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Biomedical subjects

J Houck

Publications and source records attributed to J Houck.

16 recordsLinked to original sources
PubMed2001

Giving way event during a combined stepping and crossover cutting task in an individual with anterior cruciate ligament deficiency.

STUDY DESIGN: Case study. OBJECTIVE: To compare knee kinematics and moments of nongiving way trials to a giving way trial during a combined stepping and crossover cutting activity. BACKGROUND: The knee kinematics and moments associated with giving way episodes suggest motor control strategies that lead to instability and recovery of stability during movement. METHODS AND MEASURES: A 27-year-old woman with anterior cruciate ligament deficiency reported giving way while performing a combined stepping and crossover cutting activity. A motion analysis system recorded motion of the pelvis, femur, tibia, and foot using 3 infrared emitting diodes placed on each segment at 60 Hz. Force plate recordings at 300 Hz were combined with limb inertial properties and position data to estimate net knee joint moments. The stance time, foot progression angle, and cutting angle were also included to evaluate performance between trials. RESULTS: Knee internal rotation during the giving way trial increased 3.2 degrees at 54% of stance relative to the nongiving way trials. Knee flexion during the giving way trial increased to 33.1 degrees at 66% of stance, and the knee moment switched from a nominal flexor moment to a knee extensor moment at 64% of stance. The knee abductor moment and external rotation moment during the giving way trial deviated in early stance. CONCLUSIONS: The observed response to the giving way event suggests that increasing knee flexion may enhance knee stability for this subject. The transverse and frontal plane moments appear important in contributing to the giving way event. Further research that assists clinicians in understanding how interventions can impact control of movements in these planes is necessary.

Adaptation, Physiological↗
PubMed2000

The genome sequence of Drosophila melanogaster.

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

Animals↗
PubMed1998

Evaluation of locus heterogeneity and EXT1 mutations in 34 families with hereditary multiple exostoses.

Hereditary multiple exostoses (EXT) is an autosomal dominant disorder characterized by growth of benign bone tumors. Three chromosomal loci have been implicated in this genetically heterogeneous disease: EXT1 at 8q24, EXT2 at 11p13, and EXT3 on 19p. EXT1 and EXT2 were recently cloned. We evaluated 34 families with EXT to estimate the proportion of disease attributable to EXT1, EXT2, and EXT3 and to investigate the spectrum of EXT1 mutations. Linkage analyses combined with heterogeneity testing provides strong evidence in favor of linkage of disease to both chromosomes 8 and 11, but does not support evidence of linkage to chromosome 19 in this data set. The 11 EXT1 exons were PCR-amplified and sequenced in all 11 isolated cases and in 20 of the 23 familial cases. Twelve different novel EXT1 mutations were detected, including 5 frame-shift deletions or insertions, 1 codon deletion, and 6 single base-pair substitutions distributed across 8 of the exons. Only 2 of the mutations were detected in more than one family. Three mutations affect sites in which alterations were previously reported. Nonchain-terminating missense mutations were identified in codons 280 and 340, both coding for conserved arginine residues. These residues may be crucial to the function of this protein. Although the prevalence of EXT has been estimated to be approximately 1/50,000 individuals, the disease has been reported to occur much more frequently in the Chamorro natives on Guam. Our detection of an EXT1 mutation in one Chamorro subject will allow investigation of a possible founder effect in this population. Combined mutational and heterogeneity analyses in this set of families with multiple exostoses suggest that 66% of our total sample, including 45% of isolated and 77% of familial cases, are attributable to abnormalities in EXT1.

Chromosomes, Human, Pair 11↗
PubMed1994

Survival and functional outcome after single and bilateral lung transplantation. Loyola Lung Transplant Team.

