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Biomedical subjects

M Girgis

Publications and source records attributed to M Girgis.

At least 19 recordsLinked to original sources
PubMed2004

Outcomes of adults with acute myelogenous leukemia in remission given 550 cGy of single-exposure total body irradiation, cyclophosphamide, and unrelated donor bone marrow transplants.

On the basis of observations from dog models and human studies, we hypothesized that a low-dose (550 cGy), single-exposure total body irradiation (TBI)-based regimen would result in improved survival when given to adult patients with acute myelogenous leukemia (AML) who were undergoing unrelated donor bone marrow transplantation in complete remission (CR). The regimen consisted of single exposure (550 cGy) of TBI given at a high dose rate (30 cGy/min) and cyclophosphamide. Graft-versus-host disease prophylaxis consisted of cyclosporine, methotrexate, and corticosteroids. Thirty-two consecutive adult patients (median age, 47 years) with AML in CR (15 in CR 1 and 17 in CR > or =2) were treated. Sixteen patients (50%) were alive and in remission at last follow-up (median, 2.2 years; range, 0.6-4.0 years). Kaplan-Meier estimates of overall and leukemia-free survival at 3 years were 55% +/- 14% (mean +/- SE) and 57% +/- 14% in CR 1 patients and were both 39% +/- 12% in CR > or =2 patients. Transplant-related mortality was 13% for patients in CR 1 and 41% for those in CR > or =2. Only 1 patient (3%) experienced fatal regimen-related organ toxicity, and only 1 had grade III or IV acute graft-versus-host disease. Graft failure was not observed. Relapse occurred in 22% of patients. This low-dose (550 cGy), single-exposure TBI-based regimen resulted in good survival and a low risk of fatal regimen-related organ toxicity in adult patients with AML who underwent unrelated donor bone marrow transplantation in CR.

Adult↗
PubMed1993

Bilharzial granuloma of the conus: case report.

Schistosomiasis of the central nervous system is uncommon. Schistosoma mansoni is the most common cause of a spinal cord lesion, although Schistosoma haematobium is sometimes responsible. The conus medullaris is the primary site for spinal lesion. The spinal lesion of schistosomiasis may be in the form of a mass lesion or acute necrotizing myelitis, or it may be silent and symptomless. Diagnosis of spinal cord schistosomiasis is commonly retrospective but may be suggested by laboratory and radiological studies. We were confronted with a case of bilharzial granuloma of the conus in a 7-year-old boy. This patient sought treatment for sphincteric disturbance. Myelography showed an intradural lesion in the area of the conus (opposite L1-L2). The mass proved pathologically to be S. haematobium granuloma. There was no previous history of bilharzial infestation. The neurological deficits improved markedly after surgery and antibilharzial treatment.

Child↗
PubMed1992

Evaluation of Klippel-Trenaunay syndrome with radionuclide total body angiography. A case report.

A 21-year-old Italian woman with extensive Klippel-Trenaunay syndrome (KTS) developed recurrent pulmonary embolism in spite of the insertion of a Greenfield filter in the inferior vena cava. Clinical and radiologic diagnostic tests failed to demonstrate the pathway of the emboli. Radionuclide venography and intravenous radionuclide total body arteriography were performed. These radionuclide procedures helped to evaluate the extent of KTS and to detect the route of the emboli. This is the first case of KTS studied with intravenous total body arteriography reported in the literature.

Adult↗
PubMed1989

The interface between bone, soft tissue, and dental implants.

The normal healing responses of soft tissues and bone to injury, including the sequence of cellular activity, are presented. The nature of the attachment of the implant to the biological tissues may be either poorly differentiated fibrous tissue or direct anchorage in vital bone (preferred). Attachment by a highly differentiated periodontal ligament is presently not possible. The gingival seal has been found to be similar to that around the natural tooth. Commercially pure titanium is one of the best materials to use in terms of its biological compatibility with bone; polymers, carbons and controlled surface, i.e. active bioglasses, are also satisfactory. A porous low modulus coating is useful. Design of the implant and force transfer, as well as surgical treatment are among the important factors that determine how the interface will develop.

Alveolar Process↗
PubMed1983

A combined histochemical-neurophysiological technique for investigating the extent of diffusion of intracerebrally injected drugs.

