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Biomedical subjects

P Dickens

Publications and source records attributed to P Dickens.

At least 19 recordsLinked to original sources
PubMed1992

Acute hemorrhagic myocarditis in systemic lupus erythematosus.

We report a 46-year-old patient with longstanding systemic lupus erythematosus (SLE) who developed rapidly progressive heart failure and died. At postmortem, there was a unique picture of hemorrhage and mild inflammation present in the myocardium causing the heart failure. As far as we are aware, this picture has not been described before in SLE and is similar to that seen in the cardiac allograft hyperacute rejection.

Coronary Vessels↗
PubMed1992

Sudden death associated with solitary intracavitary right atrial metastatic tumour deposit.

We report a case of cardiac metastasis of primary adrenal cortical carcinoma to the endocardium of the right atrium resulting in an intracavitary mass which we believe caused sudden death by blocking the tricuspid valve orifice. We have been unable to find a similar case previously reported although primary atrial myxoma is well known to be a rare cause of sudden cardiac death by the same mechanism. Modern non-invasive imaging techniques have facilitated recognition of intracavitary cardiac metastases, and with surgical intervention, when feasible, the risk of sudden cardiac death can be reduced.

Adrenal Cortex Neoplasms↗
PubMed1992

Tuberculous myocarditis presenting as sudden cardiac death.

A 71-year-old Chinese male presented as sudden death and autopsy revealed miliary tuberculosis with tuberculous myocarditis. Though miliary tuberculosis is not as common as in the past, it remains one of the possible causes of sudden cardiac death.

Aged↗
PubMed1992

Rapid death from thrombotic thrombocytopaenic purpura following caesarean section.

We report a case of rapid death from thrombotic thrombocytopaenic purpura (TTP) in a young pregnant lady who developed full blown symptoms soon after caesarean section. Extensive intramyocardial confluent haemorrhages and widespread microthrombi in heart, brain, adrenals and kidney were found at autopsy. Thrombotic thrombocytopaenic purpura is an uncommon condition, which carries a high fatality rate if untreated. Awareness of this syndrome together with its high risk of sudden death underlines the importance of rapid diagnosis and treatment.

Adrenal Cortex↗
PubMed1992

Sudden death from secondary massive pulmonary embolism derived from marrow emboli trapped by Chiari's network.

We report a case of fatal massive pulmonary embolism in an 86-year-old woman. The embolus occurred as a result of embolic bone marrow particles from a fractured femur becoming trapped by a Chiari's network which then acted as a source for propagation of a large thrombus which detached and caused sudden death from massive pulmonary embolism. To our knowledge this is the first report of such a case.

Aged↗
PubMed1992

Human papillomavirus 16/18 and nasopharyngeal carcinoma.

Sixteen cases of nasopharyngeal carcinoma (eight anaplastic and eight well differentiated squamous types) were examined for the presence of human papillomavirus types 16 and 18 genomes using the polymerase chain reaction on paraffin wax embedded biopsy specimens. Although nasopharyngeal carcinoma, particularly the anaplastic type, is strongly associated with Epstein-Barr virus, other factors may be involved in its pathogenesis. No DNA of either human papillomavirus subtype was detected. It is concluded, therefore, that these two "high risk" types of human papillomavirus are not implicated in the pathogenesis of nasopharyngeal carcinoma. The number of cases in this series was small, however, and further studies are warranted using fresh biopsy material and including other viral subtypes.

Base Sequence↗
PubMed1992

Nasopharyngeal carcinoma in situ in nasopharyngeal carcinoma.

AIMS: To assess the presence of carcinoma in situ (CIS) in patients with nasopharyngeal carcinoma (NPC) and to see if the number of biopsy sites facilitates detection of CIS. METHODS: Formalin fixed, paraffin wax embedded biopsy specimens (n = 285) from 187 patients with NPC in 1987 were studied for the presence of CIS as well as for the histological assessment of the subtype of CIS. RESULTS: Fifteen (8.0%) patients had CIS, representing 8.3% of all new patients with NPC and 11.6% of patients with persistent disease or relapse. CIS was undifferentiated or poorly differentiated, no cases of well differentiated squamous cell CIS were identified. There was no significant difference in the incidence of CIS when multiple endoscopic biopsy specimens were taken rather than single forceps biopsy specimens. CONCLUSIONS: CIS can only be identified in a few patients with NPC largely because of late presentation with advanced disease at the time of diagnosis and the focal nature of the dysplastic process. The presence of dysplasia in relapses of NPC suggests that these tumours may be second growths rather than regrowths of a primary tumour.

Carcinoma in Situ↗
PubMed1992

Epstein-Barr virus DNA in nasopharyngeal carcinomas from Chinese patients in Hong Kong.

