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Biomedical subjects

B Patel

Publications and source records attributed to B Patel.

At least 37 records · Page 2Linked to original sources
PubMed1999

Clinical presentation, radiographic findings, and diagnostic methods of pulmonary blastomycosis: a review of 100 consecutive cases.

BACKGROUND: We sought to determine the relationship among radiographic findings, clinical presentation, and diagnostic testing of pulmonary blastomycosis. METHODS: We reviewed the medical records of 100 consecutive patients with pulmonary blastomycosis. RESULTS: Air-space infiltrates were the usual radiographic finding of pulmonary blastomycosis. Mass-like infiltrates were associated more with chronic than acute presentations. Air-space and mass-like infiltrate were predominately involved in the upper lobes. Sputum analysis made the initial diagnosis of blastomycosis most often. Acute and chronic presentations were not different between immunosuppressed patients and the remainder of the patients. In addition, infiltrates on chest radiographs in immunosuppressed patients were similar to the other patients. CONCLUSIONS: In an endemic area, pulmonary blastomycosis should be considered for any pulmonary infiltrate, especially in the upper lobes. Sputum analysis in most cases aids in the diagnosis, but bronchoscopy and/or tissue biopsy should be considered if the suspicion of blastomycosis is high and sputum analysis is inconclusive, negative, or not possible. Follow-up with chest radiographs after antifungal therapy is reasonable until complete resolution or fibrotic changes in patients with pulmonary blastomycosis.

Acute Disease↗
PubMed1999

Warthin's tumor of the parotid salivary gland. A case report.

Neoplasms of the salivary glands are not uncommon. The dentist is in the unique position to make an early diagnosis and refer the patient for definitive treatment. This article will review the clinical appearance, pathology, treatment and potential complications of Warthin's tumor, a benign salivary gland tumor. It describes a case presented at the Salivary Gland Center. Columbia University School of Dental and Oral Surgery, New York Presbyterian Hospital-Columbia Campus.

Adenolymphoma↗
PubMed1998

Disruption of the talin gene compromises focal adhesion assembly in undifferentiated but not differentiated embryonic stem cells.

We have used gene disruption to isolate two talin (-/-) ES cell mutants that contain no intact talin. The undifferentiated cells (a) were unable to spread on gelatin or laminin and grew as rounded colonies, although they were able to spread on fibronectin (b) showed reduced adhesion to laminin, but not fibronectin (c) expressed much reduced levels of beta1 integrin, although levels of alpha5 and alphaV were wild-type (d) were less polarized with increased membrane protrusions compared with a vinculin (-/-) ES cell mutant (e) were unable to assemble vinculin or paxillin-containing focal adhesions or actin stress fibers on fibronectin, whereas vinculin (-/-) ES cells were able to assemble talin-containing focal adhesions. Both talin (-/-) ES cell mutants formed embryoid bodies, but differentiation was restricted to two morphologically distinct cell types. Interestingly, these differentiated talin (-/-) ES cells were able to spread and form focal adhesion-like structures containing vinculin and paxillin on fibronectin. Moreover, the levels of the beta1 integrin subunit were comparable to those in wild-type ES cells. We conclude that talin is essential for beta1 integrin expression and focal adhesion assembly in undifferentiated ES cells, but that a subset of differentiated cells are talin independent for both characteristics.

Actins↗
PubMed1998

The mitochondrial phosphoglyceroyl-ATP-containing polymer, purinogen, is unchanged by cardiac ischaemia and reperfusion but may function in the regulation of free intracellular inorganic phosphate concentrations.