In order to 'dissect out' the function of a given region of the brain, the local application of a chemical transmitter probably parallels closely what is actually occurring biologically at the local site. This paper addresses itself to the problem of diffusion of drugs and describes the application of a modern device (the osmotic minipump) which produces a constant flow of minute quantities of the agent into the brain structure. Neurophysiological, behavioural, and histochemical investigations have been carried out in different species. Although the histochemical results of the minipump experiments indicate some spread, yet this seems to be at a concentration which would have no apparent pharmacological action. This was confirmed by our neurophysiological and behavioural studies and also by some recent reports in the literature.

Acetylcholinesterase↗
PubMed1981

Neuronal hypersensitivity to acetylcholinesterase inhibitors induced by a kindling stimulus in the rabbit brain.

Kindling has been studied primarily with electrical stimuli applied to subcortical structures in the limbic system. Several recent pharmacological studies have implicated muscarinic cholinergic synapses in the genesis of limbic epilepsy. The present investigation was designed to test the hypothesis that cholinergic neurons may constitute a critical element in the neuronal circuitry of kindling. Chemitrodes implanted in rabbit brains enabled both electrical and chemical stimulations of limbic structures. The results indicate that only few electrical kindling-stimuli produce prolonged hypersensitivity to intracerebrally injected physostigmine. A subsequent electrical stimulus continues the kindling progression. The cholinergic supersensitivity persisted for a long time and was suppressed only by intramuscular injections of scopolamine.

Acetylcholinesterase↗
PubMed1981

Electrical versus cholinergic kindling.

The present investigation was designed to test the hypothesis that cholinergic neurones may constitute a critical element in the neuronal circuitory of kindling. Chemitrodes implanted in monkey and rabbit brain enabled both electrical and chemical stimulations of limbic structures. The results indicated that only few electrical kindling stimuli produce prolonged supersensitivity to intracerebrally injected physostigmine. A subsequent electrical stimulus continues the kindling progression. The cholinergic supersensitivity persists for a long time and is only suppressed by intramuscular injections of scopolamine. These findings fit best with the hypothesis that participation of muscarinic cholinergic receptors may be an important requirement of the kindling process. It appears likely that similar types of mechanisms are involved both in chemical and electrical kindling.

Amygdala↗
PubMed1981

Combined use of the chemitrode with osmotic minipumps for experimental brain research.

This paper describes a simple-to-build minipump-chemitrode assembly which can be used for long term electrophysiological, chemical and behavioural studies. This system consists of an osmotic minipump, a cannula and an array of nine electrodes which are connected to a miniature Winchester Socket. A detailed plan for construction of both the chemitrode and the minipump-chemitrode is given together with some suggestions for possible usages in brain research(such as kindling). The osmotic minipump consists of a collapsible reservoir of flexible, impermeable material, surrounded by a sealed layer containing an osmotic agent--all of which is contained by a semipermeable membrane. Imbibed water generates hydrostatic pressure on the flexible lining of the reservoir, gradually compressing it, producing a constant flow of its contents through the delivery portal.

Animals↗
PubMed1981

Lesions made in the rabbit brain to assist the design and use of electrodes for amygdalotomy in man.

The lesion sizes produced by passing anodic currents of up to 10 mA through gold electrodes implanted in rabbit brains have been estimated histologically. The information has been used to design sheaves of similar electrodes implanted in human brains for amygdalotomy. The maximum current that can be passed through an electrode without generating an excessive temperature has been defined approximately.

Amygdala↗
PubMed1980

Acetylcholinesterase enzyme localization in the amygdala: a comparative histochemical and ultrastructural study.

The distribution of acetylcholinesterase enzyme was studied in the amygdala of some rodents, subprimates and several primates. The cytoarchitecture of the amygdala has presented various problems to anatomists, including the question as to how many nuclear groups and subgroups should be identified. Among the mammals examined, the arrangement of the amygdaloid nuclei is remarkably uniform and no clear phylogenetic trend can be recognised. Although there are minor differences, there seems to be a general similarity between most mammals examined in so far as the distribution of cholinesterase is concerned. The staining is less intense in the brains of the monkeys examined. The sole exception to the rule, that cholinesterase distribution is slightly different from nucleus to nucleus in different animals, is the magnocellular part of the basal nucleus. This amygdaloid nucleus stains quite strongly in all animals examined. From these findings, and those of others studying the distribution of choline acetyltransferase, it was concluded that the basal amygdaloid nucleus is cholinergic and possible cholinoceptive. The ultrastructural investigations appear to confirm this point. This is particularly applicable to the magnocellular part of the basal amygdaloid nucleus.

