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G B Seibert

Publications and source records attributed to G B Seibert.

10 recordsLinked to original sources
PubMed1989

Left ventricular coordinate systems.

Three-dimensional kinematics of radiopaque markers in anterior, posterior, septal, and lateral regions of a major equatorial plane were evaluated in anesthetized dogs by biplane fluoroscopy. Stationary coordinate systems measured marker locations recorded during diastole and systole from a contractile origin at the center of contraction at end systole and from a geometric origin at the intersection with the equatorial plane of the ventricular long axis at end diastole. A time-indexed system measured marker locations at end diastole and at end systole, respectively, from the locations of the geometric origin at end diastole and end systole. Compared to the stationary system with the geometric origin, both the stationary system with the contractile origin and the time-indexed system reduced the variability of the radial components of the contractile displacements between ventricular regions. In contrast to the other two systems, the system with the contractile origin reduced circumferential components to values not significantly different from zero. These results indicate that 1) abnormally contracting regions of the ventricle may be located and their size measured by determining the region where the radial component differs from that in the rest of the equatorial plane and 2) rotation in a major equatorial plane of the ventricle is significant, but the influence of rotation can be minimized by referencing ventricular dimensions to a coordinate system with an origin at the center of contraction.

Animals↗
PubMed1989

Intracranial arteriovenous malformation: relationship between clinical factors and surgical complications.

Serious morbidity and hyperemic states continue to complicate the treatment of certain intracranial arteriovenous malformations (AVMs). Clinical and radiographic characteristics of 62 patients treated over 3 years were analyzed to determine if hyperemic complications (HCs) (defined as unusual perioperative edema or hemorrhage) and outcome could be predicted. Twenty-five (40%) of the patients were less than 30 years old, 28 (45%) were between 30 and 50, and 9 (15%) were more than 50. A history of hemorrhage was found in 48%, and 34% presented with progressive deficits. Thirteen (21%) developed evidence of HCs; 51 (82%) ultimately had a good outcome, 4 (6%) had a poor outcome, and 7 (11%) died. The incidence of HCs was higher in patients whose AVMs recruited perforating vessels (53%) than those without (7%) (P less than 0.001). The presence of preoperative angiographic steal carried a 35% risk of HCs whereas its absence carried a 13% risk (P less than 0.05). The sum of the diameters of the feeding vessels was also predictive (P less than 0.05). Outcome was clearly age-related: good outcome was achieved in 92% of the patients less than 30 years old, 86% of those 30 to 50, and 44% of patients older than 50 (P less than 0.05). Left hemispheric AVMs showed less morbidity than right (P less than 0.05) as did those without perforating vessel recruitment (P less than 0.07). HCs had a dramatic impact on outcome with 92% of patients without HCs having good outcome and 46% of those with HCs recovering well (P less than 0.001).

Adult↗
PubMed1989

Intracranial arteriovenous malformation: relationships between clinical and radiographic factors and cerebral blood flow.

Arteriovenous malformations (AVMs) dramatically alter normal cerebral circulatory dynamics. Clinical and radiographic data from 62 patients were analyzed to determine their impact on total brain blood flow (TBF) measured by single-photon emission computed tomography. 48% of patients presented with hemorrhage and 34% with progressive deficits. 37% had angiographic steal and 21% developed postoperative hyperemic complications. 40% were under 30 years old, 45% were between 30 and 50 years of age, and 15% were over 50. TBF was less than 70 ml/100 gm/min in 32% of patients, between 70 and 84 ml/100 gm/min in 40%, and greater than 84 ml/100 gm/min in 27%. Female patients had higher TBF than males; 42% of females but only 17% of males had values greater than 84 ml/100 gm/min (p less than 0.05). A trend toward decreased TBF with advancing age was noted. Intracranial hemorrhage was associated with lower TBF; 47% of patients with hemorrhage and 19% of those without had TBF of less than 70 ml/100 gm/min (p less than 0.05). 89% of patients with AVMs less than 5 cm in diameter had TBF of less than or equal to 84 ml/100 gm/min, and 65% of those with larger AVMs had similarly low flows (p less than 0.05). A trend toward lower TBF was observed in patients with unfavorable outcomes.

Adult↗
PubMed1989

Intracranial arteriovenous malformation: contralateral steal phenomena.

Sixty-two patients with radiographically proven intracranial arteriovenous malformations underwent preoperative regional cerebral blood flow measurement with 133Xe single-photon emission computed tomography. Contralateral regions of hypoperfusion were detected in all cases. Steal severity was assessed according to the contralateral steal index [ISteal(c)]. ISteal(c) was greater than 0.7 (severe) in 22 (35%), 0.7-0.8 (intermediate) in 18 (29%), and greater than 0.8 (mild) in 22 (35%). ISteal(c) was more frequently severe or mild in females and more often intermediate in males (p less than 0.05). Hyperemic complications were encountered more frequently in patients with intermediate ISteal(c) (p = 0.086). An unfavorable outcome was associated with less severe contralateral steal (p = 0.12). A detailed clinical, radiographic, and hemodynamic profile may help to preoperatively identify patients at high risk for a poor surgical outcome.

Adult↗
PubMed1988

Acoustic analysis of affective prosody during right-sided Wada Test: a within-subjects verification of the right hemisphere's role in language.

A within-subjects study of the affective characteristics of voice was carried out in patients undergoing a Wada Test (WT). All patients became densely aphasic after the left-sided WT and lost the ability to impart affect into speech after the right-sided WT. The affective changes in voice induced by the Wada test were acoustically analyzed by computer-assisted techniques and compared to data obtained pre-Wada and post-Wada. The statistical results, using a one-way analysis of variance for repeated measures, confirmed robustly the current view that the right hemisphere modulates dominantly the affective components of language. The results are also evaluated in light of recent clinical and acoustical data regarding the organization of language in speakers of tone languages, thus, allowing the authors to address issues concerning universal principles of brain-language-behavioral relationships.

