Biomedical subjects

M Harrow

Publications and source records attributed to M Harrow.

At least 19 recordsLinked to original sources

PubMed2001

Auditory working memory in HIV-1 infection.

We evaluated auditory working memory in 41 HIV-seropositive (HIV+) and 37 HIV-seronegative (HIV-) male drug users, employing a modified version of the Letter-Number Span Task developed by Gold and colleagues. We added a control condition to the standard task in order to evaluate more directly the contribution of the processing component to the working memory deficits with the effects of storage demands minimized. HIV+ subjects performed significantly more poorly compared to controls on an index of working memory processing derived from raw scores obtained under the two testing conditions. These findings are consistent with our previous reports that HIV-related working memory deficits are evident across multiple informational domains; further, the deficit appears to involve multiple-component functions of working memory. Converging findings from recent working memory studies and from primate and neuroimaging investigations suggest that functional abnormalities of prefrontal cortex should receive greater emphasis in models of neurocognitive aspects of HIV-1 infection, which have typically emphasized "subcortical" deficits.

AIDS Dementia Complex↗

PubMed2001

Longitudinal assessment of negative symptoms in schizophrenia/schizoaffective patients, other psychotic patients, and depressed patients.

This study assessed differences in negative symptom presentation between schizophrenia/schizoaffective, other psychotic, and depressed patients over a 10-year followup period. One hundred fifty individuals with schizophrenia or schizoaffective disorders (SZ/SZAF), other psychotic disorders (OP), and depressed patients (DP) were assessed at index hospitalization, then reassessed at 4.5-year, 7.5-year, and 10-year followups. SZ/SZAF patients significantly differed from DP patients in frequency and persistence of negative symptoms but were not significantly different from the OP group. Negative symptoms were not associated with depression in any diagnostic group. Dosage, but not simple use, of conventional antipsychotic medications was related to severity of symptoms in the SZ/SZAF group. Although negative symptoms were typically most severe and most common in the SZ/SZAF subjects in comparison to the DP patients, there were few statistically significant differences in the phenomenology of negative symptoms between the OP and SZ/SZAF groups. The data are consistent with a model that identifies negative symptoms as common to mental illnesses generally, with particularly high rates in psychotic illnesses.

Adult↗

PubMed2001

Risk for bipolar illness in patients initially hospitalized for unipolar depression.

OBJECTIVE: To assess the risk for subsequent development of mania or hypomania, the authors conducted a 15-year prospective follow-up study of a large, young cohort of patients originally hospitalized for unipolar major depression. METHOD: Patients who were hospitalized for unipolar major depression (N=74; mean age=23.0 years, SD=3.8) were assessed prospectively as inpatients and then followed up five times over 15 years, at approximately 2, 5, 8, 11, and 15 years after discharge. Manic or hypomanic episodes, medications, and rehospitalizations were determined by standardized assessments at each follow-up. Polarity conversions were evaluated by survival analyses. RESULTS: By the 15-year follow-up, 27% of the study group had developed one or more distinct periods of hypomania, while another 19% had at least one episode of full bipolar I mania. Depressed patients with psychosis at the index depressive episode were significantly more likely than nonpsychotic patients to demonstrate subsequent mania or hypomania at follow-up. Those with family histories of bipolar illness showed a nonsignificantly higher rate of switching to mania or hypomania. Spontaneous and antidepressant-associated manias did not differ in frequency. Fewer than one-half of the patients who showed an eventual bipolar course had received prescriptions for mood stabilizers in any follow-up year. CONCLUSIONS: Young depressed inpatients with psychotic features may be at especially high risk for eventually developing mania. The probability for developing a bipolar spectrum disorder increases in linear fashion for patients at risk for polarity conversion during the first 10-15 years after an index depressive episode.

Adult↗

PubMed2000

A prospective longitudinal 10-year study of schizophrenia's three major factors and depression.