Acetylcholinesterase↗
PubMed1980

Distribution of acetylcholinesterase in the limbic system of the brain of the rabbit.

The aim of the study is to present a detailed and thorough description of the acetylcholinesterase enzyme (AChE) content of the limbic structures of the rabbit, now commonly used in our laboratory for investigating the electrographic-behavioral correlations of the cholinergic limbic system. We use 'chemitrodes' for intracerebral mi croinjections of cholinomimetic drugs; a detailed histochemical study (using Koelle's method) of the distributions of AChE enzyme in the limbic system of the rabbit was deemed necessary. Such areas as the septum and the amygdala are particularly poorly described in the rabbit and an attempt was made to clarify the confusion that still exists in the literature on the comparative anatomy and exact localization of these structures. On the whole, it could be inferred from this study that AChE-bearing neurons are generally better developed in phylogenetically older parts of the brain. Practically all the relays in Papez's 'cortical circuits of emotion' have a fairly AChE activity. As noted by us in other phyogenetically lower macrosmatic mammals, the reaction of AChE in the rabbit brain is more intense than in primates.

Acetylcholinesterase↗
PubMed1980

Psychotic depression: the common therapeutic principle.

Cholinergic prevalence together with a monaminergic deficit characterize the neurotransmitter imbalance underlying psychotic depression. Correction of this neurotransmitter imbalance is the principal purpose and goal of all treatment methods for the relief of psychotic depression. This can be accomplished by reducing the acetylcholine predominance or increasing the level of monaminergic functioning, or a combination of both approaches. The antidepressant tricyclic drugs combine a central anticholinergic action with an aminergic potentiating function. Electroconvulsive therapy is effective through activation of both cholinergic and aminergic systems, with removal of excess acetylcholine into the cerebrospinal fluid. Psychiatric surgery restores neurotransmitter balance by blocking excessive acetylcholine synthesis and activity.

Acetylcholine↗
PubMed1978

Neostigmine activated epileptiform discharge in the amygdala: electrographic-behavioral correlations.

This investigation was carried out to test the hypothesis that amygdaloid epileptiform activity is due to cholinergic hyperactivity. It was designed to study the underlying physiopathology of, and to act as an experimental model for, psychomotor epilepsy. Neostigmine was injected intracerebrally into the amygdala of the cebus monkey with chronically implanted "chemitrodes" fitted with EEG recording electrodes. The injections were made in the basal amygdaloid nucleus which normally shows very high acetylcholinesterase (AChE) enzymatic activity in histochemical preparations. Neostigmine injection resulted in very high amplitude spike activity in the amygdala only. Other brain areas, including the neighboring temporal cortex, did not show any marked EEG changes. In the first day or two, these EEG changes were associated with myoclonus localized in the ipsilateral muscles of facial expression and also associated with masticatory seizures. Subsequently the animal became aggressive and remained so several months after the injection of neostigmine. The EEG changes continued for approximately 6 weeks. Intramuscular injections of atropine diminished the amplitude of the epileptiform EEG discharges and modified slightly the animal's behavior.

Aggression↗
PubMed1977

Social implications of the "dyscontrol syndrome" (neuropsychiatric correlates).

The recent literature contains numerous publications which have tried to stimulate a new and biologically oriented approach to the problem of violence. Experimental brain research indicates that biologically important predatory and aggression responses have multiple representations in the nervous system. However, knowledge gained so far concerning emotional brain function in violent persons with brain disease, or from experimental research, can only infrequently be applied to combat the violence-triggering mechanisms in the brains of the non-diseased. In the hope of determining the neurological basis of aggression, the present author studied the brains of forty-two patients whose clinical history indicated definite aggressive behaviour. Results are reