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Biomedical subjects

J Mast

Publications and source records attributed to J Mast.

36 records · Page 2Linked to original sources
PubMed1998

High-level expression of Chlamydia psittaci major outer membrane protein in COS cells and in skeletal muscles of turkeys.

The omp1 genes encoding the major outer membrane proteins (MOMPs) of avian Chlamydia psittaci serovar A and D strains were cloned and sequenced. The nucleotide sequences of the avian C. psittaci serovar A and D MOMP genes were found to be 98.9 and 87.8% identical, respectively, to that of the avian C. psittaci serovar A strain 6BC, 84.6 and 99.8% identical to that of the avian C. psittaci serovar D strain NJ1, 79.1 and 81.1% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, 60.9 and 62.5% identical to that of the Chlamydia trachomatis L2 strain, and 57.5 and 60.4% identical to that of the Chlamydia pneumoniae IOL-207 strain. The serovar A or D MOMPs were cloned in the mammalian expression plasmid pcDNA1. When pcDNA1/MOMP A or pcDNA1/MOMP D was introduced into COS7 cells, a 40-kDa protein that was identical in size, antigenicity, and electrophoretic mobility to native MOMP was produced. Recombinant MOMP (rMOMP) was located in the cytoplasm of transfected COS7 cells as well as in the plasma membrane and was immunoaccessible. Intramuscular administration of pcDNA1/MOMP in specific-pathogen-free turkeys resulted in local expression of rMOMP in its native conformation, after which anti-MOMP antibodies appeared in the serum.

Amino Acid Sequence↗
PubMed1997

Expression of beta 2 integrins on blood leukocytes of cows with or without bovine leukocyte adhesion deficiency.

Peripheral blood leukocytes of 11 normal cows, 7 cows heterozygous and 2 heifers homozygous for bovine leukocyte adhesion deficiency (BLAD) were analysed by flow cytometry for the intensity of their beta 2 integrin expression (LFA-1(CD11a/CD18), CR3 (CD11b/CD18) and CR4 (CD11c/CD18)). BLAD-homozygotes revealed no or a very weak expression of the beta 2 integrins and had a 10-fold and 4- to 5-fold increase in absolute number of neutrophils and monocytes, respectively, whereas the absolute number of lymphocytes remained normal. The mean fluorescence intensity (MFI) of the beta 2 integrins (CD18) in heterozygous animals was 56 to 90% of this in the normal cows (MFI between 14 and 512). The difference in the expression level was most pronounced for LFA-1 on the small cluster of lymphocytes with the highest MFI for LFA-1. Repeated analysis and phorbol myristate acetate stimulation revealed that the LFA-1 expression on this high-expressing cell population of the peripheral blood allowed a ready identification of BLAD-heterozygotes by flow cytometry.

Animals↗
PubMed1997

Transolecranon fracture-dislocation of the elbow.

OBJECTIVE: To characterize the prevalence, morphology, and prognosis of anterior (transolecranon) fracture-dislocations of the elbow. DESIGN: Retrospective case series. SETTING: A consecutive series of thirteen patients from a single level-one trauma center, plus four patients from the practices of two of the senior authors. PATIENTS: Three of seventeen patients had simple, oblique fractures of the olecranon, and fourteen had complex, comminuted fractures of the proximal ulna, including fragmentation of the olecranon in seven patients, large coronoid fragments in eight patients, and segmental fractures of the ulna in six patients. Fourteen patients were male and three were female, with an average age of thirty-eight years (range, 18 to 78 years). INTERVENTION: All fractures were treated by open reduction and internal fixation. Two one-third tubular plates had to be revised to 3.5-millimeter dynamic compression plates within six weeks of the initial operation. MAIN OUTCOME MEASURE: Elbow performance rating of Broberg and Morrey. RESULTS: At an average follow-up of twenty-five months, overall outcome was rated as excellent in seven patients, good in eight, and fair in two. Mild posttraumatic arthritis was noted in only two patients. Large coronoid fragments and extensive comminution of the trochlear notch did not preclude a good result provided that stable, anatomic fixation was achieved. CONCLUSIONS: Anterior elbow dislocations occur most often as a fracture-dislocation in which the distal humerus is driven through the olecranon, thereby causing a complex, comminuted fracture of the proximal ulna. This injury is frequently confused with anterior Monteggia lesions by virtue of the readily apparent radiocapitellar dislocation. Stable restoration of the appropriate contour and dimensions of the trochlear notch of the ulna will lead to a good result in most cases.

