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Biomedical subjects

T W Wright

Publications and source records attributed to T W Wright.

At least 37 records · Page 2Linked to original sources
PubMed1996

Excursion and strain of the median nerve.

Five fresh-frozen transthoracic cadaver specimens (ten upper extremities) were dissected in order to measure excursion and strain of the median nerve at the wrist and the elbow in association with different positions of the shoulder, elbow, wrist, and fingers. The relationships between motions of the joints and excursion and strain at the wrist and the elbow as well as between excursion and strain were also determined. When the wrist was moved from 60 degrees of extension to 65 degrees of flexion, the median nerve at the wrist underwent a mean total excursion of 19.6 millimeters (9.2 +/- 1.38 millimeters [mean and standard deviation] in extension and 10.4 +/- 1.50 millimeters in flexion). The change in strain was not measurable secondary to nerve-wrinkling. Motion of the fingers from hyperextension to full flexion caused a mean total excursion of 9.7 millimeters (6.3 +/- 1.31 millimeters in hyperextension and 3.4 +/- 1.04 millimeters in flexion) and a change in strain of 19.0 per cent. This change in strain became more pronounced when the wrist and the fingers moved in synergy. Such strain, if constant, has been shown to decrease microvascular perfusion and nerve conduction in rabbits. With motion of the shoulder, the mean total excursion of the median nerve at the elbow was 9.1 millimeters (4.4 +/- 1.64 millimeters in abduction and 4.7 +/- 1.81 millimeters in adduction) and the change in strain was 13.3 per cent. With motion of the elbow, the mean total excursion was 12.3 millimeters (12.3 +/- 4.20 millimeters in flexion and zero millimeters in the resting position) and the change in strain was not measurable because of the wrinkle effect in flexion. With motion of the wrist, the mean total excursion was 5.6 millimeters (4.3 +/- 1.95 millimeters in extension and 1.25 +/- 0.81 millimeters in flexion) and the change in strain was 14.8 per cent. With motion of the fingers, the mean total, excursion was 3.4 millimeters (2.6 +/- 1.13 millimeters in hyperextension and 0.80 +/- 0.92 millimeter in flexion) and the change in strain was 10.3 per cent. Motion of the wrist and the fingers induced profound excursion of the median nerve at the wrist, whereas motion of the shoulder and the elbow induced marked excursion of the median nerve at the elbow. These excursions were much more pronounced when a number of joints were moved in a composite manner. Any factor that might limit normal excursion, such as scarring, could induce strains that could adversely affect the function of the median nerve. The finding that the position and movement of the limb had a profound effect on excursion and strain of the median nerve at the wrist and the elbow may aid in the understanding of the pathophysiology of median-nerve neuropathy.

Cadaver↗
PubMed1995

Cloning and characterization of a lung-specific cDNA corresponding to the gamma chain of hepatic fibrinogen.

The gene (gamma FBG) encoding the fibrinogen gamma chain (gamma FBG) has been shown to exhibit both tissue-specific and ubiquitous expression. To confirm the identity of the gamma FBG transcripts expressed in extrahepatic tissue, lung tissue was chosen as a model of extrahepatic gamma FBG gene expression. A ferret lung cDNA clone bank was constructed in lambda gt11 and several positive plaques were isolated using cross-species hybridization with the rat gamma FBG cDNA. Sequence data of the longest clone, designated pFLG gamma 3, was compared at the nucleotide and deduced amino acid (aa) levels with sequences of gamma FBG from other species. The results indicated that the identity of the ferret lung-specific gamma FBG cDNA to pig, rat, bovine and human gamma FBG cDNAs ranged from 78-88%; the similarity of the ferret lung-specific gamma FBG deduced aa sequence ranged from 84-88% across species. Cysteine aa involved in intra- and inter-chain disulfide-bonded secondary and tertiary structure are absolutely conserved in ferret gamma FBG. The putative cell-cell adhesion sites for both platelet alpha IIb beta 3 and intercellular adhesion molecule-1 receptor binding to ferret gamma FBG are > 90% similar to the corresponding sites in the human gamma FBG. The results of Northern hybridization indicated that the ferret lung gamma FBG mRNA was equivalent in size to the liver gamma FBG mRNA; Southern hybridization suggested that ferret gamma FBG is a single-copy gene, as is the gamma FBG of other species. Lung-specific gamma FBG expression was localized to epithelial cells of the large and small airways and chondrocytes by in situ RNA:RNA hybridization. The functional significance of gamma FBG expression in lung is not presently known. Since expression of FBG is up-regulated 2-10-fold in the liver during an inflammatory event, it is possible that lung-specific gamma FBG expression occurs predominantly during lung disease or injury.

