Polyaxonal myelination in a human leprous nerve.
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Adolescent↗
Biomedical subjects
V Shetty
Publications and source records attributed to V Shetty.
Biomechanical rationale for surgical-orthodontic expansion of the adult maxilla.
OBJECTIVE: To develop a biomechanical rationale for surgical-orthodontic correction of transverse maxillary deficiencies in adults by clarifying the internal stress responses to rapid palatal expansion in a photoelastic model. MATERIALS AND METHODS: A three-dimensional photoelastic analog of an adult human skull was constructed by fabricating the individual facial bones from a photoelastic material and fixing them along their anatomic sutural areas. After determining the force-activation characteristics of a Hyrax expansion appliance in a straining frame, the appliance was applied to the analog and incrementally activated. The stresses developing at the different craniofacial areas were visualized and photographed in the field of a circular polariscope. Sequential cuts were performed to simulate midpalatal, zygomatic buttress, and pterygomaxillary osteotomies, and the alterations in the internal stress responses were recorded after each individual cut. RESULTS: The force-activation characteristics of the Hyrax appliance are in the orthopedic range (500 g). The magnitude and distribution of the stresses induced by appliance activation differed notably between the simulated osteotomies. Analysis of fringe patterns showed that the midpalatal and pterygomaxillary articulations were the primary anatomic sites of resistance to expansion forces. The patterns of distribution and the increase in the magnitude of the stresses at superior sutural location were particularly pronounced after the pterygomaxillary cuts. The forces produced by the Hyrax appliance had deep anatomic effects, with internal stresses also manifesting at regions distant from the site of force application. CONCLUSIONS: Based on photoelastic observation, it may be concluded that complete midpalatal and pterygomaxillary osteotomies are essential for predictable skeletal expansion in adults. Exclusive use of bilateral zygomatic buttress osteotomies appears to be inadequate. The expansion forces exerted by the Hyrax appliance are orthopedic in nature and produce deep anatomic effects. Clinicians should be aware that the craniofacial stresses produced by appliance activation may be experienced by the patient as pain or discomfort.
Adult↗
Novel in situ double labeling for simultaneous detection of proliferation and apoptosis.
We describe a novel double-labeling method to simultaneously investigate proliferation and apoptosis from plastic-embedded biopsy specimens (PEBs). Infusions of bromo- and/or iododeoxyuridine (BrdU/IudR) were given to 10 patients, five with acute myeloid leukemia (AML) and five with myelodysplastic syndromes (MDS), and S-phase cells were measured in PEBs using a monoclonal anti-IudR/BrdU antibody. Apoptosis was measured by in situ end-labeling (ISEL) of DNA. The results demonstrate that both AML and MDS are highly proliferative disorders but that there is almost no apoptosis in the former, whereas extensive apoptosis was observed in the latter. Double labeling revealed that large numbers of S-phase cells in MDS were simultaneously undergoing apoptosis. We conclude that the high cell death in MDS cancels the high cell birth, resulting in a functionally aplastic marrow and thus accounting for the observed ineffective hematopoiesis. On the other hand, AML is rapidly fatal, probably owing to high cell birth with no or minimal cell death. Therapeutic strategies to prevent intramedullary programmed cell death of hematopoietic precursors should be evaluated in MDS, and efficacy of chemotherapy in AML can be assessed by measuring the induction of apoptosis in post-treatment biopsy specimens.
Acute Disease↗
Thermography for the clinical assessment of inferior alveolar nerve deficit: a pilot study.
Neurosensory deficit is a major complication encountered in maxillofacial surgery. This study assessed the ability of electronic thermography to identify inferior alveolar nerve deficits in a pilot clinical study. The study population comprised six patients with inferior alveolar nerve deficit and 12 normal subjects. Frontally projected facial thermograms were taken on 18 subjects and measured using an Agema 870 unit and thermal image computer. Mathematical analysis of thermal measurements included temperature and delta T calculations of the anatomic zone over the mental region of the face. Results included (1) high levels of thermal symmetry of the chin in normal subjects (delta T = 0.1 degree C, standard deviation = 0.1 degree C); (2) low levels of thermal symmetry in patients with inferior alveolar nerve deficits (delta T = +0.5 degree C, standard deviation = 0.2 degree C); (3) statistically significant differences in delta T values (t = 4.82, P > .001) in patients with inferior alveolar nerve deficit; and (4) absolute temperature variations of the mental region in both groups. This pilot study demonstrated thermal asymmetry in patients with inferior alveolar nerve deficit and suggests that electronic thermography has promise as a simple, objective, noninvasive method for evaluating nerve deficits. However, more extensive studies are needed before thermographic procedures are accepted clinically.
Adult↗
Thermographic assessment of reversible inferior alveolar nerve deficit.