BACKGROUND: The experience at Loyola University Chicago was retrospectively reviewed to evaluate survival and functional outcome after single lung transplantation (SLT) and bilateral lung transplantation (BLT). METHODS: Ninety patients underwent lung transplantation at Loyola University Chicago between April 1990 and December 1993. Mean age was 45 years (range, 13 to 66 years). Fifty percent were male. Pre-lung transplant pulmonary diseases were as follows: emphysema and/or chronic obstructive pulmonary disease in 43 patients, pulmonary fibrosis in 13, cystic fibrosis in 14, pulmonary hypertension in eight, repeated transplantation for obliterative bronchiolitis in four, bronchiectasis in two, bronchoalveolar cell carcinoma in two, sarcoidosis in one, primary obliterative bronchiolitis in one, histiocytosis X in one, and lymphangiomyomatosis in one. Fifty-seven patients underwent SLT, and 33 had BLT. Maintenance immunosuppression medications consisted of cyclosporine, azathioprine, and prednisone. RESULTS: Perioperative complications were as follows: seven of 33 patients bled after BLT, and two of 57 bled after SLT. Bronchial complications were found in six of 66 (9%) BLT anastomoses and eight of 57 (14%) SLT anastomoses. Nine operative deaths occurred in SLT patients: six from allograft failure, one from infection, one from intrapulmonary hemorrhage, and one from bronchial dehiscence. Only two patients died in the perioperative period after BLT and that was of infection. Three late deaths occurred after BLT, all as a result of infection; 13 recipients died late after SLT: five of infection, four patients from lymphoma, two of pancreatitis, one of tension pneumothorax, and one of pulmonary embolism. For the entire patient population the actuarial 1- and 2-year survival rates were 72% and 68%, respectively. One-year survival rates were significantly better for patients undergoing lung transplantation for obstructive and nonrestrictive lung diseases than those of patients undergoing lung transplantation for vascular or restrictive pulmonary disease. Recipients of BLT had a trend toward better survival than recipients of SLT. Lung function 6 months after transplantation measured by forced expiratory volume in 1 second was significantly better in BLT than SLT, 71% of predicted versus 54%. CONCLUSIONS: Patients who undergo BLT have significantly better postoperative pulmonary function than those who undergo SLT. On the basis of the study there was a trend toward better survival with BLT.

Adolescent↗
PubMed1991

Technique and pitfalls of retrograde continuous warm blood cardioplegia.

The recent development of normothermic myocardial preservation and systemic perfusion during bypass has questioned the fundamental need for hypothermia during cardiac operations. The antegrade technique of almost continuous perfusion by the aortic root and vein grafts has been supplemented by continuous normothermic blood cardioplegia through the coronary sinus. Recently, great interest has been shown in this technique. It is important to describe the method in detail along with its potential shortcomings and dangers. This communication describes the technical details, pitfalls, and shortcomings of retrograde continuous warm blood cardioplegia.

Blood↗
PubMed1991

HLA antigens influence resistance to lung carcinoma.

The concept of genetic factors playing a role in the pathogenesis of lung cancer has gained increased attention. The present study was undertaken to reexamine the question of HLA antigen association with carcinoma of the lung. In a study of 90 patients, a significant association occurred between HLA-DR7 and resistance to lung cancer, after accounting for smoking status and sex. HLA class I antigens were also implicated. These results suggest that major histocompatibility complex loci affect carcinoma of the lung.

Carcinoma↗
PubMed1988

Airway obstruction due to lymphoma of the larynx and trachea.

Involvement of the larynx and trachea by lymphoma is an uncommon problem that can cause life-threatening airway obstruction. High grade obstruction, involvement of the soft tissue of the neck, and tracheal deviation can make intubation and tracheotomy hazardous, if not impossible. Tracheotomy can be ineffective with obstruction of the distal trachea. The clinical presentation and treatment of eight patients with lymphoma involving the larynx or trachea are presented with emphasis on airway management. Dramatic tumor response with relief of airway symptoms was achieved with a regimen of radiotherapy, chemotherapy, corticosteroids, helium-oxygen mixtures, humidity, and intensive care unit monitoring. Direct airway intervention, including tracheotomy, was usually successfully and safely avoided.

Adult↗
PubMed1987

Computer analysis of portal hemodynamics after small-diameter portacaval H-grafts: the theoretical basis for partial shunting.

