Search PubMed⌕ Search

Biomedical subjects

R S Smith

Publications and source records attributed to R S Smith.

At least 109 records · Page 6Linked to original sources
PubMed1994

Structure-function relationships for polysaccharide-induced intra-abdominal abscesses.

We have previously shown that in an animal model of sepsis positively and negatively charged groups on polysaccharide A of Bacteroides fragilis are essential for the induction of intra-abdominal abscess formation (A. O. Tzianabos, A. B. Onderdonk, B. Rosner, R. L. Cisneros, and D. L. Kasper, Science 262:416-419, 1993). By introducing chemical modifications into the structures of B. fragilis polysaccharide B as well as other abscess-inducing bacterial polysaccharides, we observed the following. (i) The presence of a nonacetylated free amino group on these polysaccharides appears to be required for abscess induction. (ii) No specific type of negatively charged group is essential to abscess induction by these polysaccharides. (iii) The density of free amino groups on these polysaccharides influences this pathobiologic host response.

Abdomen↗
PubMed1994

Definition of a nonlinear conformational epitope for the apolipoprotein B-100-specific monoclonal antibody, MB47.

The apolipoprotein (apo) B-100-specific monoclonal antibody MB47 has been widely used in lipoprotein metabolism and atherosclerosis research. When bound to apoB-100 on low density lipoproteins (LDL), antibody MB47 completely blocks the binding of LDL to the LDL receptor. The epitope for antibody MB47 has previously been mapped to the vicinity of apoB-100 amino acid (aa) residue 3500. To map the epitope for antibody MB47 more precisely, we used recombinant bacterial fusion proteins. Antibody MB47 bound strongly to a fusion protein containing apoB-100 aa 3214-3728, but no specific binding was observed to fusion proteins containing aa 3214-3351, 3214-3506, 3351-3506, or a fusion protein containing aa 3214-3351 and 3506-3728. Although antibody MB47 did not bind to aa 3214-3506, it did bind to aa 3214-3510. Further fusion protein studies revealed that antibody MB47 bound to aa 3429-3510, but bound only very weakly to aa 3453-3510, indicating that aa 3429-3453 constitute an important part of the MB47 epitope. Subsequent fusion protein studies revealed that MB47 bound much more strongly to aa 3429-3523, 3429-3544, 3429-3565, and 3429-3590 than to aa 3429-3510. Thus, aa 3507-3523 also constitute an important part of the MB47 epitope. In summary, the fusion protein data indicated that two nonlinear domains of apoB-100 separated by approximately 53 aa (the 25 residues from aa 3429 to 3453 and the 17 residues from aa 3507 to 3523) form key parts of the MB47 epitope.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1994

Triage of American combat casualties: the need for change.

United States military medical planning must reevaluate the practices of combat casualty resuscitation, transportation, and triage to secondary echelon care. Analysis of the experiences of other medical commands, such as that of the Israeli Defense Force, offers insight into improvements in equipment and training that are achievable with minimal cost. Training programs must involve formal instruction in Advanced Trauma Life Support for the combat corpsman, and ongoing experience in trauma surgery for personnel who are placed in the role of military surgeons. Today in military medicine there exists a major deficiency of expertise in trauma care, arising through a near total lack of involvement in active trauma surgery on the part of military medical training facilities. Civilian trauma centers offer an abundance of opportunity for military-like casualty management, and successful efforts at our command have integrated active duty personnel into this experience.

Humans↗
PubMed1994

Microphthalmia and associated abnormalities in inbred black mice.

Although microphthalmia and anophthalmia develop in many animals, they are a consistent and frequent finding in inbred and congenic strains of C57BL mice. Many investigators fail to take account of an incidence that may be as high as 12%, and this may lead to misinterpretation of experimental results. Further confusion may arise from the higher frequency in female mice and from the effects of various environmental and breeding conditions. In anophthalmic and severely microphthalmic mice, there is faulty tear drainage function, which often leads to ocular infections. It should be emphasized that these infections are a function of the ocular malformations arising from the genetic characteristics of C57BL strains and do not represent a failure in proper animal husbandry practices. Histologic studies confirm the consistency and the variability of the ocular findings in these strains. The eye abnormalities may be unilateral or bilateral and, for unexplained reasons, have a strong predilection for the right eye. Microphthalmia may be subtle and clinical anophthalmia may actually represent severe microphthalmia. Accordingly, any conclusions for these inbred strains regarding the eyes should be accompanied by careful microscopic examination of all animals. The most common findings include central corneal opacities, iridocorneal and corneal-lenticular adhesions, abnormal formation of the iris and ciliary body, cataracts, extrusion of lens cortical material with dispersion throughout the eye, failure of vitreous development, and retinal folding. The incidence of all of these findings is increased by exposure to alcohol at critical stages of embryogenesis. Mesodermal dysgenesis of the anterior segment in human eyes mimics the findings seen in inbred C57BL strains of mice, although severe microphthalmia or anophthalmia is less commonly seen. These similar human findings have been associated with a complexity of chromosomal abnormalities and inheritance patterns. Development of the fetal alcohol syndrome in human eyes also provides a phenocopy of the anterior segment abnormalities of mice and of the human familial syndromes. The events, which result in abnormalities in mice and humans, all center around the time in embryogenesis when the optic cup and lens vesicle are developing. In all instances, the lens tends to be smaller than normal and may be displaced in position with relation to the optic cup. This relationship between lens and optic cup is critical in normal development of other ocular structures, including the iris, ciliary body, vitreous, and retina.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Successful laparoscopic splenorrhaphy using absorbable mesh for grade III splenic injury: report of a case.

We report herein on successfully performing a laparoscopic mesh splenorrhaphy in addition to blood salvage on a patient with a grade III splenic injury from blunt abdominal trauma. Given the lower success rates for nonoperative observation in grade III splenic trauma, we believe laparoscopic evaluation of splenic injury may offer an improved assessment over computed tomography (CT) scanning by localizing and quantitating the source of blood loss while at the same time enabling the surgeon to perform laparoscopically assisted blood salvage, autotransfusion, and laparoscopic repair. These advantages in diagnosis and therapy warrant further investigation into the role of laparoscopy in the evaluation and treatment of splenic trauma in selected stable patients.

Absorption↗
PubMed1994

Limited utility of emergency department thoracotomy.

To assess the therapeutic role and cost effectiveness of resuscitative thoracotomy in an urban trauma center, a retrospective review of thoracotomies (n = 273) performed in a trauma unit between 1986 and 1992 was undertaken. A total of 252 thoracotomies were performed for penetrating injuries (92%), and 21 (8%) were performed for blunt trauma. Ten neurologically intact survivors (3.7%) were identified. Mechanisms of injury in survivors were stab wound (n = 6) and gunshot wound (n = 4). There were no neurologically intact survivors when resuscitative thoracotomy was done for blunt trauma. All survivors sustained penetrating truncal injuries; isolated thoracic injuries existed in six patients, while four patients presented with both thoracic and abdominal wounds. All survivors had signs of life either in the field or in the trauma unit. Of the 242 non-survivors who had sustained penetrating trauma, only 49 had signs of life either in the field or upon arrival at the trauma unit. In this group, survival was 17 per cent. Revised Trauma Scores, calculated in the trauma unit, failed to differentiate between survivors and nonsurvivors. In 1992, the average hospital charge for resuscitative thoracotomy was $3413 per patient. Total charges during the study period for resuscitative thoracotomy were approximately $932,000. This represents an expenditure of $93,000 per successful thoracotomy. If thoracotomy was limited to patients sustaining penetrating trauma who demonstrated signs of life, total charges would be approximately $201,367, representing an expenditure of $20,137 per successful thoracotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1994

Cardiac injuries: analysis of an unselected series of 251 cases.