The purpose of this study was to investigate thermography's potential as a diagnostic alternative for evaluating neurosensory deficits of the inferior alveolar nerve. Electronic thermography was used to evaluate the alterations in facial thermal patterns attendant to a conduction defect of the inferior alveolar nerve induced in 12 subjects using 2% lidocaine. The rates of onset and duration of sensory block, as visualized by thermography, were related to the results of conventional neurosensory testing. Comparison of the rate of response change within each measurement system revealed that changes in facial skin temperature manifest the induced deficit earlier than discriminative tests. Also, the prolonged elevation of thermal asymmetry suggested that electronic thermography has the ability to detect subtle changes in nerve function that are not discernible by physical neurosensory tests relying on patient response. Although cutaneous temperature increases were highest in the field of observation near the sensory distribution of the mental nerve, an inexplicable warming of the contralateral side of the face and neck was also observed. These attendant findings emphasize the need for further studies on the pathophysiologic mechanisms of facial thermal changes to better understand thermography's diagnostic accuracy and clinical utility for monitoring inferior alveolar nerve dysfunction.
Adult↗
A multicenter, case-controlled study of the clinical presentation and etiology of ascites and of the safety and clinical efficacy of diagnostic abdominal paracentesis in HIV seropositive patients.
OBJECTIVE: To analyze the clinical presentation and etiology of ascites in HIV seropositive patients compared with the general population and to analyze the safety and clinical efficacy of abdominal paracentesis in HIV patients. METHODS: We did a multiyear study of 24 HIV seropositive and 60 control patients with ascites undergoing diagnostic abdominal paracentesis at two university hospitals. RESULTS: HIV seropositive patients presented with similar clinical findings as other patients with ascites, except HIV patients had a significantly higher incidence of pyrexia and a lower serum albumin level and leukocyte count. The two groups had similar mean ascitic fluid values of lactate dehydrogenase, total protein, glucose, and erythrocyte count. HIV patients had a trend of a higher rate of infected ascites than controls (29% vs 12%; odds ratio = 3.12; odds ratio confidence interval = 0.80-12.3; p < 0.06; chi 2). HIV and control patients with culture-proven bacterial peritonitis had similar ascitic fluid leukocyte and absolute neutrophil counts. In eight (33%) of the HIV patients, major new diagnoses were made from ascitic fluid analysis, including spontaneous bacterial peritonitis in four, tuberculous ascites in two, fungal peritonitis in one, and lymphoma in one (control rate = 30%; not significantly different; chi 2). The HIV patients did not experience any complications from paracentesis, whereas the controls experienced one minor complication of prolonged drainage of ascitic fluid from the paracentesis site (not significantly different rates; Fisher's exact test). Six (25%) of the HIV patients had ascites caused by AIDS-defining illnesses of lymphoma, peritoneal tuberculosis, or disseminated candidiasis. CONCLUSIONS: Abdominal paracentesis is a safe and effective clinical diagnostic tool in HIV patients. In addition to standard tests, ascitic fluid should be sent for mycobacterial and mycological histological stains and cultures in HIV patients. AIDS-unrelated causes are the most common cause of ascites in HIV patients, with only about 1/4 of cases due to AIDS-related diseases.
Adult↗
Immunological, ultrastructural and molecular features of unclassifiable acute leukaemia.
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Acute Disease↗
Use of sodium hyaluronate in treating temporomandibular joint disorders: a randomized, double-blind, placebo-controlled clinical trial.
This study assessed the efficacy of high-molecular-weight sodium hyaluronate as a treatment for certain intracapsular temporomandibular joint (TMJ) disorders. One hundred twenty-one patients were studied at three test sites using a randomized, double-blind, placebo-controlled experimental design. Patients were selected on the basis of 1) confirmed diagnosis of either degenerative joint disease (DJD), reducing displaced disc (DDR), or nonreducing displaced disc (DDN); 2) nonresponsiveness to nonsurgical therapies; and 3) severe dysfunction as established by the Helkimo indices (HI), visual analog scales (VASs), and physical measurements of joint movement and joint noise (arthrophonometry [APM]). Subjects received a unilateral upper joint space injection of either 1) 1% sodium hyaluronate in physiologic saline (MedChem Products, Woburn, MA) or 2) USP physiologic saline. Clinical evaluations were performed using HI, VAS, and APM at weekly intervals for the first month and then at monthly intervals up to 6 months postinjection. Statistical analyses for both categorical and continuous variables were performed for each diagnostic category at each examination interval. For DJD, no difference in outcome was seen between treatment groups. For DDN, significant between-group differences were seen through 1 month; however, beyond this time point, the number of DDN patients was insufficient to draw meaningful conclusions concerning efficacy. For DDR, statistically significant within-group and between-group improvement in all three measures (HI, VAS, APM) was seen for the hyaluronate group compared to the saline group throughout the 6-month test period. At the month-2 and month-3 examination intervals, twice as many patients treated with hyaluronate (90%) showed improvement compared to patients given placebo. Further, only 3% of patients with DDR who were treated with hyaluronate relapsed compared with 31% of patients with DDR given placebo.