Amino Acid Sequence↗
PubMed1995

Cloning and characterization of a conserved region of human and rhesus macaque Pneumocystis carinii gpA.

Although the genes encoding Pneumocystis carinii (Pc) glycoprotein A (gpA) display a high degree of host species-specific genotypic diversity, the Pc gpA derived from different host species share defined regions of significant homology in their primary amino acid (aa) structure. Using two degenerate oligodeoxyribonucleotide (oligo) primers corresponding to a conserved Cys region (Cys-primers) of the ferret (F), rat (R) and mouse (M) PcgpA, a 306-bp portion of the human (H) PcgpA was amplified from only one of three known HPc-infected lung samples using PCR. The deduced aa sequence of the HPc PCR product was 72% similar to the corresponding region of a published HPc gpA aa sequence. Because the conserved Cys-primers amplified only one of three samples of HPcgpA, a primer-pair was designed from sequences internal to the Cys-primer sequences of the HPcgpA PCR product (hPc). The hPc primers amplified the expected 254-bp product from each of the three HPc-infected lung DNA samples, suggesting that the Cys-primers may have either amplified a HPcgpA present in fewer copies in the genome of HPc or, alternatively, amplified a gene from an uncommon strain of Pc encoding an isoform variant of gpA not present in the other human isolates analyzed in this report. Restriction analysis of the amplified products demonstrated heterogeneity in the internal sequence, confirming that more than one gpA exists in HPc as well. To determine the relationship of HPcgpA to the gpA of Pc from another primate, the hPc primers were used successfully to amplify a 261-bp product from Pc-infected Rhesus macaque (Rm) lung genomic DNA. These results are consistent with our earlier findings that closely related host species are infected with Pc organisms encoding similar gpA, suggesting that the evolutionary divergence of Pc followed that of the mammalian host species.

Animals↗
PubMed1995

Prosthetic usage in major upper extremity amputations.

Patterns of use of contemporary prostheses by 135 patients with major upper extremity amputations were evaluated by questionnaire. Eighty-four percent of the patients were male and 16% were female. Amputation levels represented were below elbow, 44%; above elbow, 40%; and shoulder disarticulations or forequarter amputations, 16%. The follow-up interval averaged 12 years (range, 1-67 years). One hundred and thirteen patients were fitted with either a myoelectric or body-powered prosthesis. The overall rejection rate was 38%. Thirty-nine of 42 in the below-elbow amputation group used the prosthesis and appeared to benefit the most. Eight of 141 in the wrist disarticulation group used the prosthesis: as did 9 of 21 in the above-elbow amputation group. In contrast, all bilateral amputees used their prostheses. Stiff shoulders and brachial plexus injury were both predictors for poor prosthetic usage.

Amputees↗
PubMed1995

Isoform diversity and tandem duplication of the glycoprotein A gene in ferret Pneumocystis carinii.

Two ferret P. carinii gpA cDNA clones were identified that reacted identically with a panel of anti-gpA monoclonal antibodies, although their nucleotide sequences were 22% divergent. Each clone hybridized to a single mRNA species of 3,600 nucleotides only in P. carinii-infected lung mRNA, but RT-PCR analysis demonstrated that these cDNA clones were derived from two distinct gpA mRNA transcripts. Further PCR analysis demonstrated that the ferret P. carinii genome contains at least two gpA genes lying in tandem on a single chromosome separated by a 329-bp intergenic region. Based on the terminal gene sequences of this tandem repeat and the cDNA clones, a composite full-length ferret P. carinii gpA coding sequence was constructed. The intergenic region immediately downstream of the stop codon of the first gpA gene contains three putative polyadenylation signals, and constitutes the 3' untranslated region (UTR) of the gpA mRNA. Primer extension of the gpA mRNA resulted in products extending 74 and 244 nucleotides into the 5' UTR. However, the intergenic region lying greater than 25 nucleotides upstream of the first methionine of the second gpA gene was found to be absent from the 5' UTR.

Amino Acid Sequence↗
PubMed1995

Humeral fractures after shoulder arthroplasty.

