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Biomedical subjects

M Hartman

Publications and source records attributed to M Hartman.

At least 19 recordsLinked to original sources
PubMed1992

Platelet-derived growth factor and its receptors in human glioma tissue: expression of messenger RNA and protein suggests the presence of autocrine and paracrine loops.

The expression of platelet-derived growth factor (PDGF) and its receptors was analyzed in 14 gliomas of various degrees of malignancy and compared with three gliosis cases by in situ hybridization and immunohistochemistry techniques. Expression of both PDGF A- and B-chains was higher in glioblastomas than in astrocytomas. The PDGF A-chain mRNA was predominantly found in cell-rich areas in glioblastomas. The cognate PDGF-alpha receptor (PDGFR-alpha) mRNA was heterogeneously distributed in gliomas of all grades, and PDGFR-alpha expression was higher in gliomas than in gliosis. Within some glioblastomas probed with PDGFR-alpha complementary RNA, cells heavily loaded with grains were intermingled with others containing low or moderate signals. The heavily labeled cells were often found in the vicinity of proliferating capillaries. Immunostaining with an anti-PDGF antibody and an affinity-purified antiserum against the PDGFR-alpha showed strong staining of most tumor cells with both antibodies in glioblastoma. In addition, the PDGFR-alpha antibodies yielded a strong staining of scattered cells, and the anti-PDGF antibody yielded staining of a few cells within the astrocytoma. Furthermore, high levels of the PDGF-beta receptor (PDGFR-beta) and PDGF B-chain mRNA as well as the beta receptor protein were found in hyperplastic capillaries. These results suggest the presence of autocrine and paracrine loops in glioma, activating the PDGFR-alpha in glioma cells and the PDGFR-beta in endothelial cells.

Adolescent↗
PubMed1992

Ultrasound guided needle biopsy of brain tumors using an automatic sampling instrument.

All ultrasound (US) guided needle biopsies of brain tumors performed during an 8-year period were reviewed. Tissue samples were obtained in 112 of 115 biopsy procedures, and a histologic diagnosis was established in 99 cases (88.4%). The rate of major complications was 8.0%. The mortality is similar as in reports on stereotactic and CT-guided biopsy procedures while the morbidity is higher in our material. There are no large series available on US guided intracranial biopsy with adequate reports of complications. A modified biopsy technique is introduced here using a cutting needle and an automatic sampling instrument. The modified technique, which has been used in all cases since 1985, yielded diagnostic material in 91.5%. This method consistently provides a tissue core which is essential for a confident histopathologic diagnosis.

Biopsy, Needle↗
PubMed1991

The use of semantic knowledge in Alzheimer's disease: evidence for impairments of attention.

The ability to access and use semantic knowledge was examined in 25 patients with Alzheimer's disease (AD) and 31 healthy controls. The AD patients exhibited intact automatic activation of semantic relationships on a semantic priming task. They also made active use of category information on a recognition memory test. However, the patients did not use semantic information to generate expectations on the semantic priming task and were inconsistent in their use of category information on the memory test. It is suggested that attentional deficits underlie the observed impairments and may in fact help explain the patterns of performance across tasks differing widely in their overt cognitive demands.

Adult↗
PubMed1991

Aging and suppression: memory for previously relevant information.

In the 1st part of the experiment, older and younger adults read a series of high-cloze sentence frames, each missing its final word (e.g., "She ladled the soup into her____."). Subjects were instructed to predict the ending for each. For critical sentences, the predicted final word (bowl) was not shown. Instead, an unexpected but acceptable ending (lap) was provided as the target. On a subsequent indirect memory test in which subjects generated endings to medium-cloze sentences, older adults showed reliable retention of both the disconfirmed (bowl) and target (lap) endings. Younger adults showed retention of only the targets. Results are consistent with the Hasher and Zacks (1988) view that the impaired inhibitory mechanisms of older adults impede the abandonment of no-longer-relevant thoughts.

Adolescent↗
PubMed1991

Train versus pedestrian accidents.

Railroad-related trauma has been associated with injuries causing considerable morbidity. This is a retrospective study of 15 consecutive patients who were run over by trains. The initial injury produced a traumatic amputation of 10 extremities in eight patients. Limb salvage in two other patients with severe fractures failed, and subsequent lower extremity amputation was required. Despite efforts to salvage the most distal tissue possible, 8 of 12 extremities amputated in the acute traumatic period required revision to a more proximal level. Alcohol ingestion was involved in 13 of the 15 incidents in the study. No patient received posthospitalization alcohol rehabilitation. In addition, despite the young age of the patients in this series, only one patient was rehabilitated to a prosthetic ambulator.

Accidents↗
PubMed1990

A study of the inhibition of adrenaline-induced vasoconstriction in the isolated perfused liver of rabbit.

We have studied the action of a series of vasoactive and antispasmodic agents on the intrahepatic vasoconstriction induced by adrenaline in the isolated perfused liver of rabbits. The arterial and portal venous resistance, oxygen consumption, liver weight and bile flow were investigated. The drugs used were as follows: nonspecific alpha-adrenergic antagonists (DH-ergocristine, dibenamine, phenoxybenzamine), vasodilators with a direct miscellaneous action (theophylline, papaverine, dipyridamole, glucagon, Aiu-cor by Instituto Gentilli, Italy [inosine, ATP, IPI, UTP]) and antispasmodics (piperylone, tropenziline, noraminophenazone). Adrenaline increased arterial and portal venous resistance followed by a diminution of oxygen consumption, liver weight and bile flow. alpha-Adrenergic antagonists inhibited the effects of adrenaline on portal venous resistance and oxygen consumption and especially the effects on hepatic arterial resistance. The most potent agent was phenoxybenzamine. In contrast to alpha-adrenoceptor blockade, the effects of other vasoactive agents were without a sustained influence on hepatic arterial resistance (excepting those of glucagon and dipyridamole). Some of them were effective as antagonists on responses in the portal venous bed (papaverine, Aiu-cor). Moreover, there were drugs exerting an enhancement of the vasoconstrictor responses of hepatic artery to low concentrations of adrenaline with no effect on the portal venous bed (piperylone, tropenziline). Theophylline and noraminophenazone exerted no effect either on the arterial or portal venous bed. No vasodilator agent antagonized the changes of the bile flow after adrenaline administration.

