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Biomedical subjects

P Hamilton

Publications and source records attributed to P Hamilton.

At least 19 recordsLinked to original sources
PubMed1995

Basal cell adenocarcinoma of the submandibular gland.

Basal cell adenoma is a well recognized histopathologic variant of monomorphic adenoma of salivary gland, but in recent years there have been occasional reports of malignant basal cell tumors of major salivary glands. We present a case report of one such basal cell adenocarcinoma arising in the submandibular gland and discuss the differential diagnosis and distinction from a basal cell adenoma. We also review the published literature on basal cell adenocarcinoma. This is the first case of basal cell adenocarcinoma to be studied in detail by both immunohistochemistry and electron microscopy. There has been debate in the past as to the cell of origin of salivary gland basal cell tumors and specifically as to whether myoepithelial differentiation occurs in these tumors. The immunohistochemical and ultrastructural features of this case provide evidence for a dual population of ductal and myoepithelial cells. A flow cytometric analysis of nuclear deoxyribonucleic acid content showed the presence of DNA aneuploidy within one tissue block.

Adenocarcinoma↗
PubMed1995

A prospective study of emergent abdominal sonography after blunt trauma.

In North America, the role of emergent abdominal sonography [ultrasonography (US)] after blunt trauma requires further definition. The purpose of this prospective study was to compare US to the gold standards, diagnostic peritoneal lavage (DPL), and computed tomography (CT), in a population of adults after blunt trauma. In 206 adults who required either CT or DPL to assess possible abdominal injury, US was performed, before DPL or CT, and was aimed at the detection of intraperitoneal fluid. The mean Injury Severity Score and Glasgow Coma Scale score were 24.0 and 11.9, respectively. One hundred thirty-seven patients (67%) had CT and 69 (33%) had DPL. The positive and negative predictive values of US for intraperitoneal fluid were 90% and 97%, respectively. The sensitivity, specificity, and accuracy of US for free fluid were 81%, 98%, and 96%, respectively. Of the six false-negative USs, only one required surgery. The US examinations required 2.6 +/- 1.4 min. Emergent abdominal sonography is an accurate, rapid test for the presence of intraperitoneal fluid in adult blunt trauma victims and in these patients may prove valuable as a screening test for abdominal injury.

Abdominal Injuries↗
PubMed1995

Significance of intra-abdominal extraluminal air detected by CT scan in blunt abdominal trauma.

The purpose of this study was to determine the frequency and significance of computed tomographic (CT) scan-detected pneumoperitoneum in blunt abdominal trauma. We retrospectively reviewed 118 consecutive CT scans of the abdomen in blunt abdominal trauma patients (mean Injury Severity Score 24), performed at our Regional Trauma Unit over a 12-month period. Seven (5.9%) patients had intra-abdominal extraluminal air. None of these seven patients had evidence of bowel perforation at laparotomy (two) or on clinical follow-up (five). All seven had chest tubes in place before the CT scan. None of the seven patients were on mechanical ventilation at the time of CT scan. In the setting of blunt abdominal trauma pneumoperitoneum does not necessarily indicate hollow viscus injury. It frequently is secondary to other etiologies, especially dissection of interstitial air from the chest, as suggested in this study. The decision for laparotomy should be based on a combination of the clinical findings, CT scan results, or other diagnostic tests such as peritoneal lavage.

Abdominal Injuries↗
PubMed1994

Hydrochloric acid denaturation of colorectal tumour tissue infiltrated with bromodeoxyuridine.

The thymidine analogue, bromodeoxyuridine, is substituted into DNA during DNA synthesis and can be used to identify those cells which have passed through the S-phase of the cell cycle. Incorporated bromodeoxyuridine can be detected using anti-bromodeoxyuridine monoclonal antibodies which bind to the exposed bromodeoxyuridine in single-stranded DNA after a suitable denaturation step. Hydrochloric acid is the most commonly employed denaturation agent in bromodeoxyuridine monoclonal antibody methodologies. This preliminary study was to validate the hydrochloric acid denaturation step for colorectal tumour tissue infiltrated in vivo with bromodeoxyuridine. Standard immunohistochemistry and flow cytometric techniques using Bu20a were employed across a range of hydrochloric acid concentrations. Although high labelling indices were achieved using acid concentrations of 0.10 M HCl, the optimal hydrochloric acid concentration was not the same in all tumours. Sensitivity of DNA to hydrochloric acid denaturation should be carefully considered in bromodeoxyuridine methodologies using the monoclonal antibody Bu20a.

Antibodies, Monoclonal↗
PubMed1994

Nycthemeral profile of nonspectral heart rate variability measures in women and men. Description of a normal sample and two sudden cardiac arrest subsamples.

