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Biomedical subjects

D Hunter

Publications and source records attributed to D Hunter.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

MRI-guided biopsy of bone in a hybrid system.

This is a report of our experience with percutaneous, MRI-guided biopsies in 25 patients with skeletal lesions using a 1.5-T MR hybrid system. Twenty-five consecutive patients with skeletal lesions were referred for MRI-guided biopsy. Biopsies were performed with a 1.5-T Philips Gyroscan (Philips Medical Systems, Best, The Netherlands) combined with a c-arm fluoroscopy. Specimens were obtained percutaneously either with a 14- or 18-gauge "side-slit" type of biopsy needle (n = 10 skeletal lesions that had penetrated through the cortex), or using a prototype coaxial drill system powered either by hand or an optional motor (n = 15 skeletal lesions still covered with cortical bone). All but two biopsies could be completed within the MR unit. For one patient, who required a transpedicular approach to a lumbar vertebra, and for one child, who required general anesthesia, we decided to switch to CT guidance. In 19 of the 25 cases (17 of the 23 cases performed in MR), the sample was sufficient and the histopathologic diagnosis was confirmed. Three patients had an inadequate sample, and three others had adequate samples but inaccurate results. No procedural complications occurred. Percutaneous biopsy of skeletal lesions performed under MRI-guidance was found to be safe and reasonably accurate. There were no procedural complications in our small series. MRI may be used as an alternative to CT, but its role vis-à-vis CT has yet to be ascertained.

Biopsy, Needle↗
PubMedDate not supplied

Percutaneous intravascular biopsy using a Simpson atherectomy catheter: technical note.

The design of the Simpson atherectomy catheter makes this device a potentially safe and technically easy tool to obtain adequate pathologic intravascular or intraluminal specimens. The risk of perforation should be low, but this use has to be further studied. We describe the first intravascular biopsy performed with the Simpson catheter.

Arteriosclerosis↗
PubMedDate not supplied

Hepatic mesenchymal hamartoma in a neonate: a case report and review of the literature.

To describe an unusual presentation of mesenchymal hamartoma in a critically ill neonate necessitating a novel therapeutic embolization before definitive resection. An unusual presentation of a large hepatic mass in a newborn complicated by pulmonary hypertension and vascular "steal" with renal insufficiency is presented. The mass was initially successfully embolized, but then revascularized, necessitating resection in an attempt to improve the clinical status of the critically ill neonate. The resected mass was a mesenchymal hamartoma with a necrotic center and extensive arterial collateralization. The patient began improving immediately after resection. Mesenchymal hamartoma may present in the neonate as a diagnostic dilemma. This is the first case report describing persistent pulmonary hypertension and renal compromise from this tumor. Embolization as a therapeutic modality to address this tumor is described. The cause of the persistent and severe pulmonary hypertension remains unclear,but may be related to the tumor.

Acute Kidney Injury↗
PubMedDate not supplied

The effect of nicardipine on neuronal function following ischemia.

In cerebral ischemia, it has been proposed that calcium influx into neurons results in irreversible cellular injury during reperfusion. We administered nicardipine, a dihydropyridine calcium entry blocker, by continuous subcutaneous infusion to twenty five rats beginning before (PR) or following (PO) ischemia, and compared somatosensory evoked potentials (SEPs) to twenty eight ischemic control animals. Comparable ischemic cellular changes were seen in the hippocampi of all animals. SEP amplitude was higher in both the PR (p less than .005) and PO (p less than .0005) groups compared to controls. This effect was found in all three components (P1, N1, P2) of the evoked response. Plasma nicardipine levels of 6-10 ng/ml were associated with mild hypotension. We conclude that nicardipine improved neuronal function as measured by SEPs when administered before or after ischemia, most likely by interrupting the cytotoxic events occurring in cortical neurons during reperfusion.

Animals↗
PubMedDate not supplied

Detection of middle ear disease in cleft-palate patients.

A prospective study of 17 cleft-palate patients under the age of 37 months was performed. The otoscopic findings, as reported by the primary physician and otolaryngologist, were compared with the results of tympanometry. Preoperatively, all tympanograms were abnormal. Ears with an AS pattern were not described as abnormal by any physician, and postoperatively, these ears all progresses to a more advanced stage of disease.

Acoustic Impedance Tests↗
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Sinus histiocytosis with massive lymphadenopathy.

