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Biomedical subjects

D M Simpson

Publications and source records attributed to D M Simpson.

At least 127 records · Page 7Linked to original sources
PubMed1986

In vivo differentiation of progenitor cells of the periodontal ligament. An experimental study using physical barriers.

The present study was designed to test the hypothesis that during regeneration of cementum, the progenitor cells from periodontal ligament must come in contact with root dentin in order to differentiate into cementoblasts. After reflecting mucoperiosteal flaps, fenestration wounds were made in the buccal cortical plates of mandibular canines in 6 beagle dogs. The exposed root surfaces were curretted to remove all cementum. The exposed root surface on one side was demineralized with citric acid while the contralateral wound had saline treatment. The exposed root surfaces were then dried and pieces of Nuclepore membrane (pore size 0.1 mu) were attached to part of the exposed root surface to prevent contact of progenitor cells with root dentin. The fenestration wounds were then covered with Millipore filter to facilitate the population of wounds by progenitor cells from the periodontal ligament. Histologic analysis was performed after 3 months of healing. In specimens where the Nuclepore membrane had remained attached to root dentin, no new cementum was seen over the membrane. At the borders of the wounds and in specimens where the Nuclepore membrane had detached from root dentin, new connective tissue attachment was consistently seen. Also, root resorption was very rarely observed in both the acid-treated and control specimens. The present findings suggest that contact with root dentin may be necessary for progenitor cell differentiation into formative cells like cementoblasts.

Animals↗
PubMed1986

Nitrous oxide: clinical and electrophysiologic investigation of neurologic complications.

Prolonged exposure to nitrous oxide produces a recognized neurologic syndrome. We report clinical and electrophysiologic studies of nervous system involvement in a 25-year-old student who abused nitrous oxide. He developed signs of a sensorimotor polyneuropathy and of myelopathy. Routine blood studies, CSF examination, and myelogram were normal. Clinical electrophysiologic studies were performed serially. Nerve conduction studies demonstrated reduced amplitude and slowed sensory potentials, and mildly prolonged late responses. Sensory evoked potentials revealed prolonged latency of scalp-evoked potentials from tibial nerve stimulation with normal median nerve values. The foveal visual evoked potential was delayed in the right eye, with normal visual acuity, funduscopic examination, and spatial contrast sensitivity. Repeat electrophysiologic studies demonstrated improvement. Nitrous oxide produces multifocal reversible dysfunction within the nervous system similar to that described in patients with vitamin B12 deficiency.

Adult↗
PubMed1986

Improvement in organically disturbed behavior with trazodone treatment.

Four elderly patients with severe organic brain syndromes and disturbed behavior were treated with trazodone after therapy with neuroleptics had been ineffective. The behavior of all four patients improved substantially. In each case, the clinical presentation did not suggest a depressive illness, and many of the disturbed behaviors, such as hypersexuality, are not generally considered characteristic of depression. The improvement in behavior may be related to the taming effect of trazodone in animal models of aggression. This effect is not shared by other antidepressants; thus, trazodone may have unique value as an alternative to neuroleptics for the treatment of organically disturbed behavior.

Aged↗
PubMed1986

Reliability of Andreasen's thought, language and communications disorder scale.

The study of disordered thinking has been hampered by a lack of clinical instruments aimed at the measurement of thought disorder. Andreasen has proposed a rating scale for thought disorder (TLC) and reported on its reliability and preliminary aspects of its validity. In our study, a psychiatrist and physician assistant rated 98 psychiatric inpatients using the TLC and BPRS. Interrater reliability ranged from 0.35 to 0.80 (weighted kappa) on 18 aspects of thought disorder and one global item. The order of reliability for the 18 individual items was strongly correlated between the Andreasen sample and our own (r = 0.77). While the BPRS thought disorder scale was significantly related to the global rating of thought disorder on the TLC (r = 0.71), only half of the variance in thought disorder measured by the TLC was accounted for by the BPRS factor. Thus, this study supports Andreasen's contention that the TLC is a reliable instrument and suggests that the instrument may provide additional information about thinking disorders.

