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Biomedical subjects

R C Baldwin

Publications and source records attributed to R C Baldwin.

At least 37 records · Page 2Linked to original sources
PubMed1997

1997 IPA/Bayer Research Awards in Psychogeriatrics. Subcortical hyperintensities in late-life depression: acute response to treatment and neuropsychological impairment.

Subcortical hyperintensities are easily visualized areas of signal abnormality that are seen on T2-weighted magnetic resonance imaging (MRI). Characteristically they occur in the white matter of the brain and are more common in elderly people. In depression, little is known of the clinical significance of subcortical hyperintensities or their contribution to the prognosis. Fifty-eight consecutive patients with DSM-III-R depression and an age range of 65 to 85 years were prospectively collected from an old-age psychiatry service. Response to treatment was assessed with a clinical global outcome measure. A neuropsychology battery was completed on all patients after treatment. Forty-four patients completed MRI scanning. The scans were scored using a regional rating system for hyperintensities. Forty-eight percent of patients had a favorable response to treatment on the clinical global outcome scale. Poor outcome was associated with female sex (p = .07), poor physical health (p = .040), diabetes (p = .018), psychosis (p = .026), and an early age at onset of first episode of depression (p = .036). Even after adjustment for confounding effects, there were significant neuropsychological associations with the regional hyperintensities. Distribution in the periventricular area correlated with delayed recall after distraction (p = .025), and punctate lesions in the basal ganglia correlated with impaired category production (p = .020). Pontine reticular formation hyperintensities were related to impaired psychomotor speed (p = .04). Location in the frontal deep-white matter (p = .024), basal ganglia (p = .03), and pontine reticular formation (p = .02) was associated with a poor acute response to treatment. However, the response to treatment was not related to total cerebral white-matter hyperintensity load. A logistic regression equation included all the significant prognostic features and found four independent predictors of poor outcome: More than five punctate lesions of the basal ganglia, diabetes, lower mean arterial pressure, and hyperintensity of the pontine reticular formation significantly predicted outcome. These four factors correctly predicted 95.6% of patients with a poor outcome and 85.7% with a favorable outcome. In late-life depression, subcortical hyperintensities are common. Lesions in the cerebral white matter are predominantly associated with memory disturbance, and those in deeper infratentorial areas, with psychomotor slowing and executive deficits. Total white-matter load has no prognostic value, and although some subcortical regions are associated with poor response, individually they have little specificity. However, a combination of involvement in three areas (basal ganglia, pons, and frontal lobe) is clinically relevant and predicts outcome with great accuracy (91%). Patients with lesions in the basal ganglia and deep white matter had an especially poor response to pharmacotherapy.

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PubMed1997

Prognosis and outcome studies in late-life depression.

This article reviews our current understanding of the outcome of depression in older people and factors predictive of outcome. Research into neurobiological factors that may be of relevance to outcome is touched on, with suggestions for improving outcome.

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PubMed1995

Antidepressants in geriatric depression: what difference have they made?

This article reviews the evidence that antidepressants have improved the prognosis of geriatric depression. It examines studies carried out in the acute, continuation, and maintenance stages of treatment. Naturalistic studies carried out after the introduction of electroconvulsive therapy indicate that about one quarter of patients with major depression in later life remain symptom-free, approximately one third experience at least one relapse but with further recovery, and the remainder have residual symptoms. In about 10% of all cases, depressive symptoms remain severe and intractable. These proportions appear to have altered little since tricyclic antidepressants became available, although recent research into drug prophylaxis suggests that better outcomes may be possible. The article reviews some of the methodological problems that research workers must address. The role of newer antidepressants in prognosis is also discussed.

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PubMed1995

Depression in later life. A comparison of symptoms and risk factors in early and late onset cases.

BACKGROUND: Depression in later life is often thought to differ from that at other times of adulthood. The evidence for this is controversial but is important to any proposed organic model of depression in the elderly. Here, early- and late-onset depressions in later life are compared. METHOD: Fifty-seven depressed patients with a mean age of 74 were studied, 21 with an early onset (aged 59 or less) and 36 with a late onset. All were suffering from major depression according to DSM-III-R. The measures at entry included severity and symptoms, cognitive function, antecedent life events, physical health and vascular risk factors and/or vascular disease. We also recorded any family history of mood disorders, as well as the course of illness. RESULTS: The anxiety item scores of the Hamilton Depression Rating Scale were significantly higher in those with an early onset, but otherwise symptoms differed little. Heritability was greater in the early-onset group. There was a striking association of vascular disease and/or risk with late-onset patients. CONCLUSIONS: Vascular disease is associated with late-onset depression. This is consistent with the hypothesis that depression in later life is a more 'biological' disorder.