Nine humeral fractures occurred subsequent to 499 shoulder arthroplasties that had been performed between December 1978 and November 1987 at the Mayo Clinic. The time from the arthroplasty to the fracture averaged thirty-nine months (range, eight to 101 months). Seven patients were women and two were men, and the average age was seventy years (range, forty-five to eighty-five years). The arthroplasties were performed for rheumatoid arthritis in five patients and for the sequelae of trauma in four. Six patients had advanced osteopenia, and two had had an ipsilateral total elbow arthroplasty. Six of the fractures were centered at the tip of the prosthesis; one fracture (type A) extended proximally, and five (type B) did not. The three remaining fractures (type C) involved the humeral shaft distal to the implant and extended into the distal humeral metaphysis. Four fractures healed with non-operative treatment. Two fractures that had unacceptable alignment were treated successfully with operative intervention. Three fractures that were treated with immobilization in a splint failed to heal; two of those fractures eventually united after a revision of the prosthesis and bone-grafting was performed, and one fracture remained ununited. Radial nerve palsy developed postoperatively in two patients, and it resolved within three months. Five patients had poor active motion before the fracture, and two of them had even less motion after the fracture was treated. Our experience suggests that long oblique and spiral fractures can be successfully treated non-operatively, provided that the skeletal alignment is acceptable.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Carpal instability non-dissociative.

A retrospective study of 45 patients with symptoms of wrist pain and weakness with clinical evidence of instability is presented. These patients had normal intrinsic interosseous ligaments demonstrated arthrographically or surgically. They were followed for a minimum of 18 months and an average of 5.8 years. All patients demonstrated instability of the proximal carpal row which is referred to as carpal instability non-dissociative (CIND). Seven patients were treated non-operatively and 38 were treated operatively. Surgical management consisted of soft tissue reconstruction directed at the area of instability in 34 cases, joint levelling osteotomy in six, three of whom also had soft tissue reconstructions, and mid-carpal fusion in one. The overall good and excellent results were a disappointing 56% and there was no significant difference between the non-surgical and surgical groups. The best results were found in the ulna-minus CIND patients who underwent a joint levelling osteotomy, with 83% good and excellent results. CIND is associated with extrinsic ligamentous laxity; however, significant difficulty exists in locating the precise areas of maximum pathology. This accounts for the unpredictable results of treatment. As our understanding of the pathomechanics of CIND improves, the treatment will become more specific and the results should improve.

Adolescent↗
PubMed1994

Incidence of ligament lesions and associated degenerative changes in the elderly wrist.

The scapholunate, lunotriquetral, and triangular fibrocartilage of 62 cadaveric wrists were examined to determine the incidence of pathologic changes in asymptomatic elderly wrists. A scapholunate ligament lesion was noted in 18 wrists; the majority of defects were incomplete and involved the central portion of the ligament only. Lunotriquetral ligament defects were noted in 20 wrists; eight were partial defects, most of them were central ligament lesions. Triangular fibrocartilage defects were present in 33 wrists and consisted of two distinct patterns: a central oval pattern with actual tissue loss and a linear defect running in the dorsal anterior direction 2-3 mm ulnar to the radial attachment of the triangular fibrocartilage. X-ray film evaluation showed few significant degenerative changes with no pronounced collapse deformities. Defects involving the scapholunate, lunotriquetral, or triangular fibrocartilage were very common, with the presence of at least one of these ligament defects in wrists. These ligament defects occur as a process of aging and behave in a manner quite different from traumatic lesions of these same structures in the younger population.

Aged↗
PubMed1994

Anterior wrist ganglion.

This study examined the treatment of anterior wrist ganglions by aspiration and injection or surgical excision. Eighty-four patients treated for an anterior wrist ganglion were studied, with an average followup period of 5 years. Initial treatment by aspiration and injection with corticosteroid was performed in 24 patients, with recurrence in 20. A second aspiration and injection was associated with recurrence in all. Of the 72 patients who underwent surgical excision 14 experienced a recurrence of the ganglion. Four patients with a recurrence underwent a second surgical procedure with successful excision in two patients. The origin of the majority of surgically treated ganglions was on the scaphotrapeziotrapezoid joint and radiocarpal joint. Because of a large number of recurrences after nonoperative treatment, surgical excision is recommended as the primary definitive treatment for anterior wrist ganglions Aspiration and injection may provide palliative relief of symptoms.