Communication↗
PubMed1985

Measuring thought disorder with clinical rating scales in schizophrenic and nonschizophrenic patients.

The distinction between disorders of thought structure and disorders of thought content in a diagnostically heterogeneous psychiatric population was empirically tested using factor analysis applied to the item scores on two common clinical rating scales, the Brief Psychiatric Rating Scale and Andreasen's Thought, Language, and Communication Scale. The factor structure supported the separation of disordered thinking into disorders of thought content and disorders of thought structure or communication. Additionally, our results indicate that both aspects of disordered thinking are present in schizophrenic and manic patients; neither is specifically characteristic of schizophrenia. Indeed, disordered thought structure appears to be more common or worse in the manic patient than in the schizophrenic patient.

Bipolar Disorder↗
PubMed1985

Low molecular weight measles immunoglobulin M in subacute sclerosing panencephalitis and acute measles.

Thirty eight patients with subacute sclerosing panencephalitis (SSPE) were investigated. Five patients who previously had measles immunoglobulin M (IgM) detected in unfractionated serum and cerebrospinal fluid (CSF) had measles IgM exclusively in the low molecular weight (LMW) fractions of serum and CSF. Measles IgM had previously not been found in unfractionated serum from 33 patients but was detected exclusively in the LMW fractions of serum from 30 patients. Seven children with acute measles had the expected high molecular weight (HMW) measles IgM in serum but 5 also had LMW measles IgM. Four young adults who had had measles in childhood had neither HMW nor LMW measles IgM in their sera.

Acute Disease↗
PubMed1985

An evaluation of the role of antiestrogen-binding sites in mediating the growth modulatory effects of antiestrogens: studies using t-butylphenoxyethyl diethylamine, a compound lacking affinity for the estrogen receptor.

Tert-butylphenoxyethyl diethylamine (BPEA), a compound synthesized by us, was designed to incorporate features important in binding to antiestrogen-binding sites (AEBS) while lacking features important in binding to the estrogen receptor (ER). With this compound, we have addressed the question of the role of AEBS in mediating the growth modulatory effects of antiestrogens. BPEA has an affinity for AEBS 6% that of tamoxifen and an affinity for ER less than 0.0003% that of estradiol. BPEA (10(-11)-10(-6) M) had no effect on the growth of MCF-7 breast cancer cells and no effect on inhibition of the growth of MCF-7 cells by different concentrations of the antiestrogen tamoxifen. In addition, BPEA (even at doses of 1 mg/day X 50 g rat) exhibited no uterotropic or antiuterotropic activity in immature rats and had no influence on the agonistic or antagonistic activity of varying concentrations of tamoxifen on uterine weight. Hence, we conclude that occupancy of AEBS, at least by BPEA, does not modulate growth of the uterus or breast cancer cells and does not influence the potency of tamoxifen as an antiestrogen. These findings raise serious doubts about the role of the AEBS in mediating directly the growth modulatory effects of antiestrogens.

Binding, Competitive↗
PubMed1985

An evaluation of tricalcium phosphate implants in human periodontal osseous defects of two patients.

This study evaluated the use of tricalcium phosphate (TCP) ceramic implant material in periodontal osseous defects. Thirteen defects in two patients were treated with mucoperiosteal flaps and placement of TCP. The defects were evaluated clinically and radiographically utilizing standardized probe placement and radiographic technique. Clinically, there was a mean probing pocket reduction of 4.5 mm as a result of a mean gain of clinical probing attachment level of 2.0 mm and a mean gingival recession of 2.5 mm. Radiographically, there was a mean "fill" of 1.8 mm. Six teeth were removed by block biopsy for histologic analysis, three at 3 months, one at 6 months and two a 9 months. The TCP particles were well tolerated and encapsulated by fibrous connective tissue, but the particles did not stimulate new bone growth. The junctional epithelium ended 1.62 mm coronal to the apical extent of a reference notch placed at the base of the defect. Although new cementum was observed, there was limited evidence of new attachment.

Adult↗
PubMed1985

Phagocytic cells in periodontal defense. Periodontal status of patients with chronic granulomatous disease of childhood.

