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Biomedical subjects

J Patterson

Publications and source records attributed to J Patterson.

At least 91 records · Page 5Linked to original sources
PubMed1986

The dopamine withdrawal test following surgery for intracranial aneurysms.

Cerebral blood flow was measured in eight patients who were being treated with dopamine in order to maintain cerebral perfusion after the onset of delayed postoperative ischaemia following intracranial aneurysm surgery. Measurements were made whilst on treatment and repeated either during a reduction in the dosage or withdrawal of dopamine. There was a significant fall in cerebral blood flow in both hemispheres in all eight patients. Clinical deterioration was observed in seven of nine instances in which cerebral blood flow fell by 25% or more of the value while on dopamine treatment. There were no episodes of deterioration in six tests where the fall in cerebral blood flow was less than 25% of the starting value. It is suggested that cerebral blood flow measurement can be useful in predicting when it is safe to withdraw dopamine treatment in these patients. Hypertensive treatment should be maintained if a withdrawal test is associated with a fall in cerebral blood flow of 25% or more.

Adult↗
PubMed1986

Accuracy of stereotaxic localisation using MRI and CT.

The accuracy of stereotaxic coordinates determined using the Leksell apparatus with CT and MRI was investigated using an Agar filled head phantom. Both imaging techniques were found to produce an accuracy of better than 2 mm with the exception of the Z coordinate as measured by CT (2.3 mm). This latter error is greater because of the 3 mm slice width used. Direct coronal views were used to determine Z more accurately using MRI. The measurement procedures are described and it is shown that the Leksell system of using orthogonal coordinates enables the scaling of images, which is particularly necessary with MRI, to be done easily.

Humans↗
PubMed1986

Relative effectiveness of concurrent forward/backward versus simple forward and simple backward Pavlovian conditioning procedures.

Concurrent forward/backward Pavlovian conditioning procedures were compared with simple forward and simple backward procedures for differential excitatory and inhibitory conditioning. Four groups of dogs each received 30 shocks while restrained in a Pavlovian harness. One group of dogs (CON) received concurrent conditioning with a clicker signaling shocks and with a tone following shocks. For another group of dogs (SF), a clicker signaled the shocks, whereas the tone was randomly related to shocks. For a third group (SB), the tone followed shock termination, whereas the clicker was randomly related to shocks. For a fourth group (TRC), both the clicker and the tone were randomly related to shocks. All stimuli were then superimposed on a temporally paced avoidance baseline and their associative properties were assessed relative to the TRC group. Differential excitatory-inhibitory conditioning was significantly reduced in the concurrent procedure relative to that which occurred in the simple conditioning procedures despite exactly equal CS + -US and US-CS-contingencies. These results were interpreted with reference to contextual conditioning effects predicted by the Rescorla-Wagner conditioning model and the theoretical issue of independence vs. interdependence of CS-US associative strengths.

Acoustic Stimulation↗
PubMed1985

Valproate metabolite concentrations in brain increase with chronic administration of sodium valproate.

Rats were treated chronically with sodium valproate for varying periods of time up to eight weeks. A statistically significant negative correlation between plasma concentrations of valproate-derived substances (VDS) and length of treatment was observed while a statistically significant positive correlation was found between brain VDS concentration and length of treatment. Liver VDS concentrations showed a tendency to decrease with time but this trend was not statistically significant. A new procedure was developed to measure the tissue levels of VDS.

Animals↗
PubMed1985

Cerebral blood flow and CO2 responsiveness as an indicator of collateral reserve capacity in patients with carotid arterial disease.

Resting cerebral blood flow (CBF) and the response to inhalation of 7 per cent CO2 was measured in 74 patients with symptoms of cerebrovascular disease. In order to evaluate their role in the identification of patients with significant arterial lesions, these measurements were correlated with the angiographic appearances, the clinical picture and the presence or absence of infarction on CT scan. Patients with carotid stenosis of 60 per cent or more had normal resting flows, but reduced responsiveness to CO2 inhalation. Patients with carotid occlusion had both reduced resting flow and reduced CO2 responsiveness. Infarcts were visible in 25 per cent of the hemispheres studied, and were more common in patients with fixed neurological deficits, but were also present in 17 per cent of patients with transient ischaemic attacks (TIAs). Reduction in the collateral supply from the contralateral carotid artery via the Circle of Willis further reduced CO2 responsiveness with ipsilateral internal carotid occlusion. The normal increase in CBF which occurs with the inhalation of carbon dioxide is diminished with increasingly severe bilateral disease, with infarction and with a fixed neurological deficit.

Adult↗
PubMed1985

Specificity in the reactivation of infant memory.

In three experiments the specificity of an effective reactivation stimulus, or reminder, was examined. Two weeks after learning to produce movement in a crib mobile by footkicking, 3-month-old human infants showed no retention of the response-reinforcer contingency. A reactivation procedure 24 hours prior to the long-term retention test was effective if the reminder was a brief noncontingent exposure to the original 5-component training mobile or a mobile containing one novel substitution. When more than one novel component were substituted into the original mobile, the reminder was ineffective. This was predicted by the discrimination function 24 hours following training. A reminder containing only a single familiar (predictive) component and four novel ones was also moderately effective. In subsequent studies, we explored different interpretations of the reminder specificity effect. We hypothesize that reminder specificity is of particular adaptive value for developing organisms in providing a buffer against memory retrieval in inappropriate contexts.

Cues↗
PubMed1985

Effect of mannitol on cerebral blood flow and cerebral perfusion pressure in human head injury.

Patients with severe head injury frequently have evidence of elevated intracranial pressure (ICP) and ischemic neuronal damage at autopsy. Mannitol has been used clinically to reduce ICP with varying success, and it is possible that it is more effective in some types of head injury than in others. The aim of the present study was to determine the effect of mannitol on ICP, cerebral perfusion pressure (CPP), and cerebral blood flow (CBF) in patients with severe head injury, and to discover if these effects differed in different types of injury. Measurements of CPP, ICP, and CBF were made in 55 patients with severe head injury. In general, the resting level of CBF was higher in patients with diffuse injury (mean 50.2 ml/100 gm/min) than in those with focal injury (mean 39.8 ml/100 gm/min). Mannitol consistently reduced ICP and increased CPP and CBF by 10 to 20 minutes after infusion. The lowest flows (31.8 ml/100 gm/min) were recorded from the most damaged hemispheres of patients with focal injuries and elevated ICP. The baseline levels of flow did not correlate with ICP, CPP, Glasgow Coma Scale score, or outcome. Only four of the 55 patients had a CBF of less than 20 ml/100 gm/min in either or both hemispheres. The few low CBF's in this and other studies may reflect the steady-state conditions under which measurements are made in intensive care units, and that these patients have entered a phase of reperfusion.

Adult↗
PubMed1984

In situ study of T-cell subpopulations in cutaneous T-cell lymphoma. Diagnostic criteria.

The T-cell subpopulations present in skin biopsy specimens from 91 patients with cutaneous T-cell lymphoma (CTCL) and from 19 patients with benign lymphocytic infiltrates of the skin were examined in situ to define criteria for the differentiation of benign from malignant lymphocytic infiltrates. The monoclonal antibodies OKT 1 (pan T-cell), BE 3 (pan T-cell), OKT 4 (helper/inducer T-cell), OKT 6 (cortical thymocyte and Langerhans' cell), OKT 8 (suppressor T-cell), and OKT 10 (pan thymocyte) were used in direct or indirect immunoperoxidase reactions. Sections were examined at high magnification, and the distribution and percentage of cells reactive with each antibody were assessed. Three main patterns of staining were observed in the CTCL patients: (1) 64% of the biopsy specimens showed that 60% of the cells present in the dermis were T-cells that were OKT 1+ and BE 3+ and there was an even distribution of the different T-cell subpopulations, with 54% being OKT 4+ and 8% OKT 8+; (2) 21% patients showed selective loss of OKT 1 antigen, and 80% of these also showed loss of BE 3 antigen; and (3) 15% patients showed large numbers of OKT 8+ cells (range, 50%-90%) but the percentages of OKT 1+ and OKT 4+ cells were within the ranges seen in Group 1, indicating the presence of a population of T-cells simultaneously expressing OKT 4 (helper/inducer) and OKT 8 (suppressor) reactivity. In 95% of the CTCL patients, 3.5% OKT 6+ cells were present in the dermal infiltrate, and in 92% of patients, 3% OKT 10+ cells were present. Comparing sections from CTCL and benign dermatoses, no single diagnostic feature was identified, but helpful differentiating features were: (1) the even, rather than nodular, distribution of the T-cell subpopulation; (2) the selective loss of OKT 1 and BE 3 antigens; (3) the presence of T-cells simultaneously expressing OKT 4 and OKT 8 antigens; and (4) the presence of OKT 10+ cells.