AIMS: To investigate the presence of Epstein-Barr virus (EBV) in cases of nasopharyngeal carcinoma (NPC) in Chinese patients living in Hong Kong. METHODS: Nasopharyngeal biopsy specimens, formalin fixed and paraffin wax embedded, from 24 patients, eight with undifferentiated nasopharyngeal carcinoma, eight with well differentiated squamous carcinoma, and eight showing normal tissue histology, were analysed for the presence of Epstein-Barr virus (EBV) DNA by slot-blot hybridisation on extracted unamplified DNA, and also after amplification of EBV specific sequences by the polymerase chain reaction (PCR). RESULTS: DNA slot-blot analysis showed viral DNA in all the undifferentiated, five of the well differentiated tumours, and none of the normal biopsy specimens. PCR studies confirmed positivity in the eight undifferentiated tumours, but six of the well differentiated tumours and three of the normal biopsy specimens showed viral DNA by this method, illustrating its greater sensitivity. CONCLUSIONS: EBV genome is present in appreciable copy number in most cases of well differentiated NPC in Chinese patients in Hong Kong.

Base Sequence↗
PubMed1991

Human papillomavirus 6, 11, and 16 in laryngeal papillomas.

Twenty-seven cases of benign laryngeal papillomas, both single and multiple variants, were analysed for human papillomavirus (HPV) by DNA slot-blot hybridization chiefly to determine the pattern of infection in Hong Kong Chinese. DNA was extracted from paraffin blocks of formalin-fixed tissue and probed separately for HPV 6, 11, 16, and 18. Sixteen cases (59 per cent) showed the presence of at least one of these four HPV genomes. Thirteen cases (48 per cent) were positive for HPV 11 only. Three other cases (11 per cent) showed triple positivity for HPV 6, 11, and 16. None were positive for HPV 18. The predominance of HPV 11 infection contrasts with other series which have shown either an almost equal distribution of HPV 6 and 11 or a predominance of HPV 6. The finding of HPV 16 in three cases was unexpected. Using the polymerase chain reaction (PCR) with primers complementary to the upstream regulatory region of the HPV 16 viral DNA, the presence of HPV 16 genome was confirmed in all three cases. As the number of HPV 16-positive cases in this study is small, analysis of more cases using fresh biopsy material and a wider range of HPV type-specific PCR primers is warranted to determine the relative incidence of HPV subtypes in these benign laryngeal papillomas.

Adolescent↗
PubMed1991

Fulminant tuberculous bronchopneumonia in a young Hong Kong Chinese woman.

A 24-yr-old, previously healthy Chinese woman presented with symptoms of acute bronchopneumonia which led to acute respiratory failure and death 6 days after admission to hospital despite intensive antibiotic treatment. Autopsy showed acute tuberculous bronchopneumonia of the acinar type. This is a rare presentation and outcome of tuberculous infection in Hong Kong, where 124 cases per 100,000 population were notified in 1988, and indicates that tuberculosis can mimic acute bronchopneumonia and should be considered in cases so presenting, particularly when there is no growth on routine culture and no response to conventional antibiotics. Acute respiratory failure developing in such cases can cause a delay in the diagnosis of tuberculosis.

Adult↗
PubMed1991

Nonbacterial thrombotic endocarditis in Hong Kong Chinese.

Fifty-two Hong Kong Chinese cases of nonbacterial thrombotic endocarditis at autopsy were reviewed to ascertain if there was any difference in autopsy incidence, associated diseases, age and sex incidence, distribution of infarcts, and pattern of valve involvement compared with that in previously reported series. The overall autopsy incidence was 0.68%, within the range of previous reports. Forty-one cases (79%) were associated with malignant neoplasms; the remaining 11 cases were associated with miscellaneous disorders. Adenocarcinoma was associated with 27 (52%) of the cases. Unusual findings were the association of five cases with intrahepatic cholangiocarcinoma and four cases with esophageal squamous carcinoma. This is explicable on the basis of a higher incidence of these two tumors in Hong Kong Chinese than in Western populations, ie, the source of most other reported series. Sex and age incidence, the distribution of infarcts, and the pattern of valve involvement were similar to those reported in other series of nonbacterial thrombotic endocarditis.

Adolescent↗
PubMed1990

Osteosarcoma of the maxilla in Hong Kong Chinese postirradiation for nasopharyngeal carcinoma. A report of four cases.