Both qualitative and quantitative neutrophil abnormalities have been associated with severe forms of periodontitis. Defects in chemotaxis, phagocytosis and bacterial killing have been reported among both peripheral blood and gingival neutrophils harvested from patients with juvenile and rapidly progressive periodontitis. Chronic granulomatous disease of childhood (CGD) is a rare, inherited disorder associated with the occurrence of severe, life-threatening, suppurative infections of skin, liver, lymph nodes and other organs. Neutrophils and monocytes from individuals with CGD lack enzymes necessary for the production of oxygen reduction/products such as H2O2 and superoxide anion, and therefore are unable to kill many species of bacteria and fungi. However, no detailed study of the periodontium of these patients has been undertaken. Accordingly, five patients whose ages ranged from 17 to 32 years were included in this study. An additional (sixth) patient was included based on complete dental records. Neutrophils from all patients demonstrated defective O2 metabolism, and all patients had histories of chronic recurrent abscesses consistent with CGD. All patients were receiving antibiotic prophylaxis. Several patients had ulcerative lesions of the oral cavity of unknown etiology. Examination of the periodontium revealed that three patients had gingivitis, one had localized early periodontitis, and one had generalized early-to-moderate periodontitis. The severity of periodontal disease was consistent with patient age and local etiologic factors. No patients had evidence of juvenile, severe or rapidly-progressing disease in spite of their leukocyte defects. These findings suggest the following possibilities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Effects of mandibular orthognathic treatment on mucogingival tissues.

Twenty-four patients receiving comprehensive orthognathic care including genioplasty were studied to evaluate the effect of orthognathic treatment on the mucogingival complex in the mandibular anterior region. Parameters measured prior to and after therapy were: width of keratinized gingiva, width of attached gingiva and gingival recession. A subjective assessment of tissue thickness was accomplished. A statistically significant decrease in width of both keratinized and attached gingiva was noted following orthognathic therapy in the mandibular anterior area. In six of 24 patients, gingival recession was a clinically significant finding. The actual pretreatment width of keratinized and/or attached tissue did not seem to be the critical factor in development of recession. Risk of recession appeared to increase when genioplasty was combined with mandibular advancement and tended to occur at sites in which the keratinized gingiva and underlying bone appeared thin.

Adolescent↗
PubMed1983

Neurological complications of acquired immune deficiency syndrome: analysis of 50 patients.

Fifty patients with acquired immune deficiency syndrome had complications affecting the central or peripheral nervous systems or both. The patients were either male homosexuals, intravenous drug abusers, or recently arrived Haitian refugees. They ranged in age from 25 to 56. Central nervous system complications were of four kinds: (1) Infections included Toxoplasma gondii abscesses in 5 patients, progressive multifocal leukoencephalopathy in 2, cryptococcal meningitis in 2, Candida albicans in 1, and possible Mycobacterium avium intracellulare in 3. Eighteen patients suffered a subacute encephalitis possibly attributable to cytomegalovirus infection. (2) Tumors consisted of primary lymphoma of the brain in 3 patients and meningeal invasion by systemic lymphoma in 4. (3) Vascular complications included nonbacterial thrombotic endocarditis in 2 patients and cerebral hemorrhages in the setting of thrombocytopenia in 3. (4) Undiagnosed central nervous system problems were evidenced as focal brain lesions in 3 patients and self-limiting aseptic meningitis in 4. Peripheral neuropathy occurred in 8 patients.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Evoked potential latency change with age suggests differential aging of primary somatosensory cortex.

The latencies of the first two cortical peaks in the somatosensory evoked potential were examined in subjects of various ages. Recent work on specialization of primary sensory cortex in primates implicates the cortical site of origin of the second cortical peak, P25, in the selective sensory losses of old age. The latency of the P25 peak changed significantly with age. The latency of the preceeding N20 peak, also of cortical origin but originating from a different site, showed no significant age-related change. Sex differences were present in both N20 and P25 latencies but were independent of the age effect in the latter. Our results provide electrophysiological evidence for differential aging of anatomically separate areas of somatosensory cortex.

Adult↗