Search PubMed⌕ Search

Biomedical subjects

F A Mann

Publications and source records attributed to F A Mann.

At least 55 records · Page 3Linked to original sources
PubMed1998

Imaging of acute thoracic aortic injury due to blunt trauma: a review.

Much recent work on the use of computed tomography (CT) and transesophageal echocardiography in screening for and facilitating the diagnosis of acute thoracic aortic injury in the patient with blunt chest trauma has shown favorable results. This has led some physicians to question whether conventional thoracic aortography is still the reference standard. The purpose of this review article is to summarize the epidemiology and pathophysiology of acute thoracic aortic injury, the current status of the individual imaging modalities in use, and the surgeon's perspective. Despite a burgeoning literature and a confounding array of clinical and imaging advances, timely diagnosis of acute thoracic aortic injury remains a challenge. To overcome this problem, some trauma centers have used CT, transesophageal echocardiography, or both, in their diagnostic algorithm for acute thoracic aortic injury. These diagnostic algorithms are individually tailored by each institution and are still under investigation; therefore, no definite conclusions can be reached.

Acute Disease↗
PubMed1997

Diagnosis of injuries after stab wounds to the back and flank.

BACKGROUND: Historically, patients with deep posterior wounds underwent a formal celiotomy to rule out injury. Currently, we use a policy of selective management. The purpose of this review is to evaluate our experience with selective management to identify potential areas of further improvement. METHODS AND RESULTS: This study includes 203 patients over a 10-year period. By changing from a policy of mandatory exploration to selective management the total celiotomy rate decreased from 100 to 24% and the therapeutic celiotomy rate increased from 15 to 80%. CONCLUSIONS: In stable patients, a diagnostic peritoneal lavage should be performed as the initial diagnostic study. When diagnostic peritoneal lavage is negative, triple contrast computed tomography should be performed to evaluate the remaining retroperitoneal structures. Any suggestion of pericolonic extravasation of contrast or air, edema, or hemorrhage must be interpreted as a positive study and prompt consideration for operative exploration.

Abdominal Injuries↗
PubMed1997

Scaphopisocapitate alignment: criterion to establish a neutral lateral view of the wrist.

PURPOSE: To determine whether a "true" neutral lateral view of the wrist is necessary for accurate capitolunate angle measurement, to compare two standards of diagnostic adequacy for neutral lateral wrist views (distal radioulnar overlap [RUO] and scaphopisocapitate [SPC] relationship), and to confirm positional reproducibility and measurement precision of the SPC criterion. MATERIALS AND METHODS: Capitolunate angles were measured on neutral lateral and supine pisotriquetral views of 10 normal wrists. Two hundred neutral lateral wrist views were classified by each standard (RUO and SPC) as excellent, acceptable, or unacceptable. In two subgroups, capitolunate angles were measured on the lateral views to determine SPC practicality and sensitivity. RESULTS: Compared with neutral lateral positioning, supinated off-lateral views showed an apparent increase in lunate dorsiflexion of up to 30 degrees. Diagnostically unacceptable, excellent, and acceptable pronosupination was present on 118, 22, and 60 of 200 views by using the RUO criterion and on 40, 79, and 81 of 200 views by using the SPC criterion, respectively. The capitolunate angle did not show a significant difference between each of the two subgroups (P > .05). CONCLUSION: A true neutral lateral view of the wrist is necessary for accurate measurement of the capitolunate angle on the basis of a comparison with off-lateral views. SPC relationship provides a diagnostically reproducible standard for a neutral lateral wrist view and should reduce the need for repeat lateral radiographs.

Adult↗
PubMed1997

MR imaging of clinically suspected scaphoid fractures.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of MR imaging in revealing occult fractures in patients with clinically suspected acute scaphoid fractures who have normal or equivocal findings on radiographs. SUBJECTS AND METHODS: Thirty-six patients underwent MR imaging within 7 days of wrist injury. All had physical findings suggestive of scaphoid fracture. Coronal T1-weighted, short inversion time inversion recovery, and either T2-weighted or proton density-weighted fast spin-echo sequences with fat suppression were used. Follow-up radiographs were obtained at least 2 weeks after MR imaging whenever possible. All imaging studies were reviewed by two musculoskeletal radiologists. RESULTS: MR imaging revealed 22 occult fractures in 20 patients. Thirteen of these 22 fractures were in the scaphoid bone, and nine were in the distal radius. On MR images, 16 patients had no evidence of fracture. Follow-up radiographs were available in 14 of the 20 patients who had occult fracture revealed by MR imaging. Eleven of the 13 occult fractures of the scaphoid bone were followed up (two were lost to follow-up), and 10 of the 11 showed signs of healing. Five of the nine lesions of the distal radius were followed up, and three of these showed evidence of healing fracture. Three patients without MR evidence of a fracture had follow-up radiographs that showed no fracture. Three patients had findings consistent with bone contusion on MR images; in two patients, the contusion was associated with other fractures, and in one patient, the contusion was isolated. CONCLUSION: MR imaging can reveal occult wrist fractures when findings on radiographs are normal or equivocal.

