Search PubMed⌕ Search

Biomedical subjects

J C Hoffman

Publications and source records attributed to J C Hoffman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Parotid masses: MR imaging.

Twenty patients with surgically proved neoplasms of the parotid gland were evaluated in order to compare contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging. In 14 patients both CT and MR imaging examinations were performed, while in six only MR imaging was performed. Because contrast resolution is better with MR imaging, it appears to be superior to CT in distinguishing the parotid gland from surrounding structures. Four intraparotid lesions were more conspicuous on T2-weighted MR images than on CT scans. MR imaging appears to be superior to CT for evaluating parotid masses and for distinguishing neoplasms of the parotid gland from those originating within the parapharyngeal space.

Adenoma↗
PubMed1987

MR imaging of pituitary adenoma: CT, clinical, and surgical correlation.

Twenty-five patients with suspected pituitary adenoma were evaluated prospectively with CT and MR. Nine patients underwent transsphenoidal surgery, and three of these showed a documented decrease in size of mass on bromocriptine therapy. CT was more sensitive than MR for detecting focal lesions (seven vs three) and sellar-floor erosion (12 vs six). MR was superior to CT in identifying infundibular abnormalities (seven vs six), focal abnormalities of the diaphragma sellae (10 vs seven), cavernous sinus invasion (four vs two), and optic chiasm compression (six vs zero). Thus, MR may be the procedure of choice for optimal identification and localization of macroadenoma. For patients with suspected microadenoma, however, this preliminary series indicates that CT remains the radiographic procedure of choice.

Adenoma↗
PubMed1986

Sinus pericranii. A case report.

A 7-month-old male presented with a 2 X 3 cm soft tissue mass overlying the right mastoid bone. An underlying bony defect was palpable. Plain skull films, CT scan and cerebral arteriogram showed the classic radiologic findings of a sinus pericranii. This rare vascular anomaly is briefly discussed.

Cranial Sinuses↗
PubMed1986

The transformation-related protein p53 is not bound to the SV40 T antigen in BALB 3T12 cells expressing T antigen.

In most murine cells transformed by the SV40 virus, virtually all of the cellular phosphoprotein p53 is in a complex with the SV40 T antigen. Here, we report that, in SV40-infected T-antigen-positive Balb 3T12 mouse cells, most (approximately 80%) of the p53 is not in complex. Complex formation was determined by measuring the amounts of [35S]methionine-labeled p53 which coprecipitated with T antigen when using monoclonal antibody to T antigen. The amount of complex formation was expressed as a percentage of total p53 present, measured by the amount of p53 precipitated with the monoclonal antibody to the p53. The values were confirmed by Western blotting procedure, in which the steady-state levels of the proteins were measured. In these measurements after complete precipitation with antibody to T antigen, the residual p53 in the supernatant was precipitated by antibody to p53, and this amount was denoted as free p53. There was no significant difference seen between the [35S]methionine-labeled tryptic peptides of complexed and the free p53 (or between complexed and free T antigens) as determined by two-dimensional gel electrophoresis and chromatography. Virus rescue experiments and retransformation by the rescued virus showed that there was no mutation in the SV40 DNA coding for the T antigen which could account for the lack of complex formation. Both p53 and T antigen were underphosphorylated in cells which exhibited reduced complex formation. Tumorigenicity in syngeneic mice and anchorage-independent cell growth in culture of various cloned mouse cells with or without T antigen expression was compared. The changes in the biologic properties were explainable solely on the basis of known or expected effects of expression of the T antigen and were independent of complex formation or of absence of complex formation between p53 and T antigen.

Animals↗
PubMed1986

CT evaluation of effects of cranial radiation therapy in children.

A retrospective evaluation was completed of 49 children who received conventional cranial radiation therapy for primary central nervous system and/or skull-base neoplasia and who had follow-up CT studies. In these children, abnormalities in normal parenchyma away from the tumor itself were surprisingly frequent, with or without chemotherapy. Generalized volume loss or atrophy was the most frequent abnormality (51%), but in this population it may have resulted from a variety of causes. Calcification in nontumorous parenchyma was common (28%) with or without chemotherapy. The most frequent site of calcification was subcortical at the gray-white junction. Calcification was progressive over 1-2 years and correlated pathologically with mineralizing microangiopathy and dystrophic calcification with demyelination. White-matter abnormalities other than those associated with shunt malfunction and tumor edema occurred in 26% of the patients. Both white-matter abnormalities and calcification occurred predominantly in younger children, particularly those under 3 years old at the time of radiation therapy. Of the 21 children who received chemotherapy in this series, only two received methotrexate. White-matter abnormalities and calcifications occurred with similar frequency in children with and without chemotherapy; thus, radiation therapy is the most likely cause of these findings.

Adolescent↗
PubMed1985

The use of transarterial microembolization in the management of hemangiomas of the perioral region.