Adolescent↗
PubMed1997

Comparison of measures of visual acuity in infants: Teller acuity cards and sweep visual evoked potentials.

PURPOSE: This study compares the development of acuity in the same infants during one testing session using Teller acuity cards (TAC) and sweep visual evoked potentials (sVEP). We asked whether different testing methods in two centers would produce different developmental time courses. METHODS: Forty-eight infants were tested in two centers. The standard procedure for TAC was used. For sVEP acuity, the amplitude response curve derived from time-locked cortical activity was used to extrapolate to zero response, giving an acuity estimate for each infant. RESULTS: sVEP acuity was generally higher than TAC acuity. The rate of development was steeper for TAC than sVEP acuity with TAC starting at a much lower level. The ratio of sVEP to TAC acuity decreased exponentially with age reaching an asymptote of about 1.44 at 6 months. CONCLUSIONS: Results were indistinguishable between centers suggesting that comparison of acuity measures obtained using variations of these methods across centers is possible.

Aging↗
PubMed1995

Chlamydia psittaci in turkeys: pathogenesis of infections in avian serovars A, B and D.

At 7 days of age, 4 groups, each of twenty specific pathogen free turkeys kept in isolation units were inoculated by aerosol with the Texas Turkey strain (avian Chlamydia psittaci serovar D), strain 92/1293 (avian Chlamydia psittaci serovar D), strain 84/55 (avian Chlamydia psittaci serovar A) or strain 89/1326 (avian Chlamydia psittaci serovar B). A fifth group of 4 specific pathogen free turkeys were sham inoculated controls. At daily intervals for 10 days and then twice weekly up to 34 days post infection, one bird in each group was killed and the target tissues and cells for replication and the sequence of events of serovar A, B and D infections was examined. In these turkeys, the primary site of replication was the respiratory tract. Chlamydial replication could be detected in the respiratory tract on day 1 post inoculation (p.i.) for group A, on day 3 p.i. for group B and on day 1 to 2 p.i. for groups D1 and D2. Subsequently, there was chlamydaemia and localisation in the digestive tract, in one or more parenchymatous organs, in the pericardium and in the conjunctivae. Specific immunoperoxidase staining revealed chamydiae in these organs in epithelial cells and in monomorphonuclear cells in all infected groups. The monomorphonuclear cells were identified as macrophages by double immunofluorescence staining. Chlamydiae were present in the same tissues for serovars A and D, but could not be demonstrated in proventriculus, duodenum, pancreas, ovaries and testes for serovar B. Furthermore, the intensity of replication was similar for all serovars. However, for serovar B in comparison with the other serovars, the bacteria appeared in most tissues 1 to 6 days later and the maximal replication in these tissues occurred 3 to 4 days later.

Aerosols↗
PubMed1994

Intraoperative evoked potential monitoring in acetabular surgery.

The effectiveness of intraoperative sciatic nerve monitoring was evaluated for 88 consecutive patients undergoing open reduction and internal fixation for acetabular fractures. Intervention outcomes and pre and postoperative electrophysiologic status were compared to postoperative functional findings. Only 2% of the patients demonstrated iatrogenic sciatic nerve palsies. Functional and evoked potential findings were in agreement for 89% of the patients with postoperative palsies, while 26% of the functionally normal patients showed abnormal evoked potentials. Intervention occurred in 55 surgeries; 80% of interventions involved the peroneal nerve. Forty one of the 55 patients who had interventions based on evoked potential results showed recovery of responses to baseline. Of the 14 patients with incomplete intervention recovery, 11 showed impaired postoperative responses. Patients with preoperative evoked potential abnormalities did not show increased susceptibility to iatrogenic evoked potential changes.