Adult↗
Immunological and ultrastructural studies in acute biphenotypic leukaemia.
AIMS: To compare the sensitivity of the ultrastructural method to detect myeloperoxidase (MPO) with light microscopy and immunocytochemistry using an anti-MPO antibody; to examine the expression of lymphoid antigens in relation to MPO activity in blast cells from cases of biphenotypic leukaemia. METHODS: Blast cells from 14 cases of biphenotypic acute leukaemia were analysed. Immunological markers were performed by single or double immunofluorescence staining on a flow cytometer. The presence of MPO was determined by light microscopy, electron microscopy on fixed and unfixed cells, and by immunoalkaline phosphatase with an anti-MPO antibody. The immunogold method was applied at the ultrastructural level to assess the expression of lymphoid and myeloid antigens at the same time as the MPO activity. RESULTS: Six of the 14 cases were initially classified as acute lymphoblastic leukaemia (ALL) and eight as acute myeloid leukaemia (AML). MPO activity was shown at the ultrastructural level in 4-99% blasts from all cases. Six of the 14 were MPO negative by light microscopy and three of these were negative with the antibody anti-MPO. Coexpression of lymphoid antigens (CD19, CD10, or CD2) and MPO was shown by the immunogold method in four out of 11 cases; in seven cases the blasts coexpressed myeloid antigens (CD13, CD33) and MPO. CONCLUSIONS: Electron microscopy is more sensitive for showing MPO than light microscopy and immunocytochemistry; the immunogold method combined with MPO used at the ultrastructural level can help to define the cell lineage involved in biphenotypic leukaemia by highlighting the myeloid component defined by MPO.
Acute Disease↗
Biomechanical validation of the solitary lag screw technique for reducing mandibular angle fractures.
The purpose of this study was to determine whether the solitary lag screw technique meets the biomechanical demands of angle fractures. Simulated angle fractures in four cadaveric mandibles were reduced using solitary lag screws and the load-displacement relationships determined under functional loading of the individual mandibles. Subsequently, an angle fracture in a photoelastic mandible analog was fixed with a lag screw and subjected to similar loading. The mechanisms by which the solitary lag screw transferred functional loading were observed and recorded in a circular polariscope. Concomitant distraction tendencies were monitored and measured using displacement transducers. Correlation of the force-displacement measurements to photoelastic observation substantiated that the solitary lag screw functions as a tension band to provide a sufficient degree of interfragmentary compression and stability to withstand functional loading of the mandible.
Biomechanical Phenomena↗
The role of an anti-myeloperoxidase antibody in the diagnosis and classification of acute leukaemia: a comparison with light and electron microscopy cytochemistry.
The enzyme myeloperoxidase (MPO) is the hallmark of the myeloid lineage. We have analysed the presence of MPO in blasts from 180 cases of acute leukaemia (103 acute myeloid leukaemia (AML) and 77 acute lymphoid leukaemia (ALL) by means of monoclonal antibodies anti-MPO and immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase method). The aim of the study was to investigate the specificity and sensitivity of this marker compared with MPO cytochemistry by light (LM) and electron microscopy (EM), and with the expression of myeloid antigens. Anti-MPO was positive (greater than 3% blasts) in all but one of the 90 AML positive by LM cytochemistry. Of 13 AML cases negative by MPO cytochemistry, six showed 3-10% blasts reactive with anti-MPO and were also positive with antibodies to CD13 and/or CD33. The presence of MPO was confirmed in four of these by EM. The overall positivity of anti-MPO in AML was 92%. Anti-MPO was negative in all but two ALL (6% and 8% positive blasts). The blasts in these two cases were also CD13, CD33 and MPO positive by EM; both were thus reclassified as biphenotypic. Another two ALL reinterpreted as biphenotypic were negative by MPO cytochemistry and anti-MPO but were MPO positive by EM and with CD13 and/or CD33. We conclude that anti-MPO is a sensitive and specific early marker of myeloid blasts and should be incorporated in the routine immunophenotyping of acute leukaemia.
Acute Disease↗
A classification of acute leukaemia for the 1990s.
The need for reproducibility in the classification of acute leukaemia has made it necessary to incorporate information derived from new techniques which have become essential for the study of these disorders. In addition to classic morphology and cytochemistry (FAB proposals), it is necessary to add immunology and cytogenetics (MIC proposals), as well as to investigate further the biological and diagnostic significance of molecular events. As a result of these investigations a new group of leukaemias merit recognition as distinct entities. These include three types of ALL with specific chromosome abnormalities, namely, i) t (9;22), ii) t (4;11) and iii) t (1;19) and four subtypes of AML, i) with minimal differentiation or AML-M0, ii) with basophilic precursors or M2Baso, iii) AML (M4/M5) with t (8;16) and iv) AML with trilineage myelodysplasia. Biphenotypic acute leukaemia constitutes also a distinct entity with features of ALL and AML and represents a malignancy probably affecting multipotent stem cells. We propose an objective evaluation system for biphenotypic leukaemias based on a score in which the various lineage markers are graded according to their known specificity.