Adolescent↗
PubMed1994

Conserved sequence homology of cysteine-rich regions in genes encoding glycoprotein A in Pneumocystis carinii derived from different host species.

Pneumocystis carinii surface glycoprotein A (gpA) exhibits host species-specific phenotypic and genotypic variation. Despite this heterogeneity, the gpAs of P. carinii isolated from different host species appear to be homologous molecules sharing certain biochemical and antigenic characteristics. Using two degenerate oligodeoxyribonucleotide primers corresponding to conserved cysteine regions from ferret and rat P. carinii gpAs, a PCR product of approximately 300 bp was amplified from ferret, rat, and SCID mouse P. carinii-infected lung genomic DNA. Northern (RNA) hybridization revealed a transcript of 3,450 nucleotides in P. carinii-infected SCID mouse lung mRNA, which is similar in size to the transcripts for ferret and rat P. carinii gpAs. Nucleotide sequence analysis of SCID mouse P. carinii gpA subclones derived from the PCR products identified two isoforms, which were 89% identical to each other in the amplified region and 73 and 54% identical to the rat- and ferret-derived P. carinii gpA genes, respectively. Comparison of the deduced amino acid sequences of mouse, ferret, and rat P. carinii gpAs revealed striking similarity in residues adjacent to and including the conserved cysteines. Furthermore, the spacing of two proline residues is invariant, and a potential N-linked glycosylation site is found at a similar position in all of the gpAs. Despite the heterogeneity observed in P. carinii gpAs, the conservation of cysteine residues and adjacent sequences implies similar secondary structure and, most likely, similar function for the gpAs of P. carinii isolated from different host species.

Amino Acid Sequence↗
PubMed1993

Purification and functional characterization of homodimeric gamma B-gamma B fibrinogen from rat plasma.

Heterogeneity in the human and rat plasma fibrinogen (FBG) gamma chains is due to differential splicing of the primary gamma chain mRNA transcript. The subunit composition of FBG containing the predominant form of the gamma chain is homodimeric (human: A alpha 2, B beta 2, gamma 50-gamma 50; rat: A alpha 2, B beta 2, gamma A-gamma A). The subunit composition of FBG containing the longer, minor form of the gamma chain is heterodimeric (human: A alpha 2, B beta 2, gamma 50-gamma 57.5; rat: A alpha 2, B beta 2, gamma A-gamma B). The variant gamma chain-FBGs comprise about 10% of the total plasma FBG in the human and 30% in the rat. Although the presence of homodimeric gamma B-gamma B FBG has been speculated, proof of its existence has been difficult to obtain experimentally. We now show that 5% to 6% of rat plasma FBG is found as homodimeric FBG with a subunit composition of A alpha 2, B beta 2, gamma B-gamma B. Commercially purified rat FBG was further purified by diethylaminoethyl-Sephacel chromatography with a combined pH and ionic strength gradient. The enriched gamma B-gamma B FBG fraction eluted at the lowest pH (6.3) and highest ionic strength (4.5 mmho) due to its increased net negative charge. To further purify gamma B-gamma B FBG, a Mono Q column with an NaCl gradient was used. The subunit composition of the purified gamma B-gamma B FBG was confirmed by its electrophoretic mobility under reducing and denaturing conditions both as FBG, and clotted and cross-linked fibrin. Homodimeric gamma B-gamma B FBG was unable to support adenosine diphosphate (ADP)-induced platelet aggregation, whereas heterodimeric gamma A-gamma B FBG was able to support ADP-induced platelet aggregation at 40% of that achieved with homodimeric gamma A-gamma A FBG, similar to previous observations with human FBGs. Taken together, these results support the hypothesis that the A alpha-RGD sites alone are not sufficient for dimeric FBG support of platelet aggregation. Furthermore, the data suggest that at least one intact platelet recognition site at the carboxyterminus of the gamma A or gamma 50 chain is required.

Amino Acid Sequence↗
PubMed1993

Further evidence of host species-specific variation in antigens of Pneumocystis carinii using the polymerase chain reaction.