Previous work in our laboratory demonstrating large unexplained systematic variations in the heart contents of free adenine nucleotides led us to propose the existence of some unrecognised sequestered form and thence to the purification of very labile acid-insoluble oligomers which we characterised as oligo[3-phospho-glyceroyl-gamma-triphospho(5')adenosine(3')] , abbreviated to (PG-ATP)n. More recently, we provided evidence that these oligomers appear to be the end chains of a complex polymer located in the mitochondrial intermembrane space of a number of rat tissues. We called this polymer purinogen and devised a means of assaying it quantitively [Patel, B., Sarcina, M. & Mowbray, J. (1994) Eur. J. Biochem. 220, 663-669]. Here we report measurements of purinogen in perfused hearts subjected to moderate and severe global ischaemia and reperfusion. Measurements of tissue and perfusate nucleotides, nucleosides and purine degradation products demonstrate that ischaemia led to the augmentation of the free nucleotide content by up to 30% and its re-sequestration on reperfusion in reversible but not in irreversible ischaemia. The purinogen content was unchanged by ischaemia or reperfusion implying the existence of some other unidentified storage pool. By contrast, glucose addition to glycolytically deprived hearts or removal of Pi from perfusion medium, conditions which might be expected to alter demand for intracellular Pi, led to the quantitative transfer of nucleotides between phosphate-rich purinogen and free nucleotides. The possibility that purinogen may act as a rapidly accessible reservoir of intracellular inorganic phosphate is discussed.

Adenosine Triphosphate↗
PubMed1998

Identification of spermatozoa and round spermatids in the ejaculates of men with spermatogenic failure.

OBJECTIVES: As many as 10% of infertile men have azoospermia caused by spermatogenic failure or ductal obstruction. The histologic diagnoses associated with spermatogenic failure--Sertoli cell-only syndrome, maturation arrest, and hypospermatogenesis--do not necessarily represent global changes in the affected testis, as occasional seminiferous tubules may still produce mature germ cells. Intracytoplasmic sperm injection (ICSI) allows individual sperm that have been isolated from testicular tissue to fertilize oocytes. This study assessed whether mature germ cells (either round spermatids or spermatozoa) were present in the ejaculates of patients with spermatogenic failure. METHODS: All semen analyses performed at our tertiary care institution from January 1993 through December 1995 were reviewed to identify azoospermic men with spermatogenic failure. During this period, our laboratory employed Nuclear-Fast Red and picroindigocarmine staining (NF-PICS) of cytospin slides to identify rare spermatozoa and spermatids in otherwise azoospermic ejaculates. RESULTS: Of 3005 analyses reviewed, 20 azoospermic men whose infertility was solely attributable to spermatogenic failure were identified. The histologic diagnoses were germinal cell aplasia (n = 7), complete maturation arrest (n = 6), incomplete maturation arrest (n = 3), and hypospermatogenesis (n = 4). Using the NF-PICS technique, mature germ cells were identified in the ejaculates of 15 men (75%), and 9 men (45%) had fully formed spermatozoa present. CONCLUSIONS: In the clinical management of azoospermic infertile men, the NF-PICS technique may be used to identify men who have some degree of testicular spermatogenesis. This might obviate the need for the purely diagnostic testis biopsy that is performed before therapeutic biopsy for testicular sperm extraction in conjunction with ICSI.

Biopsy↗
PubMed1998

Anal endosonography in patients with anorectal symptoms after haemorrhoidectomy.

BACKGROUND: Anorectal symptoms after haemorrhoidectomy are common and treatment is often empirical. Because of this, an audit was carried out of the value of anal endosonography in patients with anorectal symptoms after haemorrhoidectomy. METHODS: Between May 1993 and February 1997, 16 patients (ten men and six women of median age 56 (range 35-77) years) were investigated by anal endosonography for anorectal symptoms after haemorrhoidectomy which involved anorectal incontinence (n = 10), anal pain (n = 4) and obstructive defaecation (n = 2). The findings were compared with those in a matched group of asymptomatic patients after haemorroidectomy. RESULTS: Anal endosonography demonstrated an abnormality in 12 symptomatic patients. Of the ten patients with anorectal incontinence, endosonography showed an internal anal sphincter defect (n = 5), a combined sphincter defect (n = 2) and an isolated external anal sphincter defect (n = 1). Normal appearances were seen in all asymptomatic patients. The endosonographic abnormalities of the four patients with anal pain included internal anal sphincter defect (n = 1), extrinsic mass (n = 1), and intersphincteric abscess (n = 1). One of the two patients with obstructive defaecation had an isolated external anal sphincter defect on endosonography. CONCLUSION: These results show a high yield of endosonographic abnormalities in patients who experience symptoms after haemorrhoidectomy. In particular, occult sphincter injury as a cause of incontinence in these patients can frequently be demonstrated.