This study investigated the nature, independence, and stability of schizophrenia's syndrome factors and depression at 2, 4.5, 7.5 and 10 years post-index hospitalization. At the four follow-ups, 71 patients (48 with schizophrenia and 23 with schizoaffective disorder) were assessed for symptoms hypothesized to constitute the reality distortion, disorganized, and negative factors of schizophrenia. At the last three follow-ups, the patients were also assessed for symptoms of depression. Factor analyses of schizophrenia symptoms revealed more than three syndrome factors at each follow-up. Longitudinally, reality distortion was a stable and relatively independent factor. The negative syndrome was independent but was bifurcated into two dimensions, interpreted as social/emotional withdrawal and diminished movement/expressiveness. Although signs of disorganization were not unified or independent early in schizophrenia's course, speech/thought disorder, disorganized affect, and poverty of speech content coalesced to form a disorganization factor by the 7.5-year follow-up. When depressive symptoms were added to the analyses, depression constituted an independent and stable dimension of schizophrenia over time. Each schizophrenia factor demonstrated a unique longitudinal course. Courses included stable symptom consistency (reality distortion), evolving symptom convergence (disorganization), and recurrent bifurcation and symptom instability (the negative syndrome).

Adult↗

PubMed2000

The water quality of the River Thames at a rural site downstream of Oxford

Water quality information is presented for the River Thames 34 km downstream of the market town of Oxford in Oxfordshire to provide an overview of the hydrochemical functioning of a major agriculturally impacted river entering the North Sea. The data, which cover the period from the spring of 1997 to the spring of 1999, relate to three types of data. These types are: (1) weekly spot sampling for determination of major, minor and trace elements, pH, alkalinity and herbicides; (2) tri-weekly spot sampling for pH, alkalinity and dissolved silicon; and (3) continuous measurements of pH and dissolved oxygen. Calcium and bicarbonate provide, respectively, the dominant cation and anion in solution and their compositions remain relatively constant through time, irrespective of flow levels. In contrast, many determinands show seasonally related fluctuations. Concentrations for most of the major anions, sodium, potassium as well as soluble reactive phosphorus and several soluble trace elements such as boron, antimony, arsenic and molybdenum decrease as flow increases. A reverse pattern is observed for nitrate, some herbicides and trace elements associated with particulate phases: concentrations increase with increasing flow. These patterns reflect the influence of: (1) a calcium carbonate rich groundwater system which provides the main stream flow component; (2) dilution of point source pollutant inputs associated with sewage and possibly light industry at high flows for several major, nutrient and trace elements; (3) enhanced nitrate and herbicide runoff from agricultural land at high flows; (4) enhanced microparticulate trace metal levels associated with increased suspended sediment loads at high flows; and (5) biological processes which affect pH, dissolved silicon, dissolved carbon dioxide and dissolved oxygen levels. An examination of soluble reactive phosphorus (SRP) and boron relationships reveals a reduction in concentrations for SRP associated possibly with phosphorus removal from a major sewage treatment works on an upstream tributary of the Thames, the Thame.

Journal Article↗

PubMed2000

The water quality of a tributary of the Thames, the Pang, southern England.

The water quality of a tributary of the Thames, the Pang, draining a rural part of the Thames basin is described and related to the influences of inputs from farming activity and groundwater from the underlying chalk aquifer as modified by biological within-stream processes. The groundwater inputs ensures that the waters are calcium and bicarbonate bearing and have relatively uniform concentrations. Agricultural inputs result in enhanced levels of nutrients, nitrate and soluble reactive phosphorus (SRP) in particular. For nitrate, the concentrations are higher during the winter months due to increased surface runoff. In contrast, SRP shows a more erratic behaviour with higher concentrations occurring during the early storm hydrograph rise following summer baseflow recession. Within the stream, biological activity results in: (a) marked diurnal fluctuations in the dissolved levels of carbon dioxide and oxygen; (b) a strong seasonal pattern in chlorophyll a levels; and (c) dissolved silica concentration reductions during the early spring period. Carbon dioxide levels are particularly high in the groundwater (typically approximately 60 times the atmospheric value) as observed at a spring discharge. However, within the stream, considerable degassing occurs although values remain an order of magnitude above atmospheric pressure. The findings are discussed in the context of the water quality functioning of agriculturally and sewage impacted southern eastern UK rivers. For example, the work shows that unlike for riverine systems with point sewage discharges or limited groundwater storage, there is a very poor link between chemical concentrations and flow even for components such as SRP and boron which are often connected to sewage discharges.

