Proton Spectroscopy in a Cross-Section of HIV-Positive Asymptomatic Patients Receiving Immediate Compared with Deferred Zidovudine (Concorde Study)

The purpose of this study was to examine by proton spectroscopy for any difference in cerebral metabolites in patients taking part in the Concorde study (comparing the efficacy of immediate versus deferred treatment with zidovudine on asymptomatic HIV infected individuals). Forty seven HIV positive male patients [29 immediate, 18 deferred zidovudine] were examined in the last 9 months of the therapeutic trial. Magnetic resonance imaging and proton spectroscopy were performed at 1.5 Tesla using a single voxel placed in the parieto-occipital white matter. No significant difference was found in metabolite ratios comparing immediate versus deferred zidovudine (NA/NA+Cho+Cr 0.52 vs. 0.52). High quality spectra were acquired in relatively large numbers of patients and logistically spectroscopy may be applied to clinical therapeutic studies.

Understanding jumping to conclusions in patients with persecutory delusions: working memory and intolerance of uncertainty

BACKGROUND

Persecutory delusions are a key psychotic experience. A reasoning style known as 'jumping to conclusions' (JTC) - limited information gathering before reaching certainty in decision making - has been identified as a contributory factor in the occurrence of delusions. The cognitive processes that underpin JTC need to be determined in order to develop effective interventions for delusions. In the current study two alternative perspectives were tested: that JTC partially results from impairment in information-processing capabilities and that JTC is a motivated strategy to avoid uncertainty.

METHOD

A group of 123 patients with persistent persecutory delusions completed assessments of JTC (the 60:40 beads task), IQ, working memory, intolerance of uncertainty, and psychiatric symptoms. Patients showing JTC were compared with patients not showing JTC.

RESULTS

A total of 30 (24%) patients with delusions showed JTC. There were no differences between patients who did and did not jump to conclusions in overall psychopathology. Patients who jumped to conclusions had poorer working memory performance, lower IQ, lower intolerance of uncertainty and lower levels of worry. Working memory and worry independently predicted the presence of JTC.

CONCLUSIONS

Hasty decision making in patients with delusions may partly arise from difficulties in keeping information in mind. Interventions for JTC are likely to benefit from addressing working memory performance, while in vivo techniques for patients with delusions will benefit from limiting the demands on working memory. The study provides little evidence for a contribution to JTC from top-down motivational beliefs about uncertainty.

What makes one person paranoid and another person anxious? The differential prediction of social anxiety and persecutory ideation in an experimental situation

BACKGROUND

In recent years a close association between anxiety and persecutory ideation has been established, contrary to the traditional division of neurosis and psychosis. Nonetheless, the two experiences are distinct. The aim of this study was to identify factors that distinguish the occurrence of social anxiety and paranoid thoughts in an experimental situation.

METHOD

Two hundred non-clinical individuals broadly representative of the UK general population were assessed on a range of psychological factors, experienced a neutral virtual reality social environment, and then completed state measures of paranoia and social anxiety. Clustered bivariate logistic regressions were carried out, testing interactions between potential predictors and the type of reaction in virtual reality.

RESULTS

The strongest finding was that the presence of perceptual anomalies increased the risk of paranoid reactions but decreased the risk of social anxiety. Anxiety, depression, worry and interpersonal sensitivity all had similar associations with paranoia and social anxiety.

CONCLUSIONS

The study shows that social anxiety and persecutory ideation share many of the same predictive factors. Non-clinical paranoia may be a type of anxious fear. However, perceptual anomalies are a distinct predictor of paranoia. In the context of an individual feeling anxious, the occurrence of odd internal feelings in social situations may lead to delusional ideas through a sense of 'things not seeming right'. The study illustrates the approach of focusing on experiences such as paranoid thinking rather than diagnoses such as schizophrenia.

