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Biomedical subjects

D N Collins

Publications and source records attributed to D N Collins.

At least 19 recordsLinked to original sources
PubMed1998

Identification of persistent infection in experimental syphilis by PCR.

The studies described herein were designed to evaluate the usefulness of the PCR in detecting persistent syphilitic infection. Three groups of animals were used: a nonimmune group infected with Treponema pallidum (NI/TP), a nonimmune group injected with heat-killed treponemes (NI/HKTP), and an immune and reinfected group (I/TP). All animals were inoculated with similar numbers of organisms distributed at 10 sites on the clipped back and in both testes. The persistence of the treponemes was examined by PCR and the rabbit infectivity test (RIT). The kinetic studies and statistical analysis of their results demonstrated that the rate of bacterial clearance from the NI/TP group was very low and incomplete at 4 months after infection. It was significantly different from those of both the NI/HKTP (P < 0.001) and I/TP (P < 0.05) groups. No statistically significant differences in treponemal elimination were found between the NI/HKTP and I/TP groups. PCR can detect the DNA of dead organisms, but the latter are eliminated by the host relatively quickly (15 to 30 days) as compared to elimination of live treponemes (>120 days). PCR results correlated well with RIT results. These data suggest that PCR-positive specimens obtained from an untreated patient(s) or collected weeks after treatment indicate persistent infection. They also show that the process of elimination of T. pallidum from primary sites of infection is prolonged and incomplete.

Animals↗
PubMed1998

Infection of the laboratory mouse with the intracellular pathogen Ehrlichia chaffeensis.

To determine the basis of susceptibility and resistance to human monocytic ehrlichiosis (HME), immunocompetent and immunocompromised mice were infected with Ehrlichia chaffeensis and bacterial loads were measured by PCR and by immunohistochemistry. Immunocompetent (C. B-17 and C57BL/6) mice cleared the bacteria within 10 days, but immunocompromised SCID and SCID/BEIGE mice developed persistent infection in the spleen, liver, peritoneal cavity, brain, lung, and bone marrow and became moribund within 24 days. Both immunocompromised strains lack T and B lymphocytes, but the SCID/BEIGE strain is also deficient in natural killer (NK) cell function. During advanced stages of disease, the infections were associated with wasting, splenomegaly, lymphadenopathy, liver granulomas and necroses, intravascular coagulation, and granulomatous inflammation. Histochemical and immunohistochemical localization studies confirmed the presence of bacteria in tissues, and viable bacteria were cultured from infected animals. The data reveal that T and/or B cells play an essential role during resistance of immunocompetent mice to infection with E. chaffeensis and demonstrate the utility of immunocompromised mice as an experimental model for the study of HME.

Animals↗
PubMed1997

Arthroplasty for arthritis and rotator cuff deficiency.

Massive and irreparable loss of rotator cuff tendon integrity can be associated with the development of glenohumeral and acromiohumeral arthritis. Loss of glenohumeral instability provided by the rotator cuff may initiate and perpetuate this unique condition of the shoulder. Proximal humeral replacement arthroplasty is the preferred surgical treatment; special techniques of this procedure are presented. Patients are gratified by the durable restoration of comfort and, to a lesser extent, function.

Aged↗
PubMed1997

Differential recruitment of B and T cells in coxsackievirus B4-induced pancreatitis is influenced by a capsid protein.

Two genetically similar variants of coxsackievirus B4, CB4-P and CB4-V, cause distinct disease syndromes in mice. A multidisciplinary approach was used to examine the events occurring in situ. The CB4-P variant induced acute pancreatitis, followed by repair of the exocrine tissues, while the CB4-V variant induced chronic pancreatitis, characterized by extensive destruction of the exocrine tissues. Since CB4-V replicated more efficiently than CB4-P in vivo, the more extensive tissue injury associated with CB4-V infection could be explained as the result of a higher level of viral replication. However, the fact that CB4-V replicated more efficiently in a mouse strain that survives infection than in a strain that succumbs to infection suggests that immune-mediated mechanisms as well as viral cytolysis may contribute to pancreatic tissue injury. To address the role of the immune system in virus-induced pancreatitis, the cell types within the inflammatory infiltrate were analyzed by flow cytometry. B cells (34 to 75%) were the most abundant, followed by T cells (10 to 30%), natural killer cells (4 to 8%), and macrophages (0 to 6%). Recruitment (and perhaps proliferation) of B and T cells to the pancreatic tissues was influenced by viral strain. Differential recruitment of T and B cells may reflect altered antigenic sites between CB4-P and CB4-V. The viral sequence that affected T- and B-cell recruitment was identified as a threonine residue at position 129 of the VP1 capsid protein.