Agriculture↗

PubMed2000

The water quality of the River Kennet: initial observations on a lowland chalk stream impacted by sewage inputs and phosphorus remediation.

The water quality of seven sites on the upper reaches of the River Kennet round the market town of Marlborough is described and related to the introduction of phosphorus treatment of effluent from Marlborough sewage treatment works (STW). The River Kennet is mainly groundwater-fed from a Cretaceous chalk aquifer and hence the river water is calcium- and bicarbonate-bearing and has a relatively constant composition of many major water quality determinants. In-stream biological activity gives rise to marked diurnal fluctuations in pH (of approx. 0.8 units). Dissolved carbon dioxide and dissolved oxygen also show marked diurnal fluctuations. Dissolved carbon dioxide varies from approximately 10 to 70 times atmospheric pressure, indicating net release of carbon dioxide and the dominance of heterotrophic (respiratory) processes over autotrophic processes (photosynthesis). Much of the excess carbon dioxide is probably associated with carbon dioxide laden groundwater inputs and the relatively short within-stream residence times ensures only limited degassing to the atmosphere. Diurnal fluctuations in dissolved oxygen vary from approximately 20% to 200% saturation. For both dissolved carbon dioxide and dissolved oxygen, the amplitude of fluctuations is much lower during the winter period, when biological activity is at its lowest. The concentrations of soluble reactive phosphorus (SRP), total phosphorus (TP) and boron increase markedly just downstream of the sewage works as a result of this point source input. These concentrations slowly decline further downstream as additional groundwater inputs dilute the effluent further. The introduction of chemical treatment of sewage effluent for phosphorus reduction at Marlborough STW resulted in a marked decrease in within-river SRP and TP concentrations to levels approximately the same as those upstream of the STW. A comparison of SRP and boron concentrations reveals a reduction in in-stream SRP concentrations by approximately 75% following effluent treatment. In terms of within-river processes controlling in-stream phosphorus concentrations, previous studies have indicated that one potentially important mechanism within calcium bicarbonate bearing rivers may be related to co-precipitation of phosphorus with calcium carbonate (calcite). The present study shows that the waters are oversaturated with respect to calcium carbonate, that no equilibrium conditions exist and that phosphorus removal has led to undetectable changes in calcium carbonate oversaturation. Hence, it is concluded that the primary changes in phosphorus levels within the river is directly associated with changing point source contributions from the STW and physical dilution within the river. However (1) the results relate to only the first year of study and subsequent differences may become apparent and (2) reactions between the water column and plant and bottom sediment interfaces may be important in regulating phosphorus fluxes within the river. The results presented in this paper mark a pilot phase of a longer-term initiative and this paper provides a background setting. The paper discusses the longer-term objectives and important gaps in knowledge of the system that requires further address.

England↗

PubMed2000

Riverine inputs of major ions and trace elements to the tidal reaches of the River Tweed, UK.