Adult↗
PubMed1996

Evaluation of cortical bone damage and axial holding power of nonthreaded and enhanced threaded pins placed with and without drilling of a pilot hole in femurs from canine cadavers.

OBJECTIVE: To evaluate the in vitro axial extraction forces necessary to remove pins and to evaluate mechanical trauma resulting from pin insertion, using various types of pins and insertion techniques. DESIGN: Prospective, controlled study. SUBJECTS: Femurs of cadavers of dogs. PROCEDURE: Pins were inserted as follows: 1 nonthreaded pin without drilling of a pilot hole, 1 enhanced threaded pin with drilling of a pilot hole, and 1 enhanced threaded pin without drilling of a pilot hole. After pin insertion, mechanical damage and proper pin insertion was determined by means of radiography. Axial extraction forces were determined for all pins, using a universal testing machine. Mechanical damage was evaluated in 12 additional femurs. After pin insertion, all pins were removed from the bone by use of a low-speed power drill. Samples were sectioned, processed, and evaluated by use of dissecting and scanning electron microscopy. RESULTS: Using radiography, a significant difference was detected in the number of periosteal trans-cortex fractures between the enhanced threaded and nonthreaded pins. Axial extraction force was not significantly different between the enhanced threaded pins, regardless of insertion technique; however, the axial extraction force was significantly greater for enhanced threaded pins, compared with that for nonthreaded pins. Microfractures only were detected on the periosteum of the trans-cortex of enhanced threaded pins by use of scanning electron microscopy. CLINICAL IMPLICATIONS: We cannot recommend a particular insertion technique to decrease mechanical trauma to the bone and to increase axial extraction force needed for removal of enhanced threaded pins from the femur of dogs.

Animals↗
PubMed1996

Radiographic recognition of the sacral alar slope for optimal placement of iliosacral screws: a cadaveric and clinical study.

Malpositioning of iliosacral screws happens more often when common variations in the morphology of the upper sacral segments are unrecognized. Radiological-anatomic correlations of sacral anatomy were studied in 10 fresh-frozen cadaveric pelvises without evidence of skeletal disease, obtained from six male and four female donors. Eighty consecutive patients with complicated pelvic fractures treated operatively by the same surgeon using percutaneously placed iliosacral screws were evaluated. Variations in the sacral alar anatomy and slope found in upper sacral segmentation anomalies are common. Surgically important and predictable abnormal morphological patterns can be easily identified using pelvic outlet and lateral sacral plain radiographs along with computed tomographic scans. On the true lateral projections, the iliac cortical density adjacent to the sacroiliac joint parallels the sacral alar slope and is almost always caudal and posterior to it; it delineates the anterior extent of the "safe zone" for iliosacral screw insertion. Thus, the lateral sacral image provides the surgeon with a better understanding of the sacral alar slope and can help prevent iliosacral screw placement errors. The lateral sacral image should always be used intraoperatively with the inlet and outlet images to guide iliosacral screw placement.

Adolescent↗
PubMed1996

Antigen-specific humoral immune responses to a hapten-carrier conjugate in SCID mice engrafted with bovine fetal hematopoietic tissues.