Adult↗
PubMed1994

External reflection FTIR of peptide monolayer films in situ at the air/water interface: experimental design, spectra-structure correlations, and effects of hydrogen-deuterium exchange.

A Fourier transform infrared spectrometer has been interfaced with a surface balance and a new external reflection infrared sampling accessory, which permits the acquisition of spectra from protein monolayers in situ at the air/water interface. The accessory, a sample shuttle that permits the collection of spectra in alternating fashion from sample and background troughs, reduces interference from water vapor rotation-vibration bands in the amide I and amide II regions of protein spectra (1520-1690 cm-1) by nearly an order of magnitude. Residual interference from water vapor absorbance ranges from 50 to 200 microabsorbance units. The performance of the device is demonstrated through spectra of synthetic peptides designed to adopt alpha-helical, antiparallel beta-sheet, mixed beta-sheet/beta-turn, and unordered conformations at the air/water interface. The extent of exchange on the surface can be monitored from the relative intensities of the amide II and amide I modes. Hydrogen-deuterium exchange may lower the amide I frequency by as much as 11-12 cm-1 for helical secondary structures. This shifts the vibrational mode into a region normally associated with unordered structures and leads to uncertainties in the application of algorithms commonly used for determination of secondary structure from amide I contours of proteins in D2O solution.

Air↗
PubMed1994

Screening for anxiety and depression in elderly medical outpatients.

In a study of 45 consecutive new outpatients at geriatric medicine clinics, 17.8% were diagnosed as depressed and 2.2% as anxious using the Geriatric Mental Status Schedule. Of two screening instruments, the Geriatric Depression Scale (GDS), in either 30-item or 15-item version, performed well and the depression sub-scale of Goldberg and Bridges' screening questionnaire for depression and anxiety in medical settings was adequate. The anxiety sub-scale of the latter was poor. Detection by geriatricians of depression and anxiety disorders was poor. It is recommended that a short screening instrument for the detection of depression, such as the GDS, be incorporated into the clinic setting. As yet there is no satisfactory screening questionnaire for detecting anxiety disorders.

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PubMed1993

Depression in old age. A reconsideration of cerebral disease in relation to outcome.

In a prospective study, 32 patients with depressed mood and cerebral pathology were compared over one year with 66 depressed patients who were cerebrally intact. The hypothesis that the former would have a poorer outcome for depression was not confirmed, although the group with cerebral pathology had a significantly higher than expected death rate. Prognostic factors were identified only for the cerebrally intact group. Those who had major depression were more likely than those with minor depression to be given physical treatments, irrespective of which group they belonged to.

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PubMed1993

Diffusion versus iontophoresis in the transport of gentamicin in the burned rabbit ear model.

This experimental study demonstrates that iontophoresis can be used to transport biologically active gentamicin into auricular cartilage. Fifty female New Zealand White rabbits were divided into three groups: live controls with unburned ears, live animals with burn-injured ears (deep or partial-thickness), and euthanized animals with unburned ears. Each group was then divided into subgroups that received gentamicin transported by iontophoresis or diffusion. In ears subjected to iontophoresis, adequate gentamicin activity could be demonstrated only in the cartilage of euthanized animals with unburned ears and live animals with full-thickness burned ears. Diffusion did not transport a detectable level of gentamicin in any instance. Diffusion is ineffective in the transport of gentamicin and should not be used as a primary method of treatment for ear chondritis. Iontophoresis did not transport active gentamicin across partial-thickness burns, presumably because the migrating antibiotic molecules were dispersed throughout the body by the circulation. However, if the circulation is destroyed, as in a full-thickness burn, iontophoresis can move the biologically active gentamicin into the cartilage.

Animals↗
PubMed1988

Delusional and non-delusional depression in late life. Evidence for distinct subtypes.

The study tests the hypothesis that delusional and non-delusional depressive illnesses are distinct entities in late life. Two groups of 24 patients with late-onset depression, one with and one without delusions, were compared retrospectively. At the index admission, deluded patients were significantly more depressed, were in hospital for longer, responded poorly to antidepressants alone and required more physical treatments, especially ECT and major tranquillisers. Although illness severity was a major factor accounting for these differences, the finding that only the deluded group experienced delusional relapses suggests an underlying intrinsic susceptibility. The discharge status was similar for both groups, as were relapse rates over 48 months and the clinical course of depressive symptoms over 42-104 months. The findings are consistent with studies of younger patients which point to a distinction between these two types of depression, but not with recent work suggesting a very poor prognosis for delusional depression in late life.