Humans↗
Preparation and evaluation of a nonproprietary bilayer skin substitute.
Cross-linked, allogeneic, telopeptide-depleted dermal grafts were lyophilized and laminated with silicone rubber elastomer. Resultant bilayers were studied for incorporation into the wound site and capacity to inhibit cutaneous wound contraction in experimental animals. Bilateral full-thickness skin wounds were made in 20 male New Zealand white rabbits. One side was grafted with the processed graft, while the contralateral side remained ungrafted as a control wound. Over 63 days, wound sites were analyzed at intervals on the basis of the extent and rate of wound contraction and by histologic examination. Cutaneous wounds successfully incorporated graft matrix and were significantly inhibited in their rate and extent of wound contraction. Notably, by day 63, grafted wounds retained 71 percent of their original area, whereas ungrafted control wounds retained only 16 percent of their original area. There were no graft rejections, and the bilayer graft's dermal analogue appeared to function as a biodegradable template that physically conformed neodermis to a preestablished pattern while counteracting contractile forces. This investigation suggests that, in experimental animals, the success of bilayer dermal grafts is less dependent on highly specialized and complex preparative techniques than typically has been presumed and that relatively simple, previously published, nonproprietary techniques, when adapted to a bilayer format, yield acceptable results as defined in terms of biocompatibility, capacity for graft incorporation, and inhibition of wound contraction.
Animals↗
Alloplastic materials in reconstructive periodontal surgery.
Alloplastic implants, especially those made with calcium phosphate ceramics, are being increasingly used in reconstructive periodontal surgery. Despite attractive generic features such as good biocompatibility, these ceramic implants differ significantly from each other in terms of biologic profile. Variations in source material used, manufacturing process, and physical and chemical properties determine the clinical utility of these implants. Porous hydroxyapatites currently are favored, especially those with natural morphologic characteristics. These ceramic implants appear to serve as biocompatible fillers that accelerate bone healing when used for the right clinical indications. It is anticipated that alloplastic implants eventually will form a part of the periodontist's armamentarium.
Alveoloplasty↗
Phenotypic, genotypic, cytochemical, and ultrastructural characterization of acute undifferentiated leukemia.
During the diagnostic investigation of 750 acute leukemias, nine cases were morphologically, cytochemically, and phenotypically undifferentiated. In seven of these cases the blasts were class II+, CD34+ and TdT+, in one were class II+, TdT+, CD7+ while in the remaining leukemia blasts expressed class II only. Cytoplasmic and membrane CD22, CD3, CD13, and Ig as well as membrane CD19, CD10, CD37, CD2, CD33, CD14, glycophorin C, and CD61 were absent. The further characterization of these rare leukemias yielded the following results. The TCR-beta, -gamma and -delta genes were in germline configuration in seven cases studied while IgH genes were rearranged on both alleles in two cases and germline in the other five. By ultrastructural analysis peroxidase activity was detected on unfixed cells in a minority of blasts from four of seven cases. In two of the peroxidase-positive cases a small proportion of blasts also reacted with an anti-myeloperoxidase monoclonal antibody. In one of the peroxidase-negative cases, 7% of blasts were labeled by the antibody, suggesting the presence of peroxidase in its proenzyme form. Importantly, the two cases with Ig gene rearrangements did not have cytochemically or immunologically detectable peroxidase. Three of the nine patients were treated as ALL while six received AML chemotherapy. In five patients complete remission was achieved while the other four died from infections during remission induction. Four patients are still in remission 7, 12, 24, and 30 months after diagnosis while one patient relapsed after 12 months. In conclusion, we have characterized the genotypic and ultrastructural features of subtype of acute leukemia in which blasts expressed immaturity markers and lacked lineage associated antigens. In contrast to previously reported "unclassifiable" cases, the leukemias were phenotypically homogeneous and showed a good response to chemotherapy.
Acute Disease↗
Technical improvements in the sagittal split ramus osteotomy.
This article addresses the potential sources of morbidity associated with the sagittal split ramus osteotomy. Refinements in the instrumentation and technique are described; these enhance the exactness of the procedure, thereby minimizing the complications and improving the stability of the surgical result.
Bone Plates↗
Localisation of retained roots by fibre-optic transillumination.
The rationale for the use of fibre-optic transillumination in the location of residual roots is discussed and the technique is described.
Humans↗