Adult↗
PubMed1988

Intracranial arteriovenous malformation: relationships between clinical and radiographic factors and ipsilateral steal severity.

Intracranial arteriovenous malformations (AVMs) are high flow shunts that may jeopardize the perfusion of adjacent tissue. Clinical and radiographic data from 62 patients were analyzed to determine their relationship to the severity of steal measured by single photon emission computed tomography (SPECT). The ipsilateral steal index [ISteal(i)] was determined by dividing regional cerebral blood flow (rCBF) values within hand-drawn regions of hypoperfusion in the ipsilateral hemisphere by total brain flow, which was calculated as the average rCBF of each hemisphere. Of the patients, 40% were less than 30 years of age, 45% were 30 to 50 years old, and 15% were over 50. Forty-eight per cent presented with hemorrhage and 34% presented with progressive deficits. There was angiographic steal in 37%, and postoperative hyperemic complications developed in 21%. All patients had ipsilateral regions of hypoperfusion. The ISteal(i) was less than 0.7 in 23 (37%), 0.7 to 0.8 in 20 (32%), and greater than 0.8 in 19 (31%). The ISteal(i) was significantly less severe in the patients over 50; 78% of these patients had an ISteal(i) of greater than 0.8 (P less than 0.01). A history of hemorrhage was associated with less severe steal than that in patients who had not bled (P = 0.088). Patients presenting with a history of progressive deficits had increased severity of steal compared with those without progressive deficits (P less than 0.05). A trend toward decreased severity of steal was noted in patients with unfavorable outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Systematic investigation into interaction of ionizing radiation and doxorubicin in the Dunning R3327G prostatic adenocarcinoma model.

The interaction of doxorubicin and radiation has been systematically studied in the Dunning R3327G prostatic adenocarcinoma, the preeminent animal model for human prostatic cancer. Subcutaneous tumors (produced by injection of 10(7) cells) were treated when about 1 cm3 in volume (19-22 days postimplant). Each modality was used at 1 of 3 dose levels; 2, 4, and 9 mg/kg for doxorubicin; and 5, 15, and 25 Gy for radiation. Single treatment with each agent was combined, in both sequences and five delay times (0.5, 12, 24, 48, and 120 hr) between agents. Growth of individual tumors was fit to a quadratic exponential growth model which was solved for the growth delay and growth rate at twice initial volume. Analysis of variance identified significant interactions for doxorubicin and radiation (due to drug toxicity), sequence and delay, and sequence and radiation, in addition to the four factors individually. The effect on the tumor of combined doxorubicin and radiation is basically additive. Sequence and delay are important in overall tumor control.

Adenocarcinoma↗
PubMed1976

Prolongation of postoperative disease-free interval and survival in human colorectal cancer by B.C.G. or B.C.G. plus 5-fluorouracil.

83 patients with colorectal carcinoma of the Dukes' C class were randomised to receive postoperative adjuvant therapy with B.C.G. alone or in combination with oral doses of 5-fluorouracil (5-F.U.), and have been followed for up to thirty months. Results were compared with carefully selected historical controls who were treated by surgery alone. A statistically significant prolongation of both disease-free interval and overall survival was observed in 50 patients receiving the combination of B.C.G. and 5-F.U. (P=0.03, P=0.01 respectively) as well as in 33 patients receiving B.C.G. alone (P=0.03, P=0.05 respectively). The efficacy of B.C.G.+5-F.U. was independent of the number of tumour-involved lymph-nodes in the surgical specimen. In contrast, B.C.G. given alone appears to be highly effective among 10 patients with 6 or more positive lymph-nodes (P less than 0.04) and ineffective (as yet) among 23 patients with 5 or less positive lymph-nodes. These results suggest that adjuvant immunotherapy, with or without chemotherapy, can improve the prognosis of surgically treated patients with colorectal carcinoma of the Dukes' C class.

Administration, Oral↗
PubMed1975

Adjuvant immunotherapy and chemoimmunotherapy in colorectal cancer of the Dukes' C classification. Preliminary clinical results.

Fifty-eight patients with Dukes' C classification of carcinoma of the large bowel were placed on adjuvant immuno- or chemoimmunotherapy with Bacillus calmette guerin (BCG) or combination of 5-fluorouracil (5-FU) plus BCG following primary and definitive surgery, and were followed for up to 21 months. Of twenty-six patients receiving BCG alone by scarification, five have relapsed with 75% of freedom from disease estimated at 15.1 months compared with 10.1 months in a group of carefully selected historical controls who had surgery alone (p = 0.12). The survival of all patients receiving BCG alone has not reached the 75 percentile yet, and the difference from controls is currently estimated at the 18% level. The combination of 5-FU plus BCG (studied in 32 patients) may be superior to BCG alone at this time, in that it appears to more effectively protect against tumor recurrence (75 percentile not yet reached compared to control, (p = 0.08). The survival of patients on 5-FU plus BCG also appears to be improved (p = 0.09). No patients have expired compared to a 75 percentile survival of 16.6 months in the control. Serial determination of plasma CEA was crucial in the clinical follow-up of these patients. Frequent CEA detetminations have led to early detection of clinical relapse. In the elevation of CEA suggests tumor recurrence with a high degree of probability in patients with past history of cancer of the large bowel.

BCG Vaccine↗