We describe the conditions necessary to reconstitute a bovine immune system in SCID mice that supports the generation of antigen-specific serum antibody responses to a hapten-carrier (DNP-KLH) conjugate. Sublethally irradiated SCID mice were engrafted with fetal bovine liver, lymph node, and thymus. Treatment groups were established in which human recombinant interleukin 7, autologous bovine bone marrow, and engraftment site (omentum or abdominal wall) were evaluated for their ability to enhance the reconstitution of the bovine immune system in SCID mice. Engrafted SCID mice were inoculated at approximately 6 and 12 weeks after engraftment with DNP-KLH. Vaccinated mice were evaluated by enzyme-linked immunosorbent assay for serum antibody specific for DNP-KLH and total concentrations of bovine serum immunoglobulin biweekly through 20 weeks after engraftment. The SCID mice with fetal tissues engrafted onto the abdominal wall from two different donors produced microgram quantities of bovine immunoglobulins and had >70% reconstitution rate. Administration of human interleukin 7 and/or fetal bovine bone marrow did not significantly increase the frequency of reconstitution. Subclass analysis of serum from mice receiving the abdominal implants suggested that class-switching occurred to a predominant non-IgM isotype response after the second inoculation. Pooled thymic and splenic cell populations obtained 20 weeks after engraftment from abdominally engrafted groups yielded 38 to 90% bovine cells, as determined by polymerase chain reaction in situ hybridization with bovine satellite DNA-specific primers. These results indicate that an antigen-specific bovine immune response can be generated in heterochimeric SCID-bo mice.

Animals↗
PubMed1996

Subchronic centrifugal mechanical assist in an unheparinized calf model.

The purpose of this study was to determine whether the major centrifugal pumps currently in use in the United States (Medtronic, BioMedicus BioPump and Carmeda-coated BioPump, Sarns 3M centrifugal pump, and St. Jude Medical Lifestream) could function as left mechanical assist devices in the subchronic (72 h) unheparinized calf model. Calves were instrumented for left atrial to aorta ex vivo assist, and the pump flow was set at 3.5 +/- 0.4 L/min. Two calves (Sarns 3M and St. Jude) survived 72 h of pumping without clinical complications. The other 2 calves died at 62 and 66 h (Medtronic BioPump and Carmeda-coated BioPump, respectively); both had pelvic limb paralysis. The seal of the Sarns 3M pump head ruptured after approximately 36 h of pumping and required replacement. On postmortem examination, pump-associated thromboembolic lesions were detected in 3 of the 4 calves in one or more of the following organs: kidneys, pancreas, abomasum, duodenum, ileum, spleen, and lumbar spinal cord. The calf with the Sarns 3M pump had no discernable lesions. Because of the clinical abnormalities and postmortem lesions in the unheparinized calf model, it was suggested that anticoagulation is necessary for conducting centrifugal mechanical assist studies in calves using presently available technology.

Analysis of Variance↗
PubMed1996

A calf model for left ventricular centrifugal mechanical assist.

The increased use of centrifugal mechanical assist (CMA) for treatment of refractory postcardiotomy cardiogenic shock highlights the need for experimental testing to improve clinical results. This report describes the preoperative conditioning, anesthetic and surgical technique, and postoperative management of a reliable calf model refined in this laboratory for in vivo subchronic (96 h) testing of CMA. Holstein bull calves (2 to 3 months old; mean body weight, 78 kg; n = 35) were instrumented for left ventricular CMA; 4 of these calves were sham-operated controls. Anesthetic recovery and postoperative restraint were accomplished in a specially designed crate to which each calf was preconditioned extensively. Younger calves were more readily conditioned and more tolerant of postoperative restraint than older calves. One calf died of ventricular fibrillation intraoperatively. One calf that had been heparinized developed uncontrollable hemothorax and died 12 h postoperatively. One calf prematurely dislodged his aortic cannula 15 h postoperatively and exsanguinated. Six calves developed pelvic limb paresis or paralysis because of lumbar spinal cord thromboembolism by 36 h postoperatively, and 3 of these calves were sacrificed by 42 h postoperatively. Fifteen calves required sedation in the first 12 h after the operation. Tachycardia associated with bottle feeding occurred in 15 calves. Second-degree atrioventricular block was noted frequently during deep relaxation. Postmortem examination demonstrated the absence of surgical wound and distant infection, security of cannulae in all but the calf that prematurely dislodged the aortic cannula, absence of thrombus formation at cannulation sites, and presence of thromboembolism in 51% of the calves. The incidence of thromboembolic lesions was not influenced by the need for chemical restraint, by the occurrence of feeding-associated tachycardia, or by the presence of atrioventricular block. There were no thromboembolic lesions in any of the sham-operated controls.

Anesthesia↗
PubMed1995

Indirect forces and patella fracture after anterior cruciate ligament reconstruction with the patellar ligament. Case report.