Acetabulum↗
PubMed1992

The salvage of open grade IIIB ankle and talus fractures.

Between 1983 and 1989, 11 open grade IIIB ankle or talus fractures were treated according to protocol including debridement, temporary placement of antibiotic beads, soft tissue coverage (including seven free vascular tissue transfers), intravenous antibiotics and fusion using an anterior plate, and bone graft. All patients had a minimum of three separate hospitalizations. Each had at least five operative procedures performed with an average of 8.2/patient (range: 5-12). The total in-patient hospital stay averaged 61.6 days (20-107 days) and in patient costs averaged $62,174.43/patient (range: $33,535.06-$143,847.45). Overall hospital cost averaged $1,009.32/day. Follow-up averaged 47.8 months (range 32-85 months), with an average time to union of 4.4 months. Fusion rate and muscle flap success was 100%. Although fusion and eradication of infection in this specific group of patients was possible, significant functional and psychosocial disability remained. Eight of eleven patients had significant pain, difficulty with stairs, and limited ambulation. All changed jobs or were unemployed. Patients with open grade IIIB tibiotalar injuries with significant bone loss may therefore benefit from early amputation. A multicenter randomized clinical outcome study is needed.

Activities of Daily Living↗
PubMed1991

A new statistic for steady-state evoked potentials.

Steady-state evoked potentials are often characterized by the amplitude and phase of the Fourier component at one or more frequencies of interest. We introduce a new statistic for the evaluation of these Fourier components. This statistic, denoted T2circ, is based on the same physiologic assumptions concerning the sources of variability of a Fourier component that are made in the use of the Rayleigh phase-coherence statistic as well as the standard T2 statistic (Hotelling 1931) for multivariate data. However, the T2circ statistic also exploits the relationship between the real and imaginary components of Fourier estimates, which is not exploited by T2, and utilizes amplitude information, which is ignored by the Rayleigh criterion. For these reasons, the T2circ statistic is more efficient than previously used criteria for detection and quantitation of steady-state responses, both in principle and in practice.

Adult↗
PubMed1991

Fluctuations of steady-state VEPs: interaction of driven evoked potentials and the EEG.

We performed a detailed analysis of the variability of a steady-state human evoked potential (EP) and the spectral properties of the simultaneously recorded electroencephalogram (EEG). This allowed us to determine whether the background EEG was influenced by the evoked potential stimulus, and to what extent variability of evoked potential estimates is simply due to the addition of the background EEG. Steady-state visual evoked potentials (VEPs) were elicited by a checkerboard undergoing contrast-reversal modulation at 1 of 3 fundamental frequencies f: 5.0 Hz, 7.5 Hz, and 10.0 Hz. To a first approximation, the evoked potential (at frequency 2 f) and the undriven components of the EEG combined linearly. However, two kinds of interactions were present: (i) patterned visual stimulation decreased the power in the undriven EEG in the 5-17 Hz range by as much as a factor of 2; (ii) superimposed on this overall effect of pattern stimulation, there were changes in the EEG power at specific harmonics of the input frequency. Power increased by as much as 6-fold at the stimulus reversal rate (2 f) and its second harmonic (4 f). These findings imply a complex non-linear interaction between the visual input and the EEG.

Adult↗
PubMed1990

[Peri-acetabular reorientation osteotomy].