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PubMed1986

The prognosis of depression in old age.

The initial features and progress of depressive symptomatology over 42 to 104 months are presented for 100 elderly patients admitted with severe, non-neurotic depressive states; none had experienced a previous hypomanic episode. Sixty per cent either remained well throughout or had further episodes followed by full recovery; only 7% suffered continuous depressive symptoms. Of potential prognostic factors, only male sex and poor physical health, both at presentation and developing subsequently, were associated with poorer outcomes. The view is supported that treatment with well established methods achieves worthwhile and sustained improvement for most patients.

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PubMed1985

Acute toxicity, subchronic dermal toxicity, and delayed contact sensitization evaluations of dicyclopentenyloxyethyl methacrylate in rabbits and guinea pigs.

The subchronic dermal toxicity of dicyclopentenyloxethyl methacrylate (DPOMA) was evaluated in young adult New Zealand White rabbits, and its potential to produce delayed contact sensitization was evaluated in Harley guinea pigs by a modified Buehler's closed patch technique. In addition, studies were conducted to evaluate the acute systemic toxicity of DPOMA in rats (oral) and rabbits (dermal), and its eye and skin irritancy in rabbits. In the subchronic dermal toxicity study, 4 groups of rabbits were treated percutaneously with DPOMA at 0 (acetone), 10, 107, and 1067 (undiluted) mg/kg X day in a volume of 1 ml/kg, over a 4-wk period. The application sites were unoccluded. No deaths occurred, and no signs of systemic toxicity were observed. No treatment-related effects were seen on body weights, hematology, clinical chemistry, urinalysis, organ weights, or histopathology (except the treated skin). The only treatment-related effect was slight to moderate skin irritation in the mid- and high-dose groups. The severity of skin irritaton was dependent on the number of applications and the concentration of DPOMA. Maximal skin irritation occurred after 1 wk. No skin irritation was seen in the control and low-dose group. In the DCS study, guinea pigs received 6 induction doses of 0.5 ml 100% DPOMA and were challenged with 0.5 ml of 50% (w/v) DPOMA in acetone 2 wk after the last induction treatment. No erythema or edema was observed in any of the challenged guinea pigs in either the treated and control groups. These acute toxicity studies indicate that DPOMA is practically nontoxic by a single exposure via both oral and dermal routes (the oral LD50 in rat and dermal LD50 in rabbits were greater than 5.0 g/kg body weight), slightly irritating to the skin, and inconsequentially irritating to the eyes. The no-observed-effect level (NOEL) for systemic toxicity of DPOMA applied repeatedly to rabbits skin is at least 1067 mg/kg X d. DPOMA is not a strong or moderate skin sensitizer in guinea pigs.

Acrylates↗
PubMed1983

Kathon biocide: manifestation of delayed contact dermatitis in guinea pigs is dependent on the concentration for induction and challenge.

The potential of Kathon biocide, an aqueous solution containing, as active ingredients (a.i.), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (14.4% a.i.), to produce delayed contact dermatitis, a sensitization response, was evaluated in outbred Hartley guinea pigs by a modified Buehler's occluded epicutaneous patch technique. The relationship of the response as a function of induction/elicitation concentrations was investigated. Groups of guinea pigs received 9 induction doses of the biocide, 3 times a week, at concentrations ranging from 25-2000 ppm a.i. These guinea pigs were challenged with the biocide at concentrations ranging from 20-2000 ppm a.i., and the application sites were scored for erythema 24 and 48 h after the challenge. The incidence of delayed contact dermatitis in induced guinea pigs was dependent on both the induction and challenge concentrations. The EC50 (concentration at which delayed contact dermatitis was seen in 50% of the population) for induction at a challenge concentration of 2000 ppm a.i., a nonirritating concentration, was estimated to be 88 ppm a.i. with a slope of 3.47 probits/unit log concentration. The EC50 for elicitation at an induction concentration of 1000 ppm a.i. was estimated to be 429 ppm a.i. with a slope of 2.74 probits/unit log concentration. These data demonstrate that for Kathon biocide, there is an induction/elicitation concentration dependency for delayed contact dermatitis response, and there is a "no response concentration" zone where the biocide can be used without concern for clinically significant delayed contact dermatitis. In comparison with a previous study, these data also suggest that the number of induction doses may be an important factor in demonstrating the sensitization potential of a chemical.

Animals↗