Adult↗
PubMed1998

New reference reagent for the quality assurance of anti-D antibody detection.

A UK BTS-NIBSC freeze-dried anti-D preparation has been prepared and used to monitor the performance of routine antibody detection tests and of the test operators. With the day-to-day use of this preparation, adverse changes in test performance and in test operator may be detected and appropriate action taken before the effect becomes significant. Two dilutions of this preparation have been defined, one which should be detected unequivocally in every test; the other, more dilute, may not be detected in every test but is used to monitor changes in performance. Experience with the use of this preparation is reported from three test centres undertaking routine antibody detection tests. By monitoring results over a series of working days, significant differences were noted in operator performance within one test centre, as was a reduced sensitivity of a given test system within one test centre compared with the same system in the other test centres. These differences were detected only by monitoring the results obtained with this preparation.

Coombs Test↗
PubMed1998

Characterization of an amorphous deposit in the lamina propria in oral snuff users in the Sudan as collagen.

Histological and ultrastructural features of 25 oral snuff dipper's lesions with distinctive subepithelial hyaline deposits were investigated. Periodic acid-Schiff reaction with and without diastase digestion demonstrated the presence of glycogen and other carbohydrates, but histochemical stains for normal collagen, elastin and fibrin showed a weak variable reactivity of the deposit. Although in 7/25 cases the deposit was in close proximity to labial salivary glands and on occasions ducts were found within the deposit, the presence of mucin was not a consistent feature. Congo red staining and immunohistochemical investigation with an anti-amyloid antibody did not support the previous contention that such deposits were amyloid in nature. Immunohistochemically, collagen antibodies also provided negative results, but ultrastructural features of three biopsies studied suggest that the bulk of this deposit is made up of collagen, as typical cross-striated fibrils were found. The pathogenesis of this deposit could therefore be interpreted as over-production and/or reduced turnover of collagen by resident fibroblasts, which is further altered by the ingredients of toombak. The deposit does not appear to be a secretory product.

Adult↗
PubMed1997

An autoinhibitory control element defines calcium-regulated isoforms of nitric oxide synthase.

Nitric oxide synthases (NOSs) are classified functionally, based on whether calmodulin binding is Ca2+-dependent (cNOS) or Ca2+-independent (iNOS). This key dichotomy has not been defined at the molecular level. Here we show that cNOS isoforms contain a unique polypeptide insert in their FMN binding domains which is not shared with iNOS or other related flavoproteins. Previously identified autoinhibitory domains in calmodulin-regulated enzymes raise the possibility that the polypeptide insert is the autoinhibitory domain of cNOSs. Consistent with this possibility, three-dimensional molecular modeling suggested that the insert originates from a site immediately adjacent to the calmodulin binding sequence. Synthetic peptides derived from the 45-amino acid insert of endothelial NOS were found to potently inhibit binding of calmodulin and activation of cNOS isoforms. This inhibition was associated with peptide binding to NOS, rather than free calmodulin, and inhibition could be reversed by increasing calmodulin concentration. In contrast, insert-derived peptides did not interfere with the arginine site of cNOS, as assessed from [3H]NG-nitro-L-arginine binding, nor did they potently effect iNOS activity. Limited proteolysis studies showed that calmodulin's ability to gate electron flow through cNOSs is associated with displacement of the insert polypeptide; this is the first specific calmodulin-induced change in NOS conformation to be identified. Together, our findings strongly suggest that the insert is an autoinhibitory control element, docking with a site on cNOSs which impedes calmodulin binding and enzymatic activation. The autoinhibitory control element molecularly defines cNOSs and offers a unique target for developing novel NOS activators and inhibitors.

Amino Acid Sequence↗
PubMed1997

Fragile X mental retardation protein is translated near synapses in response to neurotransmitter activation.