A new technique to plan and perform a reorientation pelvic osteotomy around the hip joint in adolescents and adults is described. Planning is based on 3-dimensional reconstruction of the hip joint. The operation is simulated by computer before surgery to find the correction angles which optimize alignment both quantitatively (amount of femoral head covered) as well as qualitatively (joint congruency). These angles are then utilized at the time of surgery. A Smith-Petersen approach is always used to perform the osteotomy. The pelvic ring is not displaced, but nevertheless the acetabular fragment can be tilted without limitation around all 3 axes. Furthermore, linear displacement permits medialization of a lateralized hip joint. Stability is obtained by simple screw fixation. The posterior column remains mechanically intact, and thus no cast is required. Since 1984, about 200 peri-acetabular osteotomies have been performed. The success of correction was evaluated on plain radiographs using A P and "false profile" views as well as by CT. Conventional radiographs showed fully normalized VCE (Wiberg) and VCA (de Sèze and Lequesne) angles and well-centered joints on the CT-based reconstructions. Four types of complications occurred: there were 2 cases with intra articular extension of the osteotomy; 1 transient femoral neuropraxia; 2 non-unions and 4 cases with ectopic ossifications which limited motion of the joint. The latter problem appear to have been eliminated by the administration of prophylactic indomethacin. Symptomatic fixation screws had to be removed after union in 13 cases.

Acetabulum↗
PubMed1984

Internal fixation technique in pathological fractures of the extremities.

More often than not, the standard methods of internal fixation are insufficient to meet the demands of treatment of pathological fractures. In malignant diseases with improved survival rates, durability of the osteosynthesis is needed. The seemingly convenient prosthetic replacement therefore has to be regarded with caution. Good results without complications cannot be expected unless the fixation of the components is in healthy bone. In the younger patient with a curable disease, late complications have to be considered. We describe methods of internal fixation that satisfy these particular requirements, and pertinent clinical examples elucidate the techniques.

Adult↗
PubMedDate not supplied

Association of Streptococcus gallolyticus strains of high and low virulence with the intestinal tract of pigeons.

We investigated the ability of a high virulence (STR 357) and a low virulence (STR 598) strain of Streptococcus gallolyticus to attach to the intestinal tract of pigeons. For that purpose, first of all, two groups of six pigeons were anesthetized and ligatures were placed at the beginning of duodenum, jejunum, ileum, and colon. The obtained intestinal loops of the birds of the first and second group were injected with S. gallolyticus strains STR 357 and STR 598, respectively. At 15, 30, and 60 min postinoculation, two pigeons of each group were euthanatized and the various intestinal loops were sampled for histologic, immunohistochemical, and electron microscopic examination. Both the high and low virulence strains were able to adhere to the intestinal mucosa. Indeed, all samples dearly showed numerous coccal-shaped bacteria that stained positively with S. gallolyticus antiserum and were lining up against the intestinal epithelium. Likewise, on electron microscopic examination, cocci were seen in the mucus covering the intestinal epithelium. Second, the association of S. gallyticus strains of differing virulence with the intestinal tissue was determined quantitatively. Experiments were performed as described above. The number of S. gallolyticus bacteria that adhered to the intestinal epithelium was determined by plating out 10-fold serial dilutions of the segments. No significant differences in the number of adhered bacteria were found between the strains of high and low virulence.

Animals↗
PubMedDate not supplied

Maternal cocaine abuse: the spectrum of radiologic abnormalities in the neonatal CNS.

The purpose of this study was to determine the pattern and frequency of CNS abnormalities in the offspring of cocaine-abusing mothers. The study group consisted of a retrospective review of all neonates born or admitted to our neonatal intensive care unit over a 1-year period who met criteria for maternal cocaine abuse (43 patients). A control group (62 patients) was obtained from patients seen during the same interval and the cases were matched for gestational age and race. The radiologic studies were analyzed by two independent reviewers, and CNS abnormalities were assessed by means of sonography, CT, or MR. By matching the study and control groups for gestational age, we eliminated the higher frequency of prematurity. This allowed us to determine if maternal cocaine use was associated with any intracranial abnormalities other than those seen with prematurity. The frequency of intracranial hemorrhage, ventricular enlargement, and periventricular leukomalacia was not significantly different between the study and control groups. The frequency of cortical infarction was 17% in the study group and 2% in the control group. The frequency of major congenital malformation was 12% in the study group and 0% in the control group. All five of the congenital malformations seen were midline CNS abnormalities, particularly neural tube defects. It is postulated that the higher statistically significant frequency of stroke and congenital malformations in the babies of maternal cocaine abusers is related to vasospasm caused by cocaine when used in the third and first trimesters, respectively.

Brain↗