients also maintained SaO2 greater than 94% during sleep supine on NIPPV and/or SONI IPPV. Twenty-one patients have been on nocturnal NIPPV for an average of 23 (3-70) months. Six have been on nocturnal SONI IPPV for an average of 35 (5-66) months. All patients' hypoventilation symptoms were relieved. In conclusion, NIPPV and SONI IPPV can improve the nocturnal ventilation of post-poliomyelitis patients with chronic alveolar hypoventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Levobunolol vs timolol for open-angle glaucoma and ocular hypertension.

A group of 162 patients with chronic open-angle glaucoma or ocular hypertension were treated twice daily for up to 15 months with one of the following topical ophthalmic solutions: 0.5% levobunolol, 1% levobunolol, or 0.5% timolol. Overall mean reductions in intraocular pressure were 8 mm Hg for patients receiving 0.5% levobunolol or timolol and 8.2 mm Hg for patients receiving 1% levobunolol. There were no significant differences between levobunolol and timolol in mean reductions in intraocular pressure, percent of patients with adequately controlled intraocular pressure, or life-table estimates of the probability of successful treatment.

Clinical Trials as Topic↗
PubMed1980

Tracheal bronchus with regional ventilation and perfusion abnormalities.

Tracheal bronchus is an uncommon anomaly of the tracheobronchial tree. In the case presented, clinical and pathophysiologic abnormalities were associated with this anomaly. The tracheal bronchus supplied the right upper lobe of the lung. The bronchus intermedius arose directly from the trachea in place of the right main bronchus. It was accompanied by marked regional changes in ventilation and perfusion. We discuss the clinical significance of this unusual anomaly.

Aged↗
PubMed1978

Noncardiogenic pulmonary edema following blood transfusion.

Noncardiogenic pulmonary edema and acute respiratory failure were found to develop after blood transfusion. Pulmonary antiographic studies and hemodynamic measurements were performed in the presence of pulmonary edema. Normal wedge pressure was observed at the time of angiographic studies, and contrast material appeared to extravasate across the alveolocapillary membrane into the alveoli. The mechanisms of acute injury to the alveolocapillary membranes and of pulmonary edema secondary to reactions to transfusion are discussed.

Adult↗