Local translation of proteins in distal dendrites is thought to support synaptic structural plasticity. We have previously shown that metabotropic glutamate receptor (mGluR1) stimulation initiates a phosphorylation cascade, triggering rapid association of some mRNAs with translation machinery near synapses, and leading to protein synthesis. To determine the identity of these mRNAs, a cDNA library produced from distal nerve processes was used to screen synaptic polyribosome-associated mRNA. We identified mRNA for the fragile X mental retardation protein (FMRP) in these processes by use of synaptic subcellular fractions, termed synaptoneurosomes. We found that this mRNA associates with translational complexes in synaptoneurosomes within 1-2 min after mGluR1 stimulation of this preparation, and we observed increased expression of FMRP after mGluR1 stimulation. In addition, we found that FMRP is associated with polyribosomal complexes in these fractions. In vivo, we observed FMRP immunoreactivity in spines, dendrites, and somata of the developing rat brain, but not in nuclei or axons. We suggest that rapid production of FMRP near synapses in response to activation may be important for normal maturation of synaptic connections.

Amino Acid Sequence↗
PubMed1997

Monoclonal antibodies recognizing the N- and C-terminal regions of talin disrupt actin stress fibers when microinjected into human fibroblasts.

We have characterized a panel of 6 monoclonal antibodies raised against human platelet talin by Western blotting, immune precipitation, and immunofluorescence, and shown that antibodies TA205 and TD77 disrupt actin stress fibers and focal adhesions, and inhibit cell motility when microinjected into human fibroblasts. Using a series of chick talin fusion proteins spanning the entire length of the molecule, we have mapped the epitopes recognized by these antibodies to the conserved N- and C-terminal regions of the protein. TA205 bound to an epitope contained within residues 139-433, a region which overlaps an F-actin binding site, and which shows homology with the ezrin/radixin/moesin family of cytoskeletal proteins. The epitope recognized by TD77 was located within the C-terminal region of the protein (residues 2269-2541) which also contains an F-actin binding site homologous to that in the yeast actin-binding protein SIa2p. To investigate the possibility that TD77 disrupts actin stress fibers by binding directly to the C-terminal actin binding site, additional talin fusion proteins were generated and analyzed for TD77 and actin binding. Fusion proteins containing residues 2269-2541, 2304-2541, and 2304-2463 all cosedimented with F-actin, whereas TD77 did not recognize the latter fusion protein. These results show that the C-terminal actin-binding site is distinct from the region recognized by the anti-functional antibody TD77, raising the possibility that it binds to a novel functionally important ligand-binding site in the talin molecule.

Actins↗
PubMed1997

Interactions between calcipotriene and ultraviolet light.

BACKGROUND: Calcipotriene is often used with UVB or PUVA, but interactions between UV radiation and calcipotriene have not been examined extensively. OBJECTIVE: Our purpose was to examine interactions between calcipotriene and UV light. METHODS: Minimal erythema doses (MEDs) were determined with UVB and immediate pigment darkening was measured for UVA. The effect of calcipotriene ointment applied before phototesting was examined. Thick and thin applications of calcipotrience were compared. Calcipotriene ointment was applied to a small area on the skin before phototherapy. Patients received either UVB, PUVA, UVA, or no phototherapy. After phototherapy, the ointment was collected and assayed by reverse-phase, high-performance liquid chromatography. RESULTS: MEDs for UVB and immediate pigment darkening for UVA were unaffected by calcipotriene. Thick application of calcipotriene, however, increased the MED, UVA caused substantial reductions in the concentration of detectable calcipotriene. CONCLUSION: When used in conjunction with PUVA, calcipotriene should be applied after exposure to UVA.

Calcitriol↗
PubMed1997

Hypercalcemia in patients with metastatic renal cell carcinoma: effect of nephrectomy and metabolic evaluation.