Patella fracture is either an infrequent or underreported complication after anterior cruciate ligament (ACL) reconstruction using a portion of the patellar ligament. Patella fracture pattern has been related to the mechanism of injury. Direct fractures resulting from impaction forces delivered to the patella are typically stellate or comminuted. Indirect fractures resulting from tensile stresses applied across the extensor mechanism typically are displaced transverse disruptions. After ACL reconstruction using a portion of the patellar ligament, Y-shaped stellate fractures can occur. Fracture pattern seems related to the time elapsed since the harvest; stellate fractures occur following stumbles or slips without direct injury early in the postoperative period while transverse fractures occur late. This article describes two cases of patella stellate fractures that occurred in patients who underwent ACL reconstruction using patellar graft.

Adult↗
PubMed1995

Androgen receptors in the pelvic diaphragm muscles of dogs with and without perineal hernia.

Levator ani and coccygeus muscle estrogen and androgen receptors were measured in 6, healthy, > or = 5-year-old, noncastrated, male Beagles (controls) and in 24 dogs with perineal hernia. Estrogen and androgen receptor analyses were performed on levator ani and coccygeus muscle specimens obtained from control dogs at the time of castration; contralateral levator ani and coccygeus muscle specimens were assayed 2 months after castration. During herniorrhaphy of dogs with perineal hernia, levator ani (non-castrated, n = 12; castrated, n = 7) and/or coccygeus (noncastrated, n = 5; castrated, n = 4) muscle biopsy specimens were obtained for estrogen and androgen receptor analyses. For estrogen and androgen receptor assays, each muscle biopsy specimen was homogenized in Tris-EDTA-glycerol buffer, and centrifuged at 30,000 x g; extracts were used for binding with ligands: [3H]methyltrienolone (3HR1881) for androgen receptors, and [3H]estradiol-17 beta for estrogen receptors. Extracts were incubated overnight at 0 to 4 C. Nonspecific binding was estimated, using 100-fold concentration of cold ligands. Bound and free hormones were separated, using hydroxylapatite batch assay. Receptor numbers for each tissue were calculated as femtomoles (fmol) per milligram of protein. Quantified data were compared between precastration and postcastration controls, using a paired t-test. One-way ANOVA and Bonferroni post-hoc test were used to compare values for precastration controls, postcastration controls, castrated dogs with perineal hernia, and noncastrated dogs with perineal hernia. Significance was set at P < 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Permanent urinary diversion in two Vietnamese pot-bellied pigs by extrapelvic urethral or urethropreputial anastomosis.

Permanent urinary diversion was performed in a Vietnamese pot-bellied pig to bypass apparent urethral obstruction at the level of the urethral recess and in a second pig to correct bleeding from perineal urethrostomy. In the first pig, extrapelvic anastomosis of the penile portion of the urethra to the pelvic portion of the urethra was performed. In the second pig, the penis was amputated and the pelvic portion of the urethra was anastomosed to the preputial epithelium, creating a urethropreputial conduit. Postoperatively, positive-contrast radiography demonstrated continuity of the anastomoses, and both pigs were able to urinate normally. The pig with the urethropreputial anastomosis developed hematuria and nocturia that were controlled by continuous administration of antibiotics and resolved following cleansing of the preputial diverticulum 1 year after surgery. Extrapelvic urinary diversion should be considered for permanent resolution of urethral obstruction in Vietnamese pot-bellied pigs; urethral anastomosis is preferable to urethropreputial anastomosis, because of the greater risk of ascending urinary tract infection associated with urethropreputial anastomosis.

Anastomosis, Surgical↗
PubMed1994

Use of an ultrasonic Doppler flow detector for determining tissue viability in a dog.

An 8-month-old sexually intact female Boxer was examined because of an almost complete disarticulation of the right thoracic limb at the level of the proximal phalanges. Viability of the tissue distal to the injury was considered questionable. An ultrasonic Doppler flow detector was used to determine that circulation to the portion of the digits distal to the injury had been preserved on the palmar aspect of the foot. Orthopedic repair of the fractures of the third and fourth digits and primary skin closure of the wound was performed. Infection and instability at the fracture sites resulted in pseudoarthrosis and a valgus deformity of the digits distal to the injury. The ultrasonic Doppler flow detector provided a simple noninvasive method for determining tissue viability in the severely traumatized foot of this dog.

Animals↗