Neural correlates of temporal-order judgments versus those of spatial-location: Deactivation of hippocampus may facilitate spatial performance

The retrieval of temporal-order versus spatial-location information was investigated using fMRI. The primary finding in the hippocampus proper, seen in region of interest analyses, was an increase in BOLD signal intensity for temporal retrieval, and a decrease in signal intensity for spatial retrieval, relative to baseline. The negative BOLD signal change with spatial memory processing, while unexpected, is consistent with the recent fMRI literature indicating decreased BOLD can be associated with neuronal activation, and it is argued that the deactivation observed here may facilitate spatial performance. Spatial-location judgments also yielded a stronger (positive) response in the right midfrontal gyrus, while temporal-order judgments (autobiographic condition only) showed greater activity in the left superior temporal gyrus, suggesting greater working memory demands and greater semantization for each judgment type, respectively. Finally, all conditions activated the left midfrontal gyrus, although autobiographic memories showed additional activity in the medial frontal gyrus.

Investigating a simple model of cutaneous wound healing angiogenesis

A simple model of wound healing angiogenesis is presented, and investigated using numerical and asymptotic techniques. The model captures many key qualitative features of the wound healing angiogenic response, such as the propagation of a structural unit into the wound centre. A detailed perturbative study is pursued, and is shown to capture all features of the model. This enables one to show that the level of the angiogenic response predicted by the model is governed to a good approximation by a small number of parameter groupings. Further investigation leads to predictions concerning how one should select between potential optimal means of stimulating cell proliferation in order to increase the level of the angiogenic response.

Investigation of the human hippocampal formation using a randomized event-related paradigm and Z-shimmed functional MRI

Functional neuroimaging of the hippocampal formation has presented a challenge to neuroscientists because of the small size of the hippocampus proper and its location at the basal level of the brain. Choosing the appropriate control condition for subtraction-based studies has also proved difficult. Event-related experimental designs are a powerful tool in behavioral and electrophysiological studies. Recently, such experimental designs have been applied to functional MR imaging studies but these studies used large intertrial intervals in order to separate the slow blood flow response from temporally adjacent events, severely limiting the number of events that can be presented in a single run. This leads to poor statistical power and restrictions on the design of the experimental paradigm. We present data obtained using a rapidly presented, randomized event-related paradigm, combined with a novel fMRI imaging method designed to improve imaging in basal brain regions. The results demonstrate bilateral activation in the hippocampal formation in identification of novel complex scenes distinct from a learned basis set of complex scenes. Differential activation is obtained in the counter task of identifying a learned target complex scene against a background of novel scenes. The results are also compared with the more conventional block design complex scene paradigms previously reported by others. The block design provides strong posterior activation, likely related more to visual scene processing, whereas the event-related design provides more anterior hippocampal activation with the encoding of novel scenes.

Supracondylar humerus fractures in children. Comparison of operative treatment methods

A retrospective analysis was performed of 87 children treated operatively for supracondylar humerus fractures by 18 different surgeons during a 6-year period. No patient suffered from compartment syndrome or Volkmann's ischemic contracture. Early postoperative fracture displacement occurred in four (7%) of 60 patients with Type III fractures, and in one (4%) of 23 patients with Type II fractures. Displacement occurred in one (2%) of 52 Type III fractures stabilized with crossed medial and lateral Kirschner wires, whereas displacement occurred in two (28%) of seven Type III fractures stabilized with lateral wires only. Thirty-four patients could be located for long-term followup; complete examination of both upper extremities was performed on these 34 patients at an average of 33 months postoperatively. The long-term results were excellent in 19 (56%), good in seven (21%), fair in one (3%), and poor in seven (21%) patients. Five additional patients were not available for followup at the time of the current study, but had followup of at least 6 months available. Of the 39 patients with followup of at least 6 months, five patients' fractures (13%) healed with coronal plane malalignment greater than 10 degrees which resulted in gunstock deformity. There was no statistically significant relationship between treatment method and gunstock deformity. However, none of the patients with gunstock deformity had compromised activity because of the deformity, and all had full elbow extension and at least 130 degrees elbow flexion.