This paper examines spatial and temporal variability in freshwater inputs of trace elements and major ions to the tidal reaches of the River Tweed. The relationships between concentrations of major ions and trace elements (in dissolved and acid-available particulate forms) and flow are examined, and a simple two-component endmember mixing analysis performed to link river water chemistry to catchment sources, and to identify whether within-river processes modify concentrations to produce non-conservative behaviour. The results indicate that most dissolved major ions and trace elements behave conservatively in the lower reaches of the River Tweed, the variability in concentrations being dominated by hydrology and the existence of different high-flow and low-flow endmember runoff chemistries. This suggests that the variability in concentration of most dissolved trace elements and major ions in the lower Tweed can be modelled using simple mixing relationships. However, the relationships between pH, Ca, Mg and Gran alkalinity show pronounced non-conservative behaviour, indicating the importance of understanding within-river process for modelling these determinants. The non-conservative behaviour identified is related to biological controls and the resultant diurnal variations in pH which promote daytime removal of Ca from solution by precipitation of calcium carbonate (and corresponding removal of Mg by co-precipitation) during extreme low-flow conditions and algal blooms during the summer.

Eutrophication↗

PubMed2000

The water quality of the River Trent: from the lower non-tidal reaches to the freshwater tidal zone

The water quality of a major river system, the River Trent, which flows into the Humber estuary and drains large centres of population and industry in central England, is examined in terms of trace element, nutrient, major-ion, suspended sediment and carbon concentrations and set within the context of the transition from non-tidal to the tidal freshwater reaches. Detailed investigation of the water quality variability in the non-tidal river Trent has revealed mainly simple patterns in dissolved chemical concentrations, controlled largely by hydrology and the mixing of baseflow and stormflow endmember chemistries. However, silicon, carbon and nitrate show much more complex behaviour, as concentrations of these chemical determinands are regulated by in-stream biological processes. Major increases in concentrations of suspended solids and acid-available particulate (AAP) trace elements are shown to be linked to tidal mobilization of sediment and the location of the 'turbidity maximum'. Reductions in the concentrations of AAP trace elements per gram of suspended sediment suggest the mobilization of a different sediment type with a lower trace element content, which may result from: (i) a secondary sediment source; or (ii) mobilization of coarser-grained sediment under the stronger tidal hydrodynamic forces. Increased correlations for AAP-trace element interrelationships downstream suggest increasing simplicity of mixing relationships.

Journal Article↗

PubMed2000

Verbal working memory in HIV-seropositive drug users.

Recent evidence suggests that HIV-seropositive drug users are impaired on tasks of visuospatial working memory compared with drug users seronegative for HIV. In the current study we evaluated the performance of 30 HIV-seropositive male drug users and 30 risk-matched seronegative controls on two measures of verbal working memory, the Listening Span and the verbal Self Ordered Pointing Task. Impaired working memory performance was significantly more common among HIV-seropositive persons compared to controls, with the highest incidence of deficit among symptomatic participants. These findings indicate that working memory deficits in persons with HIV are not domain-specific and can be demonstrated reliably in drug users.

Adult↗

PubMed2000

Thought disorder in schizophrenia and mania: impaired context.

This research studied hypotheses that positive thought disorder in schizophrenia is influenced by patients' not taking in immediate target contextual material, thereby losing vital cues that guide thought processes. We assessed 164 acute inpatients (including 55 schizophrenia and 31 bipolar disorder patients), using standardized measures of thought disorder. We also used new measures that assessed (1) total ignoring of context, and (2) straying from the context. Results were as follows: (1) only 9 percent of the schizophrenia patients showed strong evidence of completely ignoring the external context; (2) straying from the external context while simultaneously maintaining part of the context was significantly more common than complete absence of context (p < 0.01); (3) patients with thought disorder strayed from the context significantly more than patients without thought disorder (p < 0.001); and (4) straying from the context was involved in the thought disorder of some, but not all, schizophrenia and mania patients. The data suggest that thought disorder in schizophrenia is not typically due to a failure to "hear" or to take in the relevant contextual material necessary for an appropriate response. Loss of context is involved in some, but not all, thought disorder in schizophrenia and mania.

Adult↗

PubMed2000

Ten-year outcome: patients with schizoaffective disorders, schizophrenia, affective disorders and mood-incongruent psychotic symptoms.