Retrospective analysis was performed on the medical records of 251 patients treated for cardiac injuries at Highland General Hospital trauma facility in Alameda County, California, to identify factors that contribute to patient survival and predict death. Thirty-six patients (14%) had blunt injuries, 153 patients (61%) had gunshot wounds (GSW), and 62 patients (25%) had stab wounds. The overall survival rate was 18.7%, GSW survival was 6.5%, stab wound survival was 37.1%, and blunt injury survival was 40%. Patients who arrived with some vital signs had 62.2% survival and patients who arrived with absent vital signs had < 1% survival. Stepwise multiple logistic regression analysis revealed that for patients with absent vital signs the only significant predictor of outcome was GSW as the mechanism of injury and for patients with vital signs the ISS and the presence of combined right and left heart injuries were significant independent predictors of outcome. We conclude that the routine and aggressive use of emergency room thoracotomy for patients with penetrating cardiac injury must be re-examined.

Adolescent↗
PubMed1994

Gasless laparoscopy using a planar lifting technique.

In clinical use, the mechanical lifting technique has demonstrated the ability to displace the abdominal wall and create a useful cavity for visualization and surgical manipulation. By forming a planar ceiling, as opposed to the domed ceiling of conventional pneumoperitoneum, the abdominal organs are brought into closer proximity of the surgeon. Instrument length may be shortened, imparting greater surgical control. Without the necessity for gas sealing, entry portals are simplified. Conventional instruments (right angle clamps) may be introduced through the fan retractor insertion sites or by way of separate stab incisions. The planar lifting technique has the potential for simplifying laparoscopy and restoring instrument control to the operating surgeon.

Abdominal Muscles↗
PubMed1994

Is needle-directed breast biopsy overused?

We undertook this study of needle-localized breast biopsy--a frequently done surgical procedure--to examine current practice patterns and to determine if the technique is overused in any group of patients. From a retrospective review of medical records of all patients who had needle-localized breast biopsy at a teaching hospital between June 1, 1988, and October 31, 1990, we found that a total of 125 were done: 24 biopsy specimens showed malignancy (19%). Mammographic indications for biopsy were microcalcification (n = 62, or 50%), mass or density (n = 60, or 48%) and mass and calcifications (n = 3, or 2%). Indications for biopsy in patients with cancer were microcalcification (14 patients) and mass or density (10 patients). The incidence of malignancy increased with age. In patients younger than 40 years, no biopsy showed malignancy. Only 2 of 30 biopsies done in patients younger than 50 showed cancer (7%). Breast cancer was most frequently discovered in patients in the seventh and eighth decades of life, and this group accounted for 75% of "positive" biopsies. Needle-localized breast biopsy is a useful technique in the early diagnosis of breast cancer. Although indications for the procedure should remain liberal, in women younger than 50, the percentage of biopsies that reveal malignancy is low.

Adult↗
PubMed1993

Persistence of axonal transport in isolated axons of the mouse.

We have examined the hypothesis, for the case of mouse axons, that isolating an axon from its cell body will lead to a rapid failure of fast axonal transport as anterogradely moving organelles vacate the axon in a proximo-distal direction, and retrogradely moving organelles vacate it in the opposite direction. We used CD1 and BALB/c mice and the Wallerian degeneration-resistant mutant C57BL/Ola. Sciatic nerves were cut high in the thigh; at various times up to 8 days later nerves were removed from the animal and individual myelinated axons from the segment distal to the cut were examined by video light microscopy to detect rapid organelle transport. Bidirectional fast organelle transport did decrease in amount with time but not nearly as rapidly as predicted, and anterograde and retrograde organelle velocities remained normal through time. In the C57BL/Ola mouse some structurally preserved axons contained organelles that transported at normal velocities in the anterograde and retrograde directions for as long as 8 days after axotomy. To test one of the possible origins of transported organelles in long-surviving axons we examined organelle transport very close to narrow lesions in axons bathed in a medium compatible with intracellular function. No organelles crossed the lesion but bidirectional organelle transport took place proximal and distal to the lesion; the amounts were compatible with the interpretation that approximately 30% of organelles reversed transport direction on either side of the lesion. We propose that at least some of the organelles that undergo persistent transport in axons isolated from their cell bodies shuttle back and forth between the ends of the isolated segment.

Animals↗
PubMed1993

Gasless laparoscopy and conventional instruments. The next phase of minimally invasive surgery.