To further elucidate the extent of variation among Pneumocystis carinii obtained from different mammalian hosts, polymerase chain reaction (PCR) analysis of the genes encoding two antigens of P. carinii was done. Using primers based on the ferret P. carinii glycoprotein (gp)A gene and the rat P. carinii 45- to 55-kDa antigen gene, amplification was attempted with DNA isolated from P. carinii-infected ferret, rat, mouse, and human lungs. For both genes, amplification was successful only with P. carinii DNA isolated from the same host species from which the P. carinii gene was originally isolated. The presence of P. carinii DNA in each sample was documented by PCR using primers based on the conserved mitochondrial ribosomal RNA gene sequence. These results were confirmed for P. carinii gpA by Southern blot analysis using a labeled fragment of the ferret P. carinii gpA gene as a probe. Thus, in addition to the previously reported phenotypic variation among antigens of P. carinii, there is also genotypic variation of these same antigens.

Acquired Immunodeficiency Syndrome↗
PubMed1993

In situ hybridization analysis of developmental stages of Pneumocystis carinii that are transcriptionally active for a major surface glycoprotein gene.

An abundant glycoprotein on the surface of Pneumocystis carinii, termed gpA or gp120, is thought to play a role in the interaction of this opportunistic pathogen with its host. Using RNA:RNA hybridization techniques, the in situ expression of gpA mRNA in developmental forms of the organism was investigated in a ferret model of P. carinii pneumonia. The results suggested that the relative abundance of gpA-specific mRNA was variable in different developmental stages of ferret P. carinii. P. carinii localized along the epithelial lining of alveoli were transcriptionally active. Immunocytochemical detection of gpA and Giemsa staining suggested that many of these organisms were trophic forms of P. carinii. While no detectable gpA mRNA signal was found in the majority of P. carinii cysts, a portion of identifiable cysts co-localized with significant levels of gpA mRNA signal. Differential staining of the cyst wall with Gomori's methenamine silver suggested that the transcriptionally active P. carinii cysts were the intermediate or precyst forms of the organism, while the cysts with no detectable mRNA signal were either mature or empty (excysted). Alveolar macrophages were observed surrounded by transcriptionally active organisms; however, no gpA-transcriptional activity was detected within macrophages. Taken together, the results suggest that transcription of gpA occurs in forms of P. carinii that are actively replicating, and in close proximity or contact with, alveolar epithelial cells.

Animals↗
PubMed1993

Reconstruction of the humerus with an intramedullary fibular graft. A clinical and biomechanical study.

Nine patients with nonunited humeral shaft fractures were treated by open reduction and internal fixation with an intramedullary fibular bone graft and a compression plate. Fixation of the screws was enhanced by passing them through the fibula as well as the two humeral cortices (quadricortical fixation). Eight of the nine fractures united at an average of 3.5 months. Tests on cadaver bones showed that quadricortical fixation was as strong as methylmethacrylate augmentation and significantly better than bicortical fixation.

Adult↗
PubMed1992

Expression and characterization of a cDNA clone encoding an immunodominant surface glycoprotein of Pneumocystis carinii.

Most studies of antigens of Pneumocystis carinii have focused on an abundant, immunogenic 95- to 140-kDa surface glycoprotein referred to as gpA. Expression cloning of gpA from P. carinii obtained from ferrets resulted in isolation of colinear fragments of gpA cDNA encoding approximately 87 kDa of the core protein. Northern hybridization detected an abundant, single species of gpA-specific mRNA of 3600 nucleotides. Southern hybridization revealed gpA-specific bands only in P. carinii-infected lung genomic DNA, suggesting that gpA cDNA did not result from induction of a host lung gene. Antiserum raised against a fragment of recombinant gpA detected P. carinii cysts and isolated native P. carinii gpA, indicating retention of epitopes between the nonglycosylated recombinant gpA and glycosylated native gpA. The deduced amino acid sequence is hydrophilic and contains 12 potential N-linked glycosylation sites and 47 cysteine residues, consistent with the surface orientation of gpA on the organism and other known characteristics of the native molecule.

Amino Acid Sequence↗
PubMed1988

Excision of the hook of the hamate: a retrospective survey and review of the literature.

Fractures of the hook of the hamate frequently fail to unite. In symptomatic nonunion, surgical excision of the hook has provided relief of pain in the few reported cases. In a survey of surgeons, 133 cases of excision of the hook to treat nonunion were reviewed retrospectively. The complication rate associated with excision is three percent. These complications, such as injury to the ulnar nerve or the superficial palmar arch and median nerve paresthesias secondary to retraction are due more to the surgical exposure than the actual excision.

Carpal Bones↗