The management of oral and perioral hemangiomas depends on several clinical factors. Surgery of these benign lesions can at times be disfiguring, especially when the lips, muscles, or the maxilla and mandible are involved. In addition, by the very nature of these lesions, surgical treatment may be associated with excessive intra- and perioperative blood loss. A series of five patients who had hemangiomas in the perioral region and who were initially treated with transarterial microembolization, preoperatively in two cases and as the only treatment in three cases, is presented. The technique of microembolization is described and recommendations for its use are given.

Adolescent↗
PubMed1985

Fertility control in the bitch by active immunization with porcine zonae pellucidae: use of different adjuvants and patterns of estradiol and progesterone levels in estrous cycles.

To determine the changes in patterns of 17 beta-estradiol and progesterone levels underlying abnormal cycles in bitches immunized with solubilized crude porcine zonae pellucidae (cPZP), to attempt to circumvent these problems by immunizing with a purified zona fraction (pPZP), and to test the effectiveness of different adjuvants, bitches were immunized with cPZP or pPZP 2-6 times with no adjuvant, Freund's adjuvant, alum adjuvant, or the adjuvant CP-20,961. The bitch immunized without adjuvant had a low titer with a normal cycle and fertility. Immunization with cPZP and adjuvant produced moderate to high titers of antizona antibodies and infertility. Bitches with high titers experienced abnormal estrous cycles. Estradiol rose during proestrus, but instead of falling sharply in early estrus as in controls, it remained elevated. Progesterone did not rise. The moderate-titered bitches had normal cycles and steroid patterns. Bitches immunized with pPZP had moderate titers. Cycles were normal after 3 injections, but after 6 injections one bitch had an abnormal cycle. One pPZP-immunized bitch remained fertile but the others were infertile. Alum was the mildest adjuvant, causing no injection site lesions, but the highest titers occurred with Freund's and CP-20,961 adjuvants. All three adjuvants induced titers sufficient to inhibit fertility. Infertility in bitches immunized with PZP may be due to prevention of zona penetration, because their antisera inhibited zona penetration of oocytes by spermatozoa in vitro. However, alterations in ovarian function preventing ovulation and luteinization could be involved in high-titered bitches.

Adjuvants, Immunologic↗
PubMed1985

Jugular venous thrombosis: MR imaging.

Magnetic resonance (MR) imaging of jugular venous thrombosis was investigated in three patients who had symptoms suggestive of this condition; the diagnosis was later confirmed by computed tomography, by venography, and clinically. Bright intraluminal signal intensity was seen throughout the course of the affected jugular vein on MR images in all three patients, in sharp contrast to the lack of signal from the corresponding site in the uninvolved venous system. Temporal changes in signal intensity from the acute to subacute stage of thrombosis were evaluated for one patient. A relative increase in signal intensity for the subacute phase was believed to be related to a decrease in the T1 relaxation time. MR may be the imaging modality of choice in the investigation of venous thrombosis.

Adult↗
PubMed1985

Prolactin-secreting pituitary microadenomas: inaccuracy of high-resolution CT imaging.

Computed tomographic (CT) and surgical findings were correlated retrospectively in 51 patients with preoperative diagnoses of prolactin-secreting pituitary microadenomas. Thirty-nine had microadenomas at surgery. Twenty-three had identifiable discrete lesions. Of these, 21 had microadenomas and two did not; these two groups could not be distinguished reliably. Six patients with proven microadenomas had normal CT scans. Focal hypodense lesions, sellar floor erosion, infundibulum displacement, gland height greater than 8 mm, and an abnormal diaphragma sellae configuration are neither sensitive nor specific findings of microadenoma. A significant number of patients with proven microadenomas had few or none of these abnormalities. Thus, recognition of prolactin microadenoma may not be possible by CT alone, even with high-resolution direct coronal imaging.

Adenoma↗
PubMed1985

Contrast enhancement in CT differentiation between recurrent disk herniation and postoperative scar: prospective study.

Recurrent disk herniation and postoperative scarring are among the major causes of recurrent symptoms after surgery for lumbar disk disease. The myelographic differentiation between these two etiologies is, at best, difficult. To evaluate the role of intravenous contrast enhancement and its impact on making this differentiation using computed tomography (CT), 98 postoperative symptomatic patients were studied prospectively with this technique. Twenty-two patients had subsequent reexploration (23 disk spaces). The unenhanced and enhanced studies of these patients were interpreted independently without surgical information. With contrast enhancement, only three CT studies were considered indeterminate, whereas 10 studies without contrast enhancement were indeterminate. The overall correct diagnosis with contrast enhancement was 17 (74%) of 23, while only 43% of the unenhanced studies yielded the correct diagnosis. Therefore, intravenous contrast enhancement significantly increased the diagnostic accuracy and level of confidence in making the differentiation between recurrent herniated disk and scar.

Cicatrix↗
PubMed1984

Pitfalls in the computed tomographic evaluation of the lumbar spine in disc disease.

Computed tomography (CT) is an effective non-invasive method of evaluating the lumbar spine in cases of suspected disc disease. In over a 3-year period in a high volume neuroradiologic practice we have observed a number of pitfalls in the diagnosis of herniated nucleus pulposus which may lead to erroneous conclusions and therefore, decrease the overall accuracy of the examination. These pitfalls, and their implications are presented and discussed.

Humans↗
PubMed1984

Gas computed tomographic cisternography: evaluation of small and intracanalicular acoustic neuromas.

With improvements in microsurgical techniques, early evaluation of small and intracanalicular acoustic neuromas has taken on added importance. Since its introduction in 1979 by Sortland, several authors have demonstrated the accuracy and safety of computed tomography combined with gas cerebellopontine angle cisternography in the early diagnosis of acoustic neuromas. We present our experience with 32 patients referred for gas computed tomographic cisternography yielding five surgically proved acoustic neuromas, three of which were less than 1 cm in size. This procedure can be performed on an outpatient basis, has a low morbidity, and is highly accurate in diagnosing even purely intracanalicular tumors. Gas computed tomography cisternography offers several advantages over positive contrast cisternography, and is the procedure of choice in the radiologic diagnosis of acoustic neuromas after contrast-enhanced computed tomography has excluded the presence of a large tumor.

Cerebellopontine Angle↗
PubMed1984

Imaging in inflammatory disease of the kidney.

The evaluation and management of patients with severe persistent urinary tract infection after appropriate antibiotic therapy can be difficult. The first radiologic examination is usually excretory urography, but the findings often are nonspecific. A group of 40 patients was studied to assess the contribution of cross-sectional imaging and included patients with diffuse and focal pyelonephritis, renal abscess, pyonephrosis, and pararenal abscess. Indications for cross-sectional imaging include persistent symptoms despite antibiotics, predisposing "risk factors," suspicion of flank mass on other imaging methods, and no excretion on urography. Percutaneous aspiration and/or drainage for diagnosis and/or treatment can be guided by the cross-sectional imaging methods.

Abscess↗
PubMed1984

Clinical and pathological effects of bromocriptine on prolactin-secreting and other pituitary tumors.

Bromocriptine inhibits prolactin secretion and causes size reduction of prolactin-secreting adenomas. The effect of the drug upon pituitary tumors other than prolactinomas is uncertain. The authors report a prospective series of 12 patients with pituitary macroadenomas in whom bromocriptine was administered for 6 weeks prior to transsphenoidal surgery. Five of the patients had computerized tomographic documentation of significant reductions in tumor size (Group A) and six had no change (Group B) during 3 and 6 weeks of bromocriptine administration. One patient who demonstrated size reduction in his tumor was not assigned to either group as he was treated with high-dose dexamethasone concurrently with the bromocriptine. Pathological examination (light and electron microscopy and immunocytochemistry) indicated that all Group A patients harbored tumors with prolactin granules whereas all Group B tumors lacked such granules. Adenoma cells in the responsive tumors were involuted with reduced cytoplasmic, nuclear, and nucleolar areas. Neither widespread cell necrosis, infarction, nor vascular injury was observed. Two of the five Group A patients discontinued bromocriptine prior to completion of the 6-week protocol and had a rapid return of their tumors to pre-treatment size. Although bromocriptine has been reported to cause shrinkage of nonfunctional tumors, there was no radiological evidence of size reduction or pathological changes in the nonfunctional tumors of this series. Interestingly, serum levels of prolactin were modestly elevated (84 and 113 ng/ml) in two of the six Group B patients, an elevation due to stalk compression rather than secretion by adenoma cells. This finding underscores the fact that failure of bromocriptine to reduce pituitary tumor size in the presence of hyperprolactinemia may occur because the tumor is other than a prolactinoma. This is the first moderate-sized group of patients in whom pathological changes in responsive prolactinomas during bromocriptine therapy have been demonstrated. As bromocriptine is not tumoricidal, and thus not curative, there is insufficient evidence to recommend this drug as primary therapy for either prolactin-secreting or nonfunctional macroadenomas, but the drug may have potential as a preoperative adjunct to effect shrinkage of prolactinomas and theoretically, at least, make excision easier and possibly more complete.

Adenoma↗
PubMed1984

Use of cyclopropane to test generality of anesthetic requirement in the elderly.

The minimum alveolar concentration (MAC) of cyclopropane was determined in young (mean age, 32 yr; n = 16) and older (mean age, 81 yr; n = 12) surgical patients. Cyclopropane requirement was 23% lower in the elderly (P less than 0.01). This reduction in anesthetic requirement with age is similar to that reported previously for halothane and isoflurane and supports the thesis of a general effect of age on anesthetic requirement.

Adult↗