OBJECTIVE: To assess the capability of a retractor system that permits laparoscopic surgery without pneumoperitoneum and to determine if the system facilitates the use of conventional surgical instruments during minimally invasive surgery. DESIGN: Prospective evaluation and data collection with review. SETTING: University-affiliated county hospital. PATIENTS: Twenty-nine male and 29 female subjects evaluated prospectively via 27 trauma-related and 31 elective procedures. METHODS: Fifty-eight laparoscopic procedures were performed between July 1992 and February 1993 with a system consisting of an intra-abdominal fan retractor and an electrically powered mechanical arm using conventional surgical and laparoscopic instruments. RESULTS: Gasless laparoscopy was used in the evaluation of 27 patients with abdominal trauma (11 gunshot wounds, 11 stab wounds, and five blunt injuries). The need for celiotomy was obviated in 20 (74%) of 27 cases. Three enterotomies, two diaphragmatic lacerations, and one gastric perforation were repaired with conventional instruments. Gasless laparoscopic techniques were also used in cholecystectomy (n = 26), diagnostic laparoscopy (n = 3), and appendectomy (n = 2). Exposure similar to that obtained by pneumoperitoneum was obtained in 30 (97%) of 31 cases. One major (trocar tip enterotomy) and two superficial wound infections occurred in this group. The ability to use conventional surgical instruments was advantageous in several cases. CONCLUSIONS: Comparable exposure was achieved in this cohort of patients with gasless laparoscopy. The use of conventional surgical instruments provides an advantage with this technique. Further improvements in abdominal wall lift systems and modification of existing surgical instruments may expand the role of gasless laparoscopy.

Abdominal Injuries↗
PubMed1993

The success of duplex ultrasonographic scanning in diagnosis of extremity vascular proximity trauma.

OBJECTIVE: To determine if duplex ultrasonographic scanning is diagnostically equivalent to arteriography and/or operative exploration in the diagnosis of extremity vascular proximity trauma. DESIGN: A prospective evaluation comparing duplex scanning with arteriography or operative exploration in 50 patients. Subsequently, duplex scanning was used alone for 175 extremity vascular proximity injuries, with other diagnostic methods used when injury was indicated on the duplex scan. SETTING: A busy urban trauma center. PATIENTS: Consecutive sample of 200 patients with 225 extremity injuries. SELECTION CRITERIA: Vascular proximity injury or diminished strength of the extremity pulse. MAIN OUTCOME MEASURES: The presence or absence of vascular proximity injury confirmed on angiography and/or operative exploration. RESULTS: Duplex scanning had 100% sensitivity and 100% specificity compared with arteriography and/or operative exploration in the first 50 cases. In the remaining 175 cases of extremity trauma, vascular injuries were diagnosed with duplex scanning alone. Duplex scanning detected 18 injuries, 17 of which were confirmed by correlation with arteriograms and/or operative exploration. One false-positive result--spasm of the superficial femoral artery--was found on arteriography. Seven unsuspected venous injuries were also diagnosed. CONCLUSIONS: Duplex scanning is a noninvasive, safe, effective method for the initial evaluation of potential extremity vascular proximity injury. It has replaced arteriography in the initial diagnosis of extremity vascular proximity trauma by our trauma service.

Angiography↗
PubMed1993

Relationship of apolipoprotein E phenotypes to hypocholesterolemia.

PURPOSE: Persons with total cholesterol (TC) levels less than 130 mg/dL (less than 3.26 mmol/L) make up less than 1% of a healthy population. Causes of hypocholesterolemia include a diet very low in cholesterol and saturated fat, disease, genetic factors (including low apolipoprotein B-100 [apo B-100] and the apo E allele), and drug therapy. The purpose of this study was to determine the causes of hypocholesterolemia in a healthy Kaiser Foundation Health Plan (KFHP) population. PATIENTS AND METHODS: We conducted a dietary and health survey of 201 healthy hypocholesterolemic adults (range: 2.04 to 3.88 mmol/L [79 to 150 mg/dL]) and 200 matched control subjects with TC levels in the middle quintile of the population (range: 5.0 to 5.61 mmol/L [194 to 217 mg/dL]) who had routine health screening from 1983 through 1985. We did apo E phenotyping studies and lipid and apo A-1 and B-100 measurements in a subgroup of 45 hypocholesterolemic subjects (mean TC level: 3.26 mmol/L [126 mg/dL]) and in a comparison group of 49 unmatched volunteers (mean TC level: 5.04 +/- 0.75 mmol/L [195 +/- 29 mg/dL]). RESULTS: We found no differences in dietary intake or clinically significant medical illness between hypocholesterolemic and control subjects. In the hypocholesterolemic subgroup, we found an increased frequency of the apo E2 allele (epsilon 2) and a decreased frequency of the apo E4 allele (epsilon 4); the frequencies of the epsilon 2, epsilon 3, and epsilon 4 alleles were 33.3%, 63.3%, and 3.3%, respectively. The corresponding apo E allele frequencies in the comparison subgroup were 8.2%, 73.5%, and 18.4%, similar to those previously reported for the general population and significantly different from those found in the hypocholesterolemic subgroup (p < 0.0001). One hypocholesterolemic subject (a 46th patient) had a mutation in the apo B gene that resulted in the synthesis of a truncated species of apo B (apo B-46). CONCLUSION: Our study indicates that hypocholesterolemia in our KFHP urban population is usually not caused by diet or disease. Biochemical factors, including the increased frequency of the apo E-2 phenotype and the decreased frequency of the apo E-4 phenotype, are more important.

Adult↗
PubMed1993

Ultrasonographic prediction of neonatal survival in extremely low-birth-weight infants.

OBJECTIVE: Our purpose was to improve the accuracy of prenatal prognostication by directly correlating obstetric ultrasonographic measurements with neonatal survival. STUDY DESIGN: We studied 130 singleton live-born infants with birth weights between 500 and 1000 gm and who underwent complete ultrasonographic examinations within 3 days of delivery. Ultrasonographic measurements were evaluated as screening tests for neonatal survival by means of receiver-operator characteristic curves and compared with birth weight and pediatric assessment of gestational age. RESULTS: Eighty infants survived, and 50 died. Visual inspection of the receiver-operator characteristic curves indicated that biparietal diameter was the best predictor of survival. While correctly identifying all survivors, biparietal diameter predicted nonsurvivors better (p < 0.0001) than did actual birth weight or any other variable. CONCLUSION: Our findings indicate that using biparietal diameter to determine neonatal prognosis is significantly more reliable than the current practice of using estimated fetal weight. We speculate that biparietal diameter may reflect maturity more accurately because it is less subject to variation in growth.

Biometry↗
PubMed1993

Preliminary report on videothoracoscopy in the evaluation and treatment of thoracic injury.

A prospective trial of videothoracoscopy was conducted at an urban trauma center between February 1992 and February 1993 to determine the efficiency of this less invasive method of evaluation and treatment. Twenty-four consecutive patients with chest trauma (penetrating, n = 22; blunt, n = 2) were examined thoracoscopically for clotted hemothorax that otherwise would have been treated with thoracotomy (n = 9), suspected diaphragmatic injury (n = 10), and continued bleeding (n = 5). To ensure maximal exposure, general anesthesia with a double-lumen endotracheal tube was used in each patient. Clotted hemothorax was successfully evacuated in eight of nine patients (89%). Diaphragmatic laceration was suspected in 10 patients (2 abnormal chest radiographs, 8 proximity penetrating wounds) and confirmed thoracoscopically in 5. In four patients, diaphragmatic lacerations were successfully repaired with thoracoscopic techniques. Five patients underwent thoracoscopy for continued hemorrhage (greater than 1,500 mL per 24 hours) after tube thoracostomy. Intercostal artery injury was confirmed in all patients, and diathermy provided hemostasis in three patients without thoracotomy. No complications occurred. These data suggest the following: (1) Videothoracoscopy is an accurate, safe, and minimally invasive method for the assessment of diaphragmatic injuries, control of continued chest wall bleeding, and early evacuation of clotted hemothorax. (2) This technique should be used more frequently in patients with thoracic trauma. (3) Technical advances may expand the therapeutic role of thoracoscopy.

Adolescent↗