Neurophysiological changes associated with psychiatric symptoms in HIV-infected individuals without AIDS

HIV-1 infection may be complicated by a number of psychopathological conditions. While organic mental disorders, such as HIV-related psychosis and dementia, are late manifestations, mood disorders may occur during both asymptomatic and symptomatic stages of infection. The possible impact of brain involvement due to neurotropism of HIV-1 has not been investigated systematically in these latter conditions. The psychiatric caseness of HIV-seropositive individuals without AIDS and seronegative controls was assessed using a standardized clinical interview (Present State Examination). A comparison was made between individuals with and without psychiatric caseness using clinical, neuropsychological, and neurophysiological assessments. An increased prevalence of current psychiatric illness was found in subjects with early symptomatic HIV infection compared to those with asymptomatic infection and controls. This could not be attributed to psychiatric history, as well as to clinical and immunological markers of HIV infection, however, psychiatric caseness in early symptomatic infection was associated with marked neurophysiological changes, detectable by quantitative electroencephalography. Altogether, this study provided preliminary evidence that psychiatric symptoms in symptomatic but not asymptomatic HIV infection may be associated with subtle brain involvement preceding the immunological and neurocognitive impairment characteristic for AIDS.

Suicidal behaviour and HIV infection--is there a link?

The association between suicidal behaviour and HIV infection has been the subject of much attention in recent years. In this paper we review the evidence about the prevalence of suicide, suicidal ideation and deliberate self-harm in individuals with HIV infection. Finally we discuss the significance of the findings, in particular some of the methodological problems encountered in this field.

Classical and novel approaches to the detection and localization of the numerous modified nucleotides in eukaryotic ribosomal RNA

Human ribosomes contain more than 200 modified nucleotides. These are made up as follows: more than 100 2'-O-methyl groups, 10 methylated bases, about 95 pseudouridines and at least one other modification. Other mammalian sources that have been examined, as well as the lower vertebrate Xenopus laevis, show very similar patterns of nucleotide modifications, especially as revealed by oligonucleotide fingerprinting for methyl groups. Most of the methyl groups have been located along the rRNA primary structure by matching oligonucleotide sequence data to the complete sequences derived from rDNA. Nearly all of the methyls are in conserved core regions. Saccharomyces carlsbergensis ribosomes contain about 55% as many methyls as vertebrate ribosomes. The locations of most of the S carlsbergensis methyls are also known. However, of the numerous other eukaryotes whose rRNA sequences have been determined indirectly from rDNA, few have yielded detailed data on modified nucleotides. This is in part because the methods applied to vertebrate and yeast ribosomes are highly laborious and are not universally applicable. Therefore in the final part of this paper we briefly review other methods that have been applied to the detection and localization of modified nucleotides in rRNA. In particular, we outline progress towards developing a method whereby reverse transcription shows characteristic pausing at most of the 2'-O-methylation sites in human and Xenopus 18S rRNA. 2'-O-Methylation pauses are distinguishable from most other interruptions; the 2'-O-methyl pauses occur more strongly at low than at high dNTP concentration, whereas most other interruptions are independent of dNTP concentration.

Long-term nutrient enrichment of an estuarine system: Ythan, Scotland (1958-1993)

A comprehensive review is given of past and current annually averaged nutrient concentrations (total oxidised nitrogen [TON], phosphate and silicate) in the River Ythan and its estuary. TON concentrations in the River Ythan have increased from ca 100-150 microm in the late 1960s to ca 500-550 microm in the early 1990s, changes which are also shown in the estuary. The interpretation of the phosphate data is more complex but concentrations in the estuary also appear to have increased. Silicate concentrations have remained constant with time. The results of 11 surveys of the estuary completed during 1993 are given. TON and silicate behave conservatively in the estuary, with concentrations determined by those of the fresh water end-member and hence by processes within the catchment. Phosphate and ammonia concentrations at low salinity are affected by the discharge from the Ellon sewage treatment facility at the head of the estuary. Throughout the estuary there is evidence of an input of ammonia to the water column from the sediments, but it represents only ca 0.2-2% of the nitrogen entering from the River Ythan. Despite the increased nutrient loading to the estuary there is no evidence that this has resulted in higher chlorophyll concentrations in the water column, this observation is attributed to the relatively short flushing period of the estuary.