Animals↗
PubMed1995

A point mutation in the VP4 coding sequence of coxsackievirus B4 influences virulence.

In analyzing the molecular determinants of virulence of coxsackievirus B4, chimeric viruses were constructed from avirulent and virulent viruses. The vCB424 recombinant contained a single nucleotide substitution on an avirulent genetic background, resulting in replacement of Ser-16 of VP4 with Arg-16. Mice infected with vCB424 displayed an intermediate phenotype.

Amino Acid Sequence↗
PubMed1993

Developments in three-dimensional stereo brightfield microscopy.

We present recent developments of a widefield computer/microscope system and image reconstruction algorithm for producing three-dimensional (3D) increased depth of field images in the form of brightfield stereo pairs of thick specimens. The theoretical principle of this image reconstruction technique is based on Weiner-type inverse filtering. A number of extensions and refinements to our previous work have included further testing of the system with a broader class of specimens and the implementation of several pragmatic refinements important for future 3D microscopy systems. These refinements include histogram modification routines for improving visualization, a preprocessing routine to eliminate edge artifacts due to circular convolution and other effects, stereo viewing angle optimization, a rule of thumb estimate for the axial sampling rate, and incorporation of a variation of the Fast Fourier Transform and filtering operations that significantly reduce computational time. Images of spyrogyra, neonatal rat hippocampal neurons, and cervical/vaginal cell smears are presented to show the utility of these methods for 3D visualization. The primary advantages of these methods are that they operate with an ordinary transmitted light microscope and are inexpensively implemented on a personal computer with reasonable computation time.

Algorithms↗
PubMed1992

Vena caval filter use in orthopaedic trauma patients with recognized preoperative venous thromboembolic disease.

This study comprises a series of 35 patients with pelvic or lower extremity fractures requiring surgery who also had a documented significant acute deep venous thrombosis (DVT). The authors treated these with low-dose Coumadin and 36 vena caval filters, which were used prophylactically prior to surgery. The patients received low-dose warfarin after placement of the vena caval filters and were maintained at 1.3-1.5 times the prothrombin control value for 6 weeks to 3 months. In this group of patients, there were no fatal pulmonary emboli and no clinically significant complications from filter placement. There were nine asymptomatic filter complications demonstrated radiographically in eight patients. Additionally, one patient with a tilted vena caval filter required placement of another filter. The combination of vena caval filters and low-dose warfarin appears to be a successful and relatively safe method of managing those patients who have acute DVT and require surgery for their pelvic or lower extremity fractures.

Combined Modality Therapy↗
PubMed1991

Arthrography of painful hips following arthroplasty: digital versus plain film subtraction.

Digital and manual subtraction images obtained during the arthrographic evaluation of 78 painful hip prostheses were reviewed retrospectively. Revision arthroplasty was performed in 53 of these cases, and the arthrographic and surgical findings were correlated. The digital and manual subtraction images were evaluated without knowledge of the surgical results using established criteria for component loosening. Digital subtraction arthrography of the femoral component demonstrated a 96% sensitivity and 100% specificity for the diagnosis of component loosening. Sensitivity and specificity for acetabular component loosening were 83% and 80%, respectively. Plain film subtraction of the femoral component demonstrated a 79% sensitivity and 100% specificity; the sensitivity and specificity for the acetabular component were 75% and 80%, respectively. The difference between detection of femoral component loosening on digital as opposed to manual subtraction images was statistically significant (P less than 0.05). This study demonstrate that digital subtraction improves the evaluation of femoral component loosening in painful hip prostheses.