Antibodies, Monoclonal↗
PubMed1984

S1-hypersensitive sites in eukaryotic promoter regions.

We have examined by fine mapping the S1 nuclease-hypersensitivity of the 5' flanking regions of the human beta-globin and rat preproinsulin II genes and of the SV40 origin/enhancer region. In all cases S1-hypersensitive sites are located in known or presumed promoter/regulatory regions. Though a consensus DNA sequence is not evident, all of these sites reside in predominantly homopurine-homopyrimidine stretches. The alternate (non-B) DNA structure which is revealed by the enzymatic probe is a sequence-dependent feature of a short stretch of DNA, which is retained upon transplantation into a foreign environment. The alternate structure exhibits S1-nicking patterns uniquely different from those associated with the presence of Z-DNA.

Animals↗
PubMed1984

Cerebral blood flow measurement as an indicator of the haemodynamic severity of carotid artery disease in man.

The non-invasive xenon-133 inhalation technique was used to measure regional cerebral blood flow in 61 patients with cerebrovascular disease in whom carotid angiography had been performed before carotid endarterectomy or extracranial/intracranial arterial bypass were considered. Hemispheric cerebral blood flow (CBF) was significantly lower in patients with an ipsilateral internal carotid artery occlusion than in those with a patent vessel. CBF values were also influenced by disease of the contralateral carotid artery. The cerebrovascular response to hypercapnia was a more sensitive index of carotid disease; a significant reduction in CO2 responsiveness was found both with occlusion and stenosis of the ipsilateral internal carotid artery. These data suggest that CBF measurements may be clinically useful in selecting patients for angiography and surgery.

Arterial Occlusive Diseases↗
PubMed1984

Synthesis and central nervous system properties of 2-[(alkoxycarbonyl)amino]-4(5)-phenyl-2-imidazolines.

A series of 2-[( alkoxycarbonyl )amino]-4(5)-phenyl-2-imidazolines was prepared and evaluated for central nervous system (CNS) effects (antidepressant, anticonvulsant, muscle relaxant, and depressant) in animal models. Some separation of those CNS activities was achieved through substitutions on the phenyl and imidazoline moieties. Halo-substituted phenyl compounds were among the most potent antidepressants in this series, while imidazole N-alkylation produced compounds with increased depressant effects (loss of righting reflex, mouse behavior). Comparison of in vitro and in vivo data for pairs of 2-[(methoxycarbonyl)amino]-4(5)-phenyl-2-imidazolines and their parent, 2-amino-4(5)-phenyl-2-imidazolines, suggests that the title compounds were prodrugs for the 2-amino-4(5)-phenyl-2-imidazolines in inhibition of norepinephrine reuptake.

Animals↗
PubMed1984

Predictability and coping with separation in infant squirrel monkeys.