BACKGROUND: It is unclear whether outcome in schizoaffective disorders is more similar to schizophrenia or affective disorders. AIMS: To provide longitudinal data on clinical course and outcome in schizoaffective disorders versus schizophrenia and affective disorders, and determine whether mood-incongruent psychotic symptoms have negative prognostic implications. METHOD: A total of 210 patients with schizoaffective disorders, schizophrenia, bipolar manic disorders and depression were assessed at hospitalisation and then followed up four times over 10 years. RESULTS: At all four follow-ups, fewer patients with schizoaffective disorders than with schizophrenia showed uniformly poor outcome. Patients with mood-incongruent psychotic symptoms during index hospitalisation showed significantly poorer subsequent outcome (P < 0.05). CONCLUSIONS: Schizoaffective outcome was better than schizophrenic outcome and poorer than outcome for psychotic affective disorders. Mood-incongruent psychotic symptoms have negative prognostic implications. The results could fit a symptom dimension view of schizoaffective course.

Acute Disease↗

PubMed1999

Depression during the longitudinal course of schizophrenia.

This prospective research investigated the occurrence and persistence of depression during the longitudinal course of schizophrenia. The research goals were to (1) compare depression in schizophrenia with that in schizoaffective and major depressive disorders, (2) assess whether some schizophrenia patients are vulnerable to depression, and (3) assess the relationship of depression to posthospital adjustment in schizophrenia. A total of 70 schizophrenia, 31 schizoaffective depressed, 17 psychotic unipolar major depressed, and 69 nonpsychotic unipolar major depressed patients were assessed during hospitalization and prospectively assessed for depression, psychosis, and posthospital functioning at 4.5- and 7.5-year followups. A large number (30% to 40%) of schizophrenia patients evidenced full depressive syndromes at each followup, including a subgroup of patients who evidenced repeated depression. Even when considering the influence of psychosis on outcome, depression in schizophrenia was associated with poor overall outcome, work impairment, lower activity, dissatisfaction, and suicidal tendencies. During the post-acute phase assessed, neither the rates nor the severity of depressive syndromes differentiated depression in schizophrenia from schizodepressive or major depressive disorders. However, the depressed schizophrenia patients showed poorer posthospital adjustment in terms of less employment, more rehospitalizations, and more psychosis than the patients with primary major depression. The high prevalence of depression in schizophrenia warrants its incorporation into theory about the disorder. A continuum of vulnerability to depression contributes to the heterogeneity of schizophrenia, with some schizophrenia patients being prone to depression even years after the acute phase. Depression in schizophrenia is one factor, in addition to psychosis, associated with poor outcome and requires specific attention to the treatment strategies by psychiatrists.

Adult↗

PubMed1999

Thought disorder and psychosocial functioning in schizophrenia: the concurrent and predictive relationships.

Recent findings have linked impairments in social performance among individuals with schizophrenia to deficits in cognition. However, one component of cognition, thought disorder (TD), has received little attention in its association with social functioning. The current investigation examined the cross-sectional and predictive relationships between bizarre-idiosyncratic thought and psychosocial functioning throughout the early course of schizophrenia and compared these relationships to those observed among individuals with affective disorders (i.e., bipolar disorder, manic type, and major depression without psychotic features). Participants were assessed on TD, work, and social functioning using standardized procedures across three follow-ups over an 8-year period. The cross-sectional relationships between TD and impairment in work performance were generally significant. TD also significantly predicted subsequent work functioning years later. Less support was found for the relationship between TD and social functioning. Finally, the relationship between TD and work performance appeared to be more consistent over time for the subjects with schizophrenia compared to those with affective disorders. The results suggest that techniques which minimize TD may have implications for occupational functioning among persons with chronic psychiatric disorders.

Adaptation, Psychological↗

PubMed1999

Psychosis and functioning as risk factors for later suicidal activity among schizophrenia and schizoaffective patients: a disease-based interactive model.