A longitudinal study of the neuropsychiatric consequences of HIV-1 infection in gay men. II. Psychological and health status at baseline and at 12-month follow-up

The aim of this study was to determine whether HIV infection is associated with increased psychosocial distress in the asymptomatic and early symptomatic stages of disease and to determine the factors associated with reporting health symptoms. Subjects included 61 gay men (41 HIV--, 20 HIV+) who were assessed at the time of requesting their first HIV test and again 12 months later. Measures included a detailed standardized psychiatric interview (Present State Examination, PSE), a range of psychosocial self-report measures and a physical symptom checklist. There were no differences between the HIV+ and HIV-- groups in terms of self-reported symptoms. Multiple regression analysis showed that the symptom reporting was not associated with clinical or immunological markers of disease progression but was associated with measures of psychosocial distress. Although both groups showed elevated levels of psychosocial distress at the time of HIV testing, there were no differences between serostatus groups at follow-up. Multiple regression analysis indicated that the best predictors of PSE scores at follow-up were baseline PSE score and a history of psychiatric illness. Early HIV disease is not associated with increased psychosocial distress and symptom reporting is more closely related to psychological measures than to clinical or immunological markers of disease.

A longitudinal study of the neuropsychiatric consequences of HIV-1 infection in gay men. I. Neuropsychological performance and neurological status at baseline and at 12-month follow-up

The aim of this study was to determine whether HIV infection is associated with neurological or neuropsychological impairment in the asymptomatic and early symptomatic stages of disease. Subjects included 61 gay men (41 HIV-, 20 HIV+) who were assessed at the time of requesting their first HIV test and again 12 months later. The assessments at baseline were conducted double-blind to HIV serostatus. Measures included a neuropsychological battery, neurological examination and full psychiatric assessment. There were no differences between the asymptomatic HIV+ and HIV- groups at baseline or at follow-up in terms of mean scores on neuropsychological tests. Mean scores were within the normal range for all neuropsychological tests for both groups. Multiple regression analysis was used to predict each individual's performance at follow-up on the basis of their baseline performance, psychiatric state, neurological history and drug use for each of the neuropsychological tests. HIV+ subjects were more likely than control subjects to perform at a significantly lower level at follow-up on one or more tests than predicted on the basis of their baseline performance.

Studies on chymotrypsin-like catalysis by synthetic peptides

The synthetic peptide Chymohelizyme-1 (CHZ-1) exhibits esterase activity against carbobenzoxytyrosine p-nitrophenyl ester (ZTONP), carbobenzoxyalanine p-nitrophenyl ester (ZAONP), and t-butyloxy-carbonyltyrosine p-nitrophenyl ester (BocTONP). However, earlier reports of catalytic activity against less labile esters and amides have proven to be incorrect. The major reason for the errors appears to have been the omission of certain controls in the previous work. Although the catalytic triad does not appear to be functioning as designed, the catalytic activity of CHZ-1 does depend on the integrity of its primary structure. The pH dependence of hydrolysis of ZTONP points to general-base catalysis, whereas a preference for hydrophobic substrates suggest that the structure of CHZ-1 is performing some other role in assisting catalysis.

Gender identity disorder and HIV disease

Four cases of male-to-female transsexuals with HIV infection are described, showing that individuals with gender identity disorder are vulnerable to HIV infection through unsafe sexual behaviour and intravenous drug use. The various practical problems associated with carrying out major surgery on this group of individuals are discussed, as well as some of the ethical issues raised by their treatment needs.