Twelve infant squirrel monkeys were separated from their mothers once every 48 hr for a total of 20 separations. Half of the infants experienced separations for a fixed interval (FI) of 30 min. The remaining 6 infants experienced separations for a variable interval (VI) which averaged 30 min. During the separation periods, movement and vocalizations were recorded. Blood was sampled for later cortisol assay after the 1st, 5th, 10th, 15th, and final separation. The FI group showed increased levels of movement and vocalization over repeated separations when compared with the VI group. Cortisol showed significant increases over basal levels and remained elevated throughout the entire period in both groups. These findings suggest that predictability may be more stressful than unpredictability when organisms cannot control the predicted event.

Adaptation, Psychological↗
PubMed1984

Subselective preoperative embolization for meningiomas. A radiological and pathological assessment.

Over a 2-year period the authors have studied the effects of preoperative subselective embolization of meningiomas. Thirty-six consecutive patients shown by computerized tomography (CT) to have a meningioma underwent selective internal and external carotid artery angiography, and any significant external carotid artery feeders were embolized (27 cases). It was found that CT and dynamic radioisotope scan findings were unable to predict the degree of vascularity of the tumor or its suitability for embolization. Furthermore, these tests, repeated after embolization, were unreliable in detecting either the extent of necrosis or reduction in blood flow. The effects of embolization upon surgery were recorded, and the excised tumor specimen examined for evidence of thrombosis and infarction. Subselective embolization was determined to be a simple, safe, and effective method of producing tumor necrosis and intraoperative hemostasis in selected patients.

Adult↗
PubMed1984

Amiodarone-associated phospholipidosis and fibrosis of the liver. Light, immunohistochemical, and electron microscopic studies.

The hepatic morphological findings in 3 patients treated with amiodarone, a potent and effective antiarrhythmic drug, are reported. An enlarged liver and mild elevation of hepatic enzymes were the most important clinical findings. Fibrosis, cholangitis, mixed inflammatory infiltrate, and cytoplasmic granularity of the hepatocytes were the main histologic changes common to all cases. In 2 of the cases the presence of Mallory bodies was confirmed by electron microscopy. In 1 of these 2 cases, Mallory bodies were also confirmed by immunostaining. Ultrastructurally, numerous cytoplasmic inclusions with a membranous or lamellar structure identical to those described in phospholipidosis were the most striking features seen in hepatocytes, biliary epithelial cells, Kupffer cells, and endothelial cells.

Amiodarone↗
PubMed1983

Complications associated with preoperative radiation therapy and Iodine-125 brachytherapy for localized prostatic carcinoma.

Twenty-five consecutive patients with localized adenocarcinoma of the prostate treated with 1,050 rad preoperative radiation therapy and Iodine-125 seed brachytherapy arreviewed. Significant long-term postoperative complications included radiation cystitis (12%), radiation proctitis (4%), genital and leg edema (12%), stress incontinence (8%), total incontinence (4%), and impotence (26%). Complications occurred in 75 per cent of patients who received additional postoperative radiation. Improved staging with CT scan, lymphangiography, and Chiba needle biopsy of any possibly abnormal lymph nodes provided excellent preoperative staging with only 1 patient (6%) upstaged at surgery to Stage D1.

Adenocarcinoma↗
PubMed1983

Immediate and proactive effects of controllability and predictability on plasma cortisol responses to shocks in dogs.

Controllability and predictability are important modulators of the behavioral effects of aversive stimulation on animals. An experiment was conducted to further investigate both the immediate and proactive effects of controllability and predictability of shocks on adrenocortical responsivity. In an initial stress induction phase, the controllability and predictability of electric shocks were independently varied in groups of dogs, and plasma cortisol responses were measured. In a subsequent test phase, all groups of dogs received identical shocks in a novel situation. Cortisol responses to these test shocks were analyzed as a function of the controllability and predictability of previous induction shocks. The results showed that during stress induction, uncontrollable shocks produced significantly greater cortisol elevations that controllable shocks but that predictability had no significant effect on cortisol responses. However, unpredictable shocks during stress induction acted proactively to significantly increase cortisol response to novel test shocks, whereas prior controllability did not modulate subsequent responsivity to novel shocks.

Animals↗