We have previously reported on the clinical results of partial shunting using small-diameter portacaval H-grafts. In this study, we defined the theoretical basis for partial shunting using the Wheatstone bridge model of the splanchnic circulation. The model was modified to include a variable resistance for a portacaval shunt and was programmed as a computer simulation. We calculated portal flow as a function of shunt resistance to determine the resistance necessary to maintain prograde portal flow in patients with portal hypertension. The resistance of 8- and 10-mm portacaval H-grafts, as positioned clinically, was determined using a laboratory apparatus. The experimentally derived values for resistance were inserted into the graph of portal flow predicted by the computer program. Portacaval H-grafts 8 mm in diameter should produce prograde portal flow, 10-mm H-grafts should be borderline, and shunts larger than 10 mm should routinely result in reversed flow. These predictions were confirmed by clinical observations in 29 patients undergoing portacaval H-grafts.

Computer Simulation↗
PubMed1987

Single session treatment for bleeding hemorrhoids.

Fifty consecutive outpatients with bleeding internal hemorrhoids were prospectively treated with a single application of rubber band ligation or infrared coagulation. Complete follow-up observation was obtained in 48 patients (23 underwent rubber band ligation and 25 underwent infrared coagulation). At one month after treatment, 22 patients who underwent rubber band ligation and 16 who underwent infrared coagulation, were symptomatically improved (p less than 0.05). At six months, 15 patients who had undergone rubber band ligation and ten who had infrared coagulation treatment, remained improved (p less than 0.05). There was no statistical difference in the discomfort experienced by either group during or after the procedure as determined by a self-assessment scale. Two patients who underwent rubber band ligation experienced complications--a thrombosed external hemorrhoid developed in one patient and another had delayed rectal bleeding. Although associated with occasional complications after treatment, rubber band ligation is more effective than in infrared coagulation for single session treatment of bleeding internal hemorrhoids.

Ambulatory Surgical Procedures↗
PubMedDate not supplied

Optimal size matching in single lung transplantation.

BACKGROUND: Single lung transplantation for patients with end-stage obstructive lung disease has been highly effective in providing symptomatic relief, and it has been performed at a much increased frequency since 1983. However, there still lacks a convincing study showing the effect of size match and other preoperative variables in predicting functional outcome of patients after transplantation. METHODS: We evaluated 23 single lung transplantations performed for obstructive lung disease over a 34-month period. Multiple physiologic variables and size match criteria were evaluated for their contribution in determining the postoperative forced expiratory volume in 1 second at 3 months after transplantation. RESULTS: The size match ratio that was based on inframammary chest wall circumference was the most useful criterion to adopt, and the optimal donor/recipient size match ratio was 0.89. Furthermore, forced expiratory volume in 1 second at 3 months after transplantation could be predicted with a simple mathematical model that was based on the size match ratio and the recipient's calculated vital capacity of the transplanted hemithorax. CONCLUSIONS: This model could be applied in a clinical setting to maximize functional outcome of the recipients undergoing single lung transplantation.

Adult↗
PubMedDate not supplied

Incidence of phrenic neuropathy after isolated lung transplantation. The Loyola University Lung Transplant Group.

BACKGROUND: Isolated lung transplantation is a viable therapeutic option for many patients with end-stage pulmonary disease. Other intrathoracic surgical procedures have a well documented incidence of phrenic nerve dysfunction, although the incidence after lung transplantation has not been studied. METHODS: Thirty-one patients who underwent lung transplantation were evaluated for evidence of phrenic nerve dysfunction and subsequent recovery. Risk factors contributing to the incidence of injury were examined. Phrenic nerve injury was defined by two separate diagnostic tests (Transcutaneous Phrenic Nerve Conduction Studies and Fluoroscopic evaluation of diaphragmatic movement) used in combination. RESULTS: Of the 27 patients who were completely evaluated after the operation, eight had defining criteria for nerve injury--an incidence of 29.6%. Of those affected, the majority of injuries (89%) resulted in complete paralysis of the affected hemidiaphragm. The highest incidence of injury occurred in patients who underwent bilateral single lung transplantation (41%), with the right phrenic nerve being injured most often (78%). Fortunately, no significant postoperative morbidity was attributable to the occurrence of phrenic nerve injury when compared with those patients who did not sustain injury. CONCLUSIONS: The analysis of possible risk factors resulted in the hypothesis that the likely mechanism of injury in these patients was due to stretching or direct instrumentation of the nerve, and thus measures should be instituted to minimize the possibility of injury.

Adult↗