Heart rate variability (HRV), a noninvasive systemic index of the central autonomic nervous system, demonstrates considerable within-subject variability, including a strong systematic 24-hour nycthemeral (or less precisely, circadian) component. Recent interest in the timing of sudden cardiac arrest (SCA), especially the pronounced morning rise in sudden deaths, has motivated research into coincident dynamic phenomena in HRV indices of central autonomic nervous system activity. In this study, statistical (nonspectral) HRV measures (SD and %RR50) were summarized for consecutive 15-minute blocks from 24-hour Holter electrocardiogram tapes. Six subgroups were scrutinized: women and men respectively in three clinical strata (normal subjects [n = 85 women and 40 men], SCA with no current or prior myocardial infarction [MI] [n = 9 women and 31 men], SCA with old MI [n = 7 women and 48 men]). Significant nycthemeral effects were observable for all HRV measures in five of the six groups, with a dramatic fall in HRV during the hours of the morning with the highest phenomenologic incidence of SCA. Both strata of SCA subjects had much lower HRV than the normal subjects. This effect was strongest during the night-time hours, particularly for a purported index of vagal tone (%RR50). For reasons that are not known, the nine female SCA survivors who had no current or previous MI presented very distinct 24-hour patterns for the HRV measures studied. Twenty-four-hour profiles of short-term statistical HRV provide a rich field for the observation of within-subject adaptations of the central autonomic nervous system inputs to the heart in both normal and clinical subgroups.

Circadian Rhythm↗
PubMed1994

Contact diode laser cyclo-photocoagulation for refractory glaucoma. A pilot study.

Initial experience with non-contact diode cyclo-photocoagulation for refractory glaucoma has shown positive results. Diode laser irradiation applied via a contact probe results in greater transmission through the sclera and delivery of more energy to the ciliary body. A trial was performed to evaluate the effects of contact diode cyclo-photocoagulation. A total of 12 patients with glaucoma due to conditions such as central retinal vein occlusion were treated. A mean of 22 pulses (810 nm) with powers of up to 2 W and of 2 s duration were applied via a fibre-optic delivery system and a contact probe. The mean intra-ocular pressure dropped from 42.3 to 13.6 mmHg over 3 months. Four patients required retreatment. Three patients had side effects that included hyphaema, anterior fibrinous uveitis and pupil block. In conclusion, contact diode cyclo-photocoagulation had a significant ocular hypotensive action in the treatment of refractory glaucoma. As compared with non-contact diode cyclo-photocoagulation, the contact modality produced more marked non-therapeutic side effects.

Adult↗
PubMed1992

Seroprevalence of antibodies to the human immunodeficiency virus in dialysis workers: results of a multi-center study.

The Center for Devices and Radiological Health, in collaboration with the Department of Veterans Affairs Medical Center, Brooklyn, N.Y., conducted a multi-center, multi-institutional study of the seroprevalence of antibodies to the human immunodeficiency virus (HIV) among dialysis workers. Seven dialysis units and 112 dialysis workers participated in the study over a period of 2 years. Participation was limited to dialysis workers who, by questionnaire, denied non-occupational risk factors for HIV infection. The vast majority of the study participants were drawn from areas where the prevalence of HIV infection and AIDS cases are substantially greater than the national average. Study participants received the ELISA test for HIV antibodies. All 112 of the participants tested negative for HIV antibodies. These results are encouraging, as they failed to reveal unrecognized occupational transmission of HIV infection among dialysis workers.

HIV↗
PubMed1992

Role of intraoperative ultrasonography in hepatic surgery: a preliminary report.

Twenty-four patients who underwent ultrasonography during hepatic surgery in the 22 months from October 1989 to July 1991 were studied prospectively to determine the value, if any, of intraoperative ultrasonography. For 6 (25%) of the 24 patients the operative plan was altered because of the ultrasonographic findings. In one of them resection was extended from a left lateral segmentectomy or sectorectomy to a left hemihepatectomy. In the other five patients the planned liver procedure was abandoned. Two of these five patients were cirrhotic--in one of them an additional metastasis was seen, and in the other there was tumour invasion of the portal vein. Of the three noncirrhotic patients, one had tumour invasion of the right hepatic vein, and the other two patients had additional metastases in the caudate lobe (Couinaud segment 1). Ultrasonography was found to be useful in 25% of patients who underwent this investigation during hepatic surgery--it avoided liver resections that would have failed because of advanced malignant disease.

Humans↗
PubMed1990

Cystosarcoma phylloides: calcified pulmonary metastases detected by computed tomography.

We report the appearance of calcifications on computed tomography (CT) images of pulmonary metastases from a rare breast tumor, malignant cystosarcoma phylloides. Histologic examination of the pulmonary masses revealed malignant spindle cells with osteoid and cartilage components in the cellular stroma. This appearance has not been described previously.

Aged↗