A 22-month-old child presented with massive cervical adenopathy accompanied by a retropharyngeal mass that caused stridor and dysphagia. Biopsy from both sides was consistent with sinus histiocytosis with massive lymphadenopathy (SHML). SHML is an unusual benign lesion that characteristically presents with painless, massive cervical adenopathy. Extranodal sites such as orbit, nose and skin are usually affected in association with cervical adenopathy. The pharyngeal involvement in this and several other recently reported cases adds to the heterogeneity of presentation of this unusual disease. The etiology remains unknown. No treatment is required, nor is any treatment known to be consistently effective. Gradual resolution of adenopathy over six months to several years is the expected outcome.

Humans↗
PubMedDate not supplied

Chronomes, time structures, for chronobioengineering for "a full life".

Week-long or longer monitoring of blood pressure and heart rate, coupled to time-structure analyses, can help detect disease-risk elevations, as a warning of the need for a preventive prehabilitation. Within the normal range of physiologic variation, computer methods quantify time structures, or chronomes, that can serve as reference values. The major applied purpose for mapping chronomes is the detection of disease-risk syndromes such as blood pressure "overswinging" and heart rate "underswinging." Too much blood pressure variability (circadian hyperamplitude tension; CHAT), is a risk factor for vascular disease. Other risk syndromes are chronome alterations of heart rate variability (CAHRVs), consisting of a loss of "jitter", i.e., a reduced standard deviation of heart rate or of alterations in the spectral element of the heart-rate-variability chronome, such as in the correlation dimension, an endpoint of deterministic chaos. These alterations can again serve for prehabilitation. On the basic side, the spectral element of the heart-rate-variability chronomes extends from focus on the heartbeat's period of about 1 second to periods in heart rate and its standard deviation that are numerical equivalents of about 10.5- and about 21-year cycles of solar activity. A seemingly unnatural physiologic rhythm or pattern (such as one of 81.6 hours) may correspond numerically to a purely physical environmental rhythm. For example, interplanetary magnetic storms, with their cycles as external chronome components, trigger myocardial infarctions, strokes, and traffic accidents. The systematic monitoring of external rhythms along with physiologic ones for the concurrent analysis of rhythms with longer and longer periods could detect alterations anywhere in and between the 1 cycle/sec and the 1 cycle/10.5- or 21-years regions of the spectrum. Chronobiomimetic engineering for discovering both instantaneous and long-term chronorisk alterations can provide warnings of increased risk. If risk-lowering therapy is then instituted automatically, instrumented health care will be extended beyond the pacemaker-cardioverter-defibrillator, which focuses on the frequency of 1 cycle/sec. Instrumentation that automatically detects blood pressure that varies too much and heart rate that varies too little is needed for prompting prophylactic CHAT and CAHRV treatment. A database of reference values that can be used for chronodiagnosis is now accumulating.

Accidents, Traffic↗
PubMedDate not supplied

Differences in perinatal transmission among human immunodeficiency virus type 1 genotypes.

OBJECTIVE: To determine whether genotypes from human immunodeficiency virus type 1 (HIV-1) subtypes A, C, or D or intersubtype recombinants have the same probability of being transmitted from mother to child. METHODS: We determined the HIV-1 genetic subtype and maternal risk factors of 51 matched transmitting and nontransmitting mothers from Tanzania. The HIV-1 gag (p24-p7) and env (C2-C5) nucleotide sequences were used for genotype classification, and matched logistic regression analysis was used to assess differences among genotypes. RESULTS: Mothers infected with HIV-1 subtype A (odds ratio, 3.8; 95% CI, 0.8-24.7%), HIV-1 subtype C (odds ratio, 5.1; 95% CI, 1.3-30.8%), or HIV-1 intersubtype recombinant viruses (odds ratio, 5.3; 95% CI, 1.2-33.4%) were more likely to transmit HIV-1 to their infants than mothers infected with HIV-1 subtype D. Lower CD4 cell counts at enrollment were associated with transmission, but CD4 cell counts within each genotype did not explain differences in transmission among HIV-1 genotypes. CONCLUSION: We have shown that HIV-1 genotypes might be associated with differential risk for vertical transmission. These findings provide the first evidence that HIV-1 genetic subtypes may play a role in rates of vertical transmission in an African setting.

Base Sequence↗