Neuropsychiatric aspects of HIV-1 infection in gay men: controlled investigation of psychiatric, neuropsychological and neurological status

The aim of this study was to determine whether HIV infection is associated with psychiatric morbidity or neuropsychological impairment in asymptomatic and early symptomatic stages of disease in gay men. The subjects were 100 gay men (68 HIV-ve, 32 HIV+ve, 6 being CDC IV). All subjects were recruited at the time of requesting their first HIV test and the assessment was double-blind to HIV serostatus. There were no differences in psychiatric status or neuropsychological performance between the HIV-ve and HIV+ve groups. Multiple regression analysis and logistic regression were used to identify factors associated with psychiatric morbidity, neuropsychological impairment and subjective reporting of memory problems and physical symptoms for all 100 subjects. Previous psychiatric history and current illegal (non-dependent) drug use were associated with psychiatric morbidity, poor education was associated with neuropsychological impairment and psychiatric status (score on HAD and PSE) was associated with subjective reporting of memory problems and physical symptoms.

Detection of subclinical motor dysfunctions in early symptomatic HIV infection with topographical EEG

Motor dysfunctions are amongst the earliest and most common signs of brain impairment caused by human immunodeficiency virus (HIV) infection. Topographical EEG was recorded in patients both with asymptomatic and early symptomatic infection (without acquired immunodeficiency syndrome (AIDS) defining illness), as well as in seronegative controls under resting and motor activation conditions. While patients' motor performance did not differ from control values, the EEG showed a consistent increase in rhythmic activity in Theta, Alpha and Beta frequency bands in Symptomatics. This amplitude increase was evident in different topographical regions during resting states as compared with motor activation, findings which suggest concurrent involvement of several motor areas possibly due to a functional impairment in subcortical integratory mechanisms. Comparing motor task and baseline both patient groups showed less consistent patterns of task-related EEG amplitude reduction than found in the control group. Here topographical EEG in connection with motor activation procedures was found to be more sensitive than behavioral measures of motor performance and offers a technique to assess treatment effects before the development of motor abnormalities in patients with HIV infection.

Suicide and HIV disease

It has been suggested that HIV infection is associated with an increased risk of suicidal behaviour. This paper reviews the literature on suicide in patients with HIV disease and discusses methodological problems encountered in studying the incidence of suicide in this population. A snowballing method was used to identify cases of suicide in patients who were receiving treatment for HIV disease in a central London health district. The possible under detection of suicides among AIDS patients is considered. The six case reports are described to illustrate the clinical and psychosocial characteristics of suicides, and they are discussed in relation to other findings on suicide in patients with HIV disease and other physical illnesses.

Auditory and visual event-related potentials in a controlled investigation of HIV infection

Auditory and visual event-related brain potentials (ERPs) were used to complement neuropsychological and medical assessment in neurologically healthy subjects with asymptomatic and symptomatic human immunodeficiency virus type 1 (HIV-1) infection. Auditory and visual ERPs, recorded using standard oddball paradigms, disclosed delays in late waves (N2 and P3) in symptomatic subjects (CDC stage IV) when compared with matched controls. Abnormally delayed P3 waves in at least one modality were recorded in 41% of symptomatics and this was associated with deficits in neuropsychological performance, particularly psychomotor slowing. However, no differences in late wave latencies between asymptomatic and control subjects were found, though asymptomatics showed delays in auditory N1 and P2 latencies. The number of morphological abnormalities, such as indiscernible late waves as well as topographical variability of the P3 wave, was increased in both HIV seropositive groups and possibly indicates a distinct mechanism of impairment, different from latency delay. Whilst P3 delay in symptomatics was not associated with changes in immune function (T4 cells) there was, however, a link with anaemia and subclinical hepatic dysfunction.