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Biomedical subjects

K Jones

Publications and source records attributed to K Jones.

At least 19 recordsLinked to original sources
PubMed1992

Clinical and histopathologic changes in the host cornea after epikeratoplasty for keratoconus.

Five consecutive patients underwent epikeratoplasty for keratoconus. Postoperatively, four patients had poor visual acuity (average, 20/200) secondary to folds in Descemet's membrane and interface scarring. Two underwent penetrating keratoplasty eight months later. Histopathologic examination of the host corneas and the overlying lenticules disclosed epithelial irregularity and subepithelial fibrosis. The host corneas showed folds in Descemet's membrane and focal posterior stromal fibrosis. Electron microscopy disclosed breaks in Bowman's membrane with irregular collagen, posterior aggregates of amorphous material, and focal endothelial degeneration. The fifth patient had graft ulceration and vascularization that required removal of the lenticule. She underwent a penetrating keratoplasty five months later and histopathologic examination demonstrated persistent folds in Descemet's membrane. Immunostaining of specimens from three cases disclosed a reduced expression of sulfated epitopes of keratan sulfate and an increase in sulfated dermatan sulfate in the lenticule and host corneal tissues. These alterations in stromal proteoglycans are characteristic of stromal scars and keratoconus and provide evidence of pathologic processes in the graft tissue. Because of potential complications, epikeratoplasty should be considered only for those patients who are unsuitable candidates for contact lenses or penetrating keratoplasty.

Adult↗
PubMed1992

Prospective multicentre study of pregnancy outcome after lithium exposure during first trimester.

Lithium carbonate is an effective drug for prophylaxis and treatment of major affective disorders. In-utero exposure to lithium during the first trimester of pregnancy might be associated with an increased risk of cardiac malformations, especially the rare Ebstein's anomaly. We prospectively recruited and followed 148 women (mean age 30 years, SD 5 range 15-40) using lithium during the first trimester of pregnancy, who consulted four teratogen information centres in the USA and Canada. Pregnancy outcome was compared with that of controls matched for maternal age. We had complete follow-up of pregnancy outcome in 138 of 148 patients recruited. In the other 10, fetal echocardiograms were available but postnatal follow-up was not done. Mean daily dose of lithium was 927 mg (SD 340). Rates of major congenital malformations did not differ between the lithium (2.8%) and control (2.4%) groups. 1 patient in the lithium group chose to terminate pregnancy after Ebstein's anomaly was detected by a prenatal echocardiogram. There was 1 ventricular septal defect in the controls. Birthweight was significantly higher in the lithium-exposed infants than in the controls despite identical gestational ages (3475 [660] g vs 3383 [566] g, p = 0.02). The true difference in birthweight might have been even larger, since significantly more women using lithium than controls were cigarette smokers (31.8% vs 15.5%, p = 0.002). These results indicate that lithium is not an important human teratogen. Women with major affective disorders who wish to have children may continue lithium therapy, provided that adequate screening tests, including level II ultrasound and fetal echocardiography, are done.

Abnormalities, Drug-Induced↗
PubMed1992

Inhibition of protein kinase C by ether-linked lipids is not correlated with their antineoplastic activity on WEHI-3B and R6X-B15 cells.

To test the hypothesis that the action of antineoplastic ether-linked lipids in leukemic cells is associated with their ability to inhibit protein kinase C (PKC), we have compared the effects of two ether-linked lipids, 1-O-hexadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET16-OCH3-GPC) and 1-O-hexadecyl-2-O-methyl-sn-glycero-3-(S-beta-D-1'- thioglucopyranosyl)-sn-glycerol (ET16-OCH3-beta-thio-Glc), on two different leukemic cell lines (WEHI-3B and R6X-B15). ET16-OCH3-GPC killed WEHI-3B cells with an EC50 value of 2.5 microM, whereas it was far less effective against R6X-B15 cells (EC50 = 40 microM). In contrast, the beta anomer of ET16-OCH3-beta-thio-Glc did not kill either cell line at concentrations up to 40 microM. Both ET16-OCH3-GPC and ET16-OCH3-thio-Glc inhibited 12-O-tetradecanoylphorbol 12,13-dibutyrate (TPA)-induced PKC translocation in both WEHI-3B and R6X-B15 cells. When WEHI-3B cells were first exposed to TPA, and then to ET16-OCH3-GPC, no significant decrease in PKC activity in the particulate fraction was noticed. When, however, the cells were first exposed to ET16-OCH3-GPC and then to TPA, the enzyme activity in the particulate fraction was decreased by 20-30%. A phorbol dibutyrate binding assay showed that the decrease in membrane-associated PKC activity and the increase in cytosolic PKC activity did not result from impeded enzyme translocation. These results suggest that the similar PKC inhibitory potency of ET16-OCH3-GPC and ET16-OCH3-beta-thio-Glc: (a) is not correlated with the widely different cytotoxicities of these agents and (b) is probably due to interference with the binding of diacylglycerol/phosphatidylserine or TPA to PKC. Taken together, these results suggest that the ether-linked lipids compete with diacylglycerol/phosphatidylserine or TPA for binding sites on PKC required for enzyme activation.

Antineoplastic Agents↗
PubMed1992

Comparative analysis of computed tomographic and magnetic resonance imaging scans in Alzheimer patients and controls.

Ten patients with Alzheimer's disease underwent computed tomography and magnetic resonance imaging at the same point in time. The mean Mini-Mental State examination score of the patients was 23, indicating that they were mildly impaired. Ten age-equivalent controls also obtained computed tomographic and magnetic resonance imaging scans. A semiautomated computer program analyzed nine comparable regions of interest on each set of scans. When regions of interest from both types of scans were combined in the same discriminant function analysis, the first two variables selected were from the magnetic resonance imaging data set, and they significantly differentiated 95% of the patients and controls.

Aged↗
PubMed1992

Ocular-chondrodysplasia in labrador retriever dogs: a morphometric and electron microscopical analysis.

Ocular-chondrodysplasia in Labrador Retriever dogs is characterized by short-limbed dwarfism and ocular abnormalities. The purposes of the present study were to develop morphological criteria to define the matrix and/or chondrocytic abnormalities associated with this chondrodysplasia, and to test the hypothesis that ineffective matrix-directed cellular swelling was associated with the decreased longitudinal bone growth in these animals. The proximal and distal radial growth plates were collected from four affected animals of the same litter. Stereological techniques were used to analyze both cellular shapes and cellular volume changes in the hypertrophic zone. The pathological changes seen in these growth plates varied between animals and included disorganization of cellular columns with abnormal extent of calcification. Chondrocytes of all zones contained two types of abnormal cellular inclusions classified as light and dark, based on the intensity of eosinophilic staining. Both types of inclusions contained material that resembled the surrounding extracellular matrix, varying only in the apparent hydration of the contents. It could be demonstrated that light inclusions were located in the peripheral cytoplasm and connected to the extracellular matrix through narrow channels. By contrast, dark inclusions were membrane bound and perinuclear. Chondrocytes with multiple, large inclusions appeared to be undergoing degenerative changes. Although the final volume achieved by hypertrophic chondrocytes was consistent with that of normal growth plates, there was a high level of variability of chondrocytic shape and evidence of premature cellular condensation in the maturation zone. The severity of the dwarfism correlated both with the extent of chondrocytic changes and the severity of the ocular lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Unrestricted principal components analysis of brain electrical activity: issues of data dimensionality, artifact, and utility.