The present research explores the relationship of positive symptoms, negative symptoms, and posthospital functioning to subsequent suicidal behavior over a 7 1/2-year period, and examines whether these patterns vary with diagnosis. The results support a multifactor model of suicide risk. Both psychosis and poor functioning show some relationship to later suicidal activity for both schizophrenic and schizoaffective patients. Psychosis may remain a risk factor for suicidal activity for schizoaffective patients, even when functioning is partialed out. This is in contrast to the schizophrenia patients, for whom funtioning seems to mediate the effects of psychosis on later suicidality. In general, adequacy of overall posthospital functioning mediates the effects of some risk factors on suicidal activity within different diagnostic groups.

Adult↗

PubMed1997

Longitudinal courses of thought disorder in schizophrenia and schizoaffective disorder.

This research examined the longitudinal courses of thought disorder in schizophrenia, schizoaffective disorder, and other psychotic and nonpsychotic disorders. One-hundred-eighty young psychiatric inpatients were prospectively diagnosed at an early stage of illness and followed up and evaluated for thought disorder at 2, 4.5, and 7.5 years post-index hospitalization. Patterns of thought disorder were examined in relation to diagnosis, index thought disorder, demographic characteristics, prognostic factors, clinical states of psychosis, outcome at followup, and treatment. Courses of frequent and persistent thought disorder were most frequently found in schizophrenia. The prevalence and course of thought disorder over time in schizoaffective disorder laid between those in schizophrenia and those in other psychotic disorders. Demographic factors were not predictive of the course of thought disorder. Diagnosis, the presence of thought disorder at index, pre-index work and academic competence, and pre-index social functioning were associated with courses of thought disorder (when courses were classified as remitted/infrequent and frequent/persistent). The longitudinal relationships between thought disorder and psychosis suggested that, in schizophrenia, thought disorder is not simply a function of psychosis. Thought disorder appeared more closely tied to the presence of psychosis over time in schizoaffective disorder. Increased inquiry into the factors associated with different courses of thought disorder across psychiatric disturbances appears merited.

Adult↗

PubMed1997

Course and outcome for schizophrenia versus other psychotic patients: a longitudinal study.

We studied 276 patients longitudinally, beginning at the acute phase and continuing at three successive followups over 7.5 years, comparing 74 schizophrenia patients with 74 other psychotic patients and 128 nonpsychotic patients on early course and outcome. Schizophrenia patients showed significantly poorer functioning than patients with other psychotic disorders at each of the three followups (p < 0.05). More schizophrenia patients than other psychotic patients showed consistent psychopathology and a course in which there was not complete remission at any of the three followups (p < 0.05). Most schizophrenia patients did not show severe decrements in social activity level. Poor outcome schizophrenia patients showed significantly slower recovery at each followup than did other psychotic patients with initial poor outcomes (p < 0.01). The results indicate that, during the early course, schizophrenia patients still show relatively poor outcomes, although a small number of schizophrenia patients enter into complete remission. Over time, many schizophrenia patients fluctuate between severe disability and moderate disability rather than always showing severe disability. Schizophrenia patients tend to recover more slowly then other psychotic patients. Differences between schizophrenia patients and other psychotic patients in clinical course over time may be larger than differences at any single followup.

Adult↗

PubMed1997

Neuropsychological dysfunction and clinical outcome in psychiatric disorders: a two-year follow-up study.

The presence of neuropsychological disturbances in schizophrenia and mood disorders raises the question that cognitive impairments might contribute to poor outcome. This report examines changes in neuropsychological performance from hospitalization to a 2-year follow-up evaluation in relation to psychosocial outcome. Findings indicated that unfavorable clinical outcome is associated with marginal changes in neuropsychological performance, whereas good outcome status is associated with neuropsychological improvement. Neuropsychological improvement may thus require a stable period of favorable psychosocial recovery, in schizophrenia and schizoaffective disorder, as well as major mood disorder syndromes.

Adult↗