Postirradiation osteosarcoma of the maxilla was seen in four Hong Kong Chinese patients treated for nasopharyngeal carcinoma. These cases represent four of 42 (9%) cases of osteosarcoma at all sites in this institution during the period 1979 to 1989, when more than 1000 patients were treated with radiotherapy for nasopharyngeal carcinoma. The latent periods varied from 8 to 11 years from completion of radiotherapy treatment to development of osteosarcoma. The radiation dosage varied from 6000 to 6280 cGy in three of the patients. These cases fit the criteria for diagnosis of postirradiation sarcomas. Maxillary osteosarcomas after irradiation for nasopharyngeal carcinoma do not appear to have been described. The very high incidence of nasopharyngeal carcinoma (for which radiotherapy is the treatment of choice) in Hong Kong Chinese would make the occurrence of such tumors more likely in Hong Kong, although the small risk does not contraindicate the use of radiation in the treatment of nasopharyngeal carcinoma in view of its well-documented efficacy.

Adult↗
PubMed1988

The development of Alzheimer's disease in Down's syndrome assessed by auditory event-related potentials.

Several studies have reported changes in auditory event-related potentials in patients with Alzheimer's type dementia. These include an increase in latency and a reduction in amplitude of the P300 (P3) response, a late positive component generated about 300 ms after an unexpected stimulus. Alzheimer's type dementia is an almost invariable acompaniment of ageing in Down's syndrome. This study was designed to assess the usefulness of the auditory P300 response as a measure of the onset of dementia in Down's subjects, who because of poor language development may be difficult to assess by psychological tests. Auditory event-related potentials were recorded from 89 Down's subjects, aged 16-66 years. A control group of 29 mentally retarded subjects with fragile-X syndrome and 83 normal volunteer controls were also tested. Clinical psychological testing found evidence of dementia in 16 Down's subjects and none with fragile-X. Furthermore, in the Down's population but not the fragile-X or control groups, there was a marked increase in P300 latency with age starting around 37 years. In controls, the effect of age on P300 latency became significant some 17 years later around the age of 54 years. The premature effect of age on P300 in Down's syndrome was due to the prolonged P300 latency in the 16 subjects showing signs of dementia. It was confirmed that P300 latency increase reflects the development of Alzheimer's dementia in Down's subjects.

Adolescent↗
PubMed1988

Auditory P300 response in the assessment of Alzheimer's disease in Down's syndrome: a 2-year follow-up study.

Sixty-five subjects with Down's syndrome were followed up and retested 2 years after the initial recording of auditory P300 (P3) event-related potential described in a companion paper (Blackwood et al., 1988). The number of subjects showing clinical evidence for Alzheimer's type dementia had increased by a further 14%. In subjects showing clinical deterioration over a period of 2 years, 78% (7/9) had an increase in P3 latency which was three standard deviations or greater than the group mean. None of the 20 fragile-X group retested showed significant change after 2 years. The results suggest that P3 change may be a sensitive index of the onset of Alzheimer's type dementia in Down's syndrome.

Adolescent↗
PubMed1988

Anger control.

Anger is a poorly understood but very common emotion. When it is misdirected or uncontrolled it becomes dangerous. An analysis of anger and a treatment paradigm is presented, and we outline a research project in which we are using the approach with a group of mentally handicapped adults.

Aggression↗
PubMed1987

P3 abnormality in fragile X syndrome.

P300 (P3) and other long latency auditory event-related potentials (ERPs) were recorded in 33 adults with fragile X syndrome. All patients had an abnormal P3. It was longer in latency and smaller in amplitude than in controls. In several cases, it was split into two separate components, and in others, was generated in response to expected as well as unexpected events. Abnormal P3 was not related to age, percentage cell fragility, or intellectual ability, but complete splitting was associated with the presence of physical dysmorphisms. Our results are interpreted as showing that in fragile X syndrome there is dysgenesis of the hippocampus and related brain structures.

Adolescent↗
PubMed1985

Visual discrimination learning in mentally handicapped adults: comparative effects of two-choice and multiple-choice training methods on stimulus generalization performance.

The hypothesis that in mentally handicapped subjects a multi-choice discrimination learning method would result in superior generalization performance to the traditional two-choice method was investigated experimentally. Twenty-four mentally handicapped adults matched for age, intelligence and duration of institutionalization were divided into two equal groups and given visual discrimination training using a differential reinforcement, prompt-fading procedure. The groups were allocated separately to a two-choice and four-choice training condition in which the discriminative stimulus was associated with one and three non-discriminative stimuli respectively. Following training, stimulus discrimination performance was compared on a generalization test comprising increasing levels of distraction. The results showed a clear advantage for multi-choice training over two-choice. However, it was found that during generalization testing discriminative performance deteriorated as a function of increasing distraction in both groups, suggesting an underlying selective attention defect. Such a defect may be characteristic of stimulus generalization performance in the mentally retarded. Multi-choice discrimination learning appeared partly to counteract major generalization failure when the ratio of non-discriminative to discriminative stimuli was high.

Adult↗