Principal components analysis (PCA) was performed on the 1536 spectral and 2944 evoked potential (EP) variables generated by neurophysiologic paradigms including flash VER, click AER, and eyes open and closed spectral EEG from 202 healthy subjects aged 30 to 80. In each case data dimensionality of 1500 to 3000 was substantially reduced using PCA by magnitudes of 20 to over 200. Just 20 PCA factors accounted for 70% to 85% of the variance. Visual inspection of the topographic distribution of factor loading scores revealed complex loadings across multiple data dimensions (time-space and frequency-space). Forty-two non-artifactual factors were successful in classifying age, gender, and a separate group of 60 demented patients by linear discriminant analysis. Discrimination of age and gender primarily involved EP derived factors, whereas dementia primarily involved EEG derived factors. Thirty-eight artifactual factors were identified which, alone, could not discriminate age but were relatively successful in discriminating gender and dementia. The need to parsimoniously develop real neurophysiologic measures and to objectively exclude artifact are discussed. Unrestricted PCA is suggested as a step in this direction.

Adult↗
PubMed1992

Spermine dialdehyde, a novel ex vivo purging agent for both allogenic and autologous bone marrow transplantations.

The use of ex vivo purging agents has shown to be beneficial for both allogeneic and autologous bone marrow transplantations. We have shown previously that spermine dialdehyde (SDA), an oxidized product of spermine, when used in phosphate-buffered saline (PBS) preferentially inhibits T-cell proliferation while sparing myeloid cells. Lethally irradiated mice were rescued by reconstitution with SDA-treated allogeneic marrow and showed no sign of graft-vs-host disease (GVHD). In this paper, we show by HPLC analysis that SDA degraded rapidly in PBS but remained intact in saline. Administered in saline, SDA was more inhibitory on leukemic cell lines than normal myeloid or T-cells. Lethally irradiated mice receiving a syngeneic bone marrow leukemic cell mixture treated ex vivo with SDA in saline did not manifest leukemia. Thus, the preferential inhibitory effect of SDA and its degraded products in different buffers suggest that SDA could act as a novel purging agent for both allogeneic and autologous bone marrow transplantations.

Acrolein↗
PubMed1992

A conservative approach to the management of otitis media with effusion in cleft palate children.

Otitis media with effusion (OME) is almost universal in children born with a cleft palate. Early placement of a ventilation tube to alleviate hearing problems is common. A retrospective study has been carried out to assess whether the practice of tube placement only for definite clinical indications is successful in terms of subsequent hearing levels and speech and language development. This was assessed by a case note review, analysis of speech therapy data and by means of a special follow-up clinic. There was no difference in speech development between those treated with tube insertion for OME and those untreated. Audiological thresholds were worse in the treated group. A similar number in each group required regular speech therapy. More abnormal otological findings were present at follow up in those who had tubes inserted, some of these were directly attributable to the presence of tubes. A conservative management of OME in cleft palate children, with tube insertion for only definite clinical indications, is an appropriate management, and will lead to fewer otological complications of tube insertion.

Adolescent↗
PubMed1992

Immunization status of casualty attenders: risk factors for non-compliance and attitudes to 'on the spot' immunization.

Outbreaks of vaccine preventable infections have focused attention on 'missed opportunities' for immunizing children. The immunization status of 520 consecutive children attending Casualty during a 10 day period was studied. Only 70% of children had received their diphtheria, tetanus, pertussis (DTP) and poliomyelitis immunization at the appropriate time, 13% had completed the schedule later than recommended and 17% had immunizations overdue by 4 weeks or more. For measles (mumps/rubella) vaccine (MM or MMR) 75% were up to date, 10% were given late and 15% were overdue. A subset of 171 families was interviewed to evaluate factors affecting compliance. Families possessing a Social Security 'Health Care Card', whose father was unemployed, who spoke poor English or who had lived in Australia for 5 years or less were significantly more likely (P < 0.02) to be inadequately immunized. There were 84 children whose immunization was overdue and who were well enough to be immunized. The parents of 70 (83%) of these 84 said that they would agree to 'on the spot' immunization if it were available; 14 (17%) parents refused, the commonest reason for refusal being that the parents felt that the child was too sick at the time to be immunized.

Child↗
PubMed1992

Factor structure and reliability of the Reasons for Living Inventory.