Arthrography↗
PubMed1991

Postoperative urinary retention associated with total hip and total knee arthroplasties.

Urinary retention following total hip and knee arthroplasty is a common problem frequently necessitating either prolonged urethral catheter drainage or intermittent catheterization. The direct relationship of urinary tract instrumentations, procedures, and infections to deep sepsis in total hip replacements is well documented. Pharmacologic therapy to stimulate voiding or augment bladder emptying is thus theoretically preferable to the use of catheterization. Prasozin hydrochloride, an alpha blocker, relaxes the smooth musculature of the posterior urethra and prostrate and has been used to treat urinary obstruction secondary to benign prostatic hypertrophy. A prospective study in 60 male patients showed a statistically significant decrease in postoperative urinary retention with the perioperative administration of prazosin (p less than 0.01). A higher incidence of urinary tract infection was seen in patients who developed urinary retention (3% versus 20%) (p less than 0.01). Uroflowmetry parameters were not predictive of the patient at risk for retention and were unaltered with the administration of prazosin. Prazosin can be an effective adjunct in the prophylaxis of postoperative urinary tract infections and may decrease the potential risk for total joint sepsis.

Aged↗
PubMed1991

Noncemented porous-coated anatomic total hip arthroplasty.

In 1984, as an alternate to the acrylic fixation of the components of total hip arthroplasty, the use of an uncemented porous-coated anatomic (PCA) hip system with a beaded porous coating to achieve biologic fixation was initiated. Since then, 44 patients with cementless acetabular components and 35 patients with cementless femoral components have been followed for a minimum of 24 months and an average of 37 months. Harris hip scores averaged 90.5 at most recent follow-up intervals. No reoperations were necessary for failures of fixation or change in position of the acetabular component. Ominous roentgenographic signs such as progressive bead shedding, progressive radiolucencies, or progressive component migration have not occurred. Two femoral component revisions have been necessary: one for intractable pain and one for pain and roentgenographic loosening. Although thigh pain has been prevalent (20%), all patients have been accommodated and have retained stable hip scores. Progressive radiolucencies and progressive implant subsidence have been rare occurrences. The authors continue to use the cementless acetabular component in all cases of total hip arthroplasty in which initial stability can be obtained. It is their preference to cement the femoral component in patients over 65 or when initial stability cannot be achieved.

Acetabulum↗
PubMed1991

Infections at the site of a hip implant. Successful and unsuccessful management.

Thirty-four patients developed the complication of deep infection at the site of a hip implant (n = 35). Multiple factors in existence at the time of implant placement and the time of presentation with infection as well as the therapeutic regimen were retrospectively analyzed. Patients with successful outcomes (n = 15) were relatively younger (mean, 52 years) compared to those that had an unsuccessful outcome (n = 19; mean, 65 years; p less than 0.01). No other factors were predictive of the outcome of treatment. Implant extirpation, expedient wound closure, and, when necessary, muscle transposition favored a successful outcome. Implant retention and open wound packing resulted in prolonged wound healing and, sometimes, hip disarticulation or death.

Adult↗
PubMed1991

Cervical spine instability in rheumatoid patients having total hip or knee arthroplasty.

The records and roentgenographs of 113 rheumatoid patients treated by total hip or knee arthroplasty were analyzed retrospectively. The cervical spine roentgenographs were evaluated for significant atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. One or more of these findings were present in 69 (61%) of the patients. Thirty-five of the 69 (50%) with roentgenographically documented cervical spine instability had no signs or symptoms of instability at the time of admission for joint replacement. This high incidence of cervical spine instability in a select population of rheumatoid patients emphasizes the importance of preoperative evaluation of the cervical spine including flexion and extension lateral roentgenographs.

Adolescent↗
PubMed1991

Chronic rupture of the Achilles tendon: a new technique of repair.