PURPOSE: The role of nephrectomy in the management of hypercalcemia in metastatic renal carcinoma is not known. Hypercalcemia in patients with renal cell carcinoma frequently mimics primary hyperparathyroidism and has been attributed to tumor secretion of parathyroid hormone related protein. We determined the role of cytoreductive surgery in patients with metastatic renal cell carcinoma and hypercalcemia, identified factors that predict patient benefit from surgery, and evaluated the mechanisms of hypercalcemia in these patients. MATERIALS AND METHODS: A total of 15 patients with metastatic renal cell carcinoma and hypercalcemia underwent metabolic and laboratory evaluation followed by nephrectomy. Post-operatively they were followed for changes in serum calcium levels. We selected 18 normocalcemic patients with metastatic renal cell carcinoma and 4 normocalcemic patients without renal cancer to serve as control groups for survival and parathyroid hormone related protein expression. RESULTS: A decrease in serum calcium corrected for albumin occurred in 9 of 11 patients at 1 to 4 weeks after nephrectomy and in 7 of 12 patients at 5 to 16 weeks after nephrectomy. Clinical evaluation supported a parathyroid hormone related protein mechanism of hypercalcemia in 5 of 8 patients. Two patients had evidence of local osteolytic hypercalcemia and 1 had prostaglandin mediated hypercalcemia. CONCLUSIONS: Nephrectomy temporarily ameliorated hypercalcemia in a subgroup of patients with metastatic renal cancer and hypercalcemia. Parathyroid hormone related protein expression was commonly found to be associated with hypercalcemia. Nonparathyroid hormone related protein mechanisms of hypercalcemia in renal carcinoma may be more common than previously thought.

Adult↗
PubMed1997

Oral staphylococcus in older subjects with rheumatoid arthritis.

OBJECTIVE: To determine if Staphylococcus aureus and Staphylococcus epidermidis, etiologic bacterial agents to late prosthetic joint infections (LPJI), are more prevalent in the oral flora of older individuals with rheumatoid arthritis (RA) than in an age and gender-matched nonarthritic control population (NA). DESIGN: Cultures were obtained from the nares, oropharynx, saliva, tongue, and gingival crevice, and the results were compared between older patients with RA and controls. SETTING: University of Michigan Medical Center, Ann Arbor, VA Medical Center, and University of Michigan School of Dentistry. PARTICIPANTS: A total of 111 community-dwelling subjects with a diagnosis of RA and 83 gender-matched control subjects. MEASUREMENTS: Colistin nalidixic acid agar plates with 5% sheep's blood were inoculated and incubated. Isolates were speciated using the API Staph Trac micro method and catalase and coagulase tests. MAIN RESULTS: Individuals with RA had a higher prevalence of S. aureus isolated from the oral cavity. However, only the oropharynx and tongue revealed higher rates; all other sites were insignificant. The presence of oral S. aureus was associated with xerostomia. Staphylococcus epidermidis was not detected from any of the oral sites sampled. Sixty-two percent (10/16) of the S. aureus isolates from the RA subjects were resistant to penicillin and ampicillin, whereas none were resistant to a cephalosporin. CONCLUSIONS: These findings suggest that rheumatoid arthritis may be a risk factor for LPJI in older prosthetic joint patients undergoing invasive dental procedure in the posterior oral cavity. This increased risk is caused, in part, by a higher prevalence of S. aureus in the posterior oral cavity. The prevalence and the antibiotic resistance of S. aureus must be considered when determining the need for chemoprophylaxis.

Adult↗
PubMed1997

Surgical management of anorectal incontinence due to internal anal sphincter deficiency.

BACKGROUND: The aetiology, surgical management and outcome in 15 patients with anorectal incontinence due to internal and sphincter (IAS) deficiency as a result of previous anal surgery (n = 14) or penetrating trauma (n = 1) was studied. METHODS: The degree of anorectal incontinence was scored by the Cleveland Clinic system; median score was 14 (range 11-16) before surgery. In all patients the anal sphincter mechanism was assessed by endoanal ultrasonography. Thirteen of the 15 patients underwent either rotation (n = 5), island (n = 5) or advancement (n = 3) anoplasty to correct the contour defect in the anal canal. In the remaining two patients direct IAS repair was performed. RESULTS: Four of the 13 patients who underwent anoplasty developed wound breakdown as the result of infection (n = 3) or inadvertent suture removal (n = 1). A defunctioning stoma was required in three of these patients but all of these have been closed. At median follow-up of 34 (range 6-72) months, all patients who underwent anoplasty have normal defaecatory control and a median continence score of 2 (range 0-4). Direct IAS repair produced no symptomatic improvement in either patient. CONCLUSION: These results suggest that anoplasty deserves further evaluation in the treatment of anorectal incontinence due to discrete IAS defects, but that the place of IAS repair remains uncertain.

Adult↗