This study examined the factor structure and internal consistency reliability of the Reasons for Living Inventory for 275 college students. Principal components factor analysis with varimax rotation extracted five factors, based on the scree test. The derived factors were identical with the inventory's subscales, except for the Fear of Suicide subscale and Social Disapproval subscale items loading on the same factor. Significant gender differences were obtained on the Responsibility to Family, the Fear of Suicide, and the Moral Objections subscales. The pattern of subscale correlations was similar for the subsamples. The coefficients alpha for the subscales ranged from moderate to high.

Adult↗
PubMed1992

Reliability and validity of the Cognitive Slippage Scale in two populations.

Analyses of responses from a clinical sample of 120 patients (primarily schizophrenics) and from 158 college students to the Cognitive Slippage Scale, a scale designed by Miers and Raulin to identify speech deficits and confused thinking in schizophrenic and schizotypal personality disorders showed high internal reliability; Cronbach's coefficients alpha were .89 and .86 in the clinical and college student samples, respectively. The mean scale scores significantly differentiated the two samples. Also, change scores over 4 wk. showed adequate stability for both samples. Item analysis indicated Items 11, 20, 21, and 28 may not reliably discriminate between schizophrenic and college student samples. Over-all, these preliminary results are consistent with the reliability and validity of the scale.

Adult↗
PubMed1992

Schoolteachers' perceptions and knowledge of asthma in primary schoolchildren.

Schoolteachers are known to be concerned about asthma in their pupils but their opinions about the best method of addressing this concern have not previously been investigated. Eleven headteachers and 76 class teachers from 11 primary schools in the Southampton area--eight from the state sector and three private day schools--completed questionnaires. These inquired about the organization of care for asthmatic pupils, the teachers' knowledge, concerns and training regarding the disease, and their perceptions of the need for and source of further education for teachers about asthma. All 10 National Health Service school health services in the Wessex region and 16 teacher training colleges responded to questions about their provision of such education for teachers. The results demonstrated that asthma care in the 11 schools was generally disorganized, with the responsibility for keeping and administering inhalers falling on the school secretary in seven of the schools. All but two of the 11 headteachers and 89% of the class teachers were concerned about asthma, primarily in managing emergencies. Levels of knowledge were low, particularly regarding exercise, and education about asthma was almost non-existent. The great majority of class teachers (86%) wanted more information about asthma and most (67%) looked to the school health services to provide this. None of the school health services in Wessex and only one teacher training college had any planned education about asthma for teachers. Clearly, schools need to receive more information about asthma, both to enable them to cope more ably with their asthmatic pupils and to allay the anxieties of teachers.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1992

Experimental hydroxyapatite cement cranioplasty.

Hydroxyapatite cement is a calcium phosphate-based material that when mixed with water forms a dense paste that sets within 15 minutes and isothermically converts in vivo to a microporous hydroxyapatite implant. This cement was used to reconstruct bilateral 2.5-cm-diameter full-thickness critical-sized parietal skull defects in six cats. One side was reconstructed with 100 percent hydroxyapatite cement, and the other with a mixture of 50 percent hydroxyapatite cement and 50 percent ground autogenous bone by weight. These animals were sacrificed at 6 and 12 months after implantation. Positive and negative controls also were prepared. The anatomic contour of the soft tissue overlying all hydroxyapatite cement implants was well maintained, there were no wound infections or structural failures, and the implants were well tolerated histologically. None of the negative (unreconstructed) control defects was completely filled with repair bone, and all positive (methyl methacrylate) controls demonstrated foreign-body giant-cell formation and fibrous encapsulation of the implants. Examination of decalcified and undecalcified sections revealed progressive but variable replacement of the cement by new bone and soft tissue without a change in the shape or volume of the hydroxyapatite cement-reconstructed areas. New bone comprised 77.3 and 64.7 percent of the tissue replacing the hydroxyapatite cement and hydroxyapatite cement-bone implants, respectively. Replacement of the hydroxyapatite cement implants by new bone is postulated to occur by a combination of osteoconduction and implant resorption. These results indicate that further experimental research leading to the possible application of hydroxyapatite cement for full-thickness calvarial defect reconstruction in humans is warranted.

Animals↗