A new operative technique is described for the treatment of patients who have a rupture of the Achilles tendon. The large gap between the proximal and distal stumps of the Achilles tendon in seven patients was bridged by use of the tendon of the flexor digitorum longus as the graft. At the most recent follow-up examination (average follow-up, thirty-nine months; range, two to six years), the result was excellent or good in six patients and fair in one. Postoperatively, two patients needed an adjuvant procedure: one, a local rotation flap and the other, a split-thickness skin graft. Both patients had excellent restoration of function. The patient who had a fair result had a persistent limp and residual discomfort. There were no re-ruptures.

Achilles Tendon↗
PubMed1991

Porous-coated anatomic total knee arthroplasty. A prospective analysis comparing cemented and cementless fixation.

The results of 26 cementless porous-coated anatomic (PCA) total knee arthroplasties (TKAs) were analyzed and compared to 25 cemented PCA TKAs. Identical prospective protocols were followed. The mean preoperative and postoperative knee scores at an average three-year follow-up interval (range, two to five years) were 59.6 and 81.5 for cementless knees compared to 57.6 and 80.4 for cemented knees. The difference was not statistically significant (p greater than 0.10). Blood loss was significantly higher in the cementless knees (p = 0.02). Radiolucent lines, loose beads, and tibial component subsidence were more frequent in cementless knees. No differences between cementless and cemented knees were observed in the femoral components. The PCA femoral components implanted without cement compare favorably to those implanted with cement. The PCA tibial and patellar components are more reliably secured with cement.

Adult↗
PubMed1990

Successful use of reaming and intramedullary nailing of the tibia.

The records and radiographs of 87 patients with 88 fractures of the tibial diaphysis who underwent intramedullary reaming and nailing were retrospectively reviewed. The mean patient age was 37 years. Seventy fractures were closed, and 18 were open. The indications for nailing were failures of closed treatment (n = 48), nonunions (n = 24), multiple injuries (n = 14), and fixation of osteotomy (n = 2). Seventy-six patients with 77 nails who were followed for an average of 26.2 months were studied. For acute fractures, the average time to complete clinical and radiographic union was 5.3 months. For established nonunions, the average healing time was 9 months. The only fractures that failed to unit were nonunions developing from previously open Type III injuries. Angular deformities greater than 5 degrees did not occur. Significant tibial shortening occurred in only one fracture. Decreased motion in the ankle or knee was present in six patients. Major complications as a result of tibial nailing occurred in three patients: two deep infections and one patellar tendon rupture. Minor complications included 10 patients with pain at the nail insertion site necessitating removal in four patients, three patients with transient sensory peroneal nerve dysesthesias, and one patient with a superficial wound infection that cleared with local care. Nine patients required reoperation. Intramedullary reaming and nailing of the tibia can be used advantageously in the treatment of difficult fractures of the tibial shaft and their sequelae. Attention to the technical details of nail insertion will minimize the most frequent complications.

Adult↗
PubMed1990

Standard specimens for stain calibration: application to Romanowsky-Giemsa staining.

Standardized specimens with reproducible staining properties were fabricated from extracts of biological objects (bovine liver, nucleoprotamine and defatted muscle). The standard specimens were stained with two formulations of the Romanowsky-Giemsa stain (RG), using the same azure B and eosin Y. One formulation used methanol and Sorensen's buffer and the other DMSO and Hepes buffer as solvents. The standard specimens were stained either in the composite stain or in the individual dyes dissolved in the same solvents and at the same concentration as the composite stain. Solution spectroscopy demonstrated different spectra for the two formulations with some wavelength regions varying by more than an order of magnitude. The RG spectra were also very different from those of the individual dyes dissolved at the RG concentration in the respective solvents. The stained standard specimens were analyzed by microspectrophotometry and were found to have spectra similar to those of cell smears. Furthermore, the standard specimens were shown to be a repeatable substrate for stain uptake. The transmitted light intensity from random fields of the same standardized specimen varied +/- 5%. When specimens were stained at the same time, the specimen-to-specimen variation depended on preparation conditions and the measurement wavelength, but was as good as +/- 5% for some conditions. The quantitative stain performance of both formulations was studied and compared. The standardized specimens provide a tool for the quantitative study of staining processes and specimen preparation procedures and for stain calibration.

Animals↗