Animals↗
PubMed1990

Delineation of gliomas with magnetic resonance imaging using Gd-DTPA in comparison with computed tomography and positron emission tomography.

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I-II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.

Adult↗
PubMed1989

Explicit and implicit remembering: when is learning preserved in amnesia?

Amnesic patients can learn and retain a variety of skills. To investigate what distinguishes tasks that are within the learning abilities of amnesic patients from those that are not, we administered two tests to individuals with Korsakoff's syndrome and two control groups. One was a visual reaction time task with an embedded repeating sequence of stimulus positions. Response times of Korsakoff patients indicated that they learned this sequence and retained it normally for a week. The second task was a tactual stylus maze in which all blind alleys were blocked. Korsakoff patients were impaired in learning this maze, as assessed by the time required to trace it. Differences between the two tasks are outlined and the implications of these differences are discussed.

Adult↗
PubMed1989

Implicit learning of new verbal associations.

Implicit learning of a series of new verbal associations was studied in four experiments. The first two experiments demonstrated that learning of a repeating sequence of verbal stimuli may occur without awareness, but only when the stimulus-response mapping requires an attention-demanding activity: Subjects who were unaware of the sequence learned when instructed to categorize the stimuli, but not when instructed simply to read them. However, in both situations, unaware subjects performed no better than untrained control subjects in expressing their knowledge of the sequence explicitly. In Experiments 3 and 4, subjects showed implicit learning when the task involved either motor responses to verbal stimuli or verbal responses to spatially arranged stimuli. These findings are discussed in terms of the conditions under which implicit learning can be obtained. First, they demonstrate implicit learning of a set of new associations in the verbal domain. Second, the data suggest that attention is important in implicit learning. Finally, the degree of interitem organization that is familiar preexperimentally seems to partially determine the amount of implicit learning.

Adult↗
PubMed1989

Complications of intracranial pressure monitoring in trauma patients.

A retrospective review of 175 intracranial pressure (ICP) monitors placed in 140 trauma patients over a recent 3-year period showed a 10.3% infection rate. Factors that were related to the development of an ICP monitor-related infection included: 1) duration of monitoring; 2) requirement for serial monitors; and 3) concurrent infection at other sites. These findings are discussed in light of the related literature concerning ICP monitoring and recommendations made to decrease the incidence of infection-related complications.

Adult↗
PubMed1988

Myocardial protection with blood cardioplegia in ischemically injured hearts: reduction of reoxygenation injury with allopurinol.

Myocellular injury mediated by oxygen radicals potentially limits myocardial protection in ischemically damaged hearts. This damage may be greater with oxygen-carrying blood cardioplegic solutions. A major mechanism of oxygen radical production is the conversion of hypoxanthine to uric acid by xanthine oxidase. In 16 anesthetized dogs, we studied whether adding allopurinol, a xanthine oxidase inhibitor, to blood cardioplegia would improve recovery of left ventricular (LV) performance and oxygen consumption. Millar transducer-tipped catheters and minor axis ultrasonic crystals were placed to assess LV performance by the slope of the end-systolic pressure-minor axis diameter relationships (Emax). Following total vented bypass, the hearts underwent 30 minutes of normothermic ischemia and then hypothermic blood cardioplegia with 1 mM allopurinol (N = 8) or without allopurinol (N = 8). Postischemic LV performance was significantly better with allopurinol than without (49.5 +/- 8.0 versus 17.4 +/- 4.1% of preischemic Emax; p less than 0.004). Postischemic LV oxygen consumption in the beating working state, calculated from LV blood flow (15 microm microspheres) and oxygen extraction, was comparable to preischemic values with and without allopurinol (10.2 +/- 1.2 versus 8.6 +/- 1.2 ml O2/100 gm/min). We conclude that allopurinol enhancement of blood cardioplegia increases myocardial protection in severely ischemic ventricles.

Allopurinol↗
PubMed1988

Malignant prolactinoma with multiple intracranial metastases studied with positron emission tomography.

A rare case of a patient with multiple intracranial metastases from a prolactin-secreting pituitary neoplasm is described. At the age of 14 years, the patient had been operated on for a sellar tumor; he presented 12 years later with severe headache, at which time computed tomographic and magnetic resonance imaging scans revealed multiple intracranial metastases. Histopathology examination showed pituitary neoplastic cells with positive immunostaining for prolactin. The patient was investigated with positron emission tomography (PET) and dopamine D2-receptor binding, and the amino acid metabolism of the tumor was characterized in vivo. High dopamine D2-receptor binding and high amino acid metabolism were found in the tumor. The patient was subsequently treated with bromocriptine injections that resulted in a decrease in serum prolactin levels, decreased dopamine D2-receptor binding, reduced amino acid metabolism, and a reduction in tumor volume. This case demonstrates a beneficial effect of bromocriptine treatment in a patient with prolactinoma with multiple intracranial metastases. It also illustrates the great potential of PET in the in vivo characterization of the D2-binding and the high sensitivity of 11C-labeled L-methionine in the follow-up of treatment in patients with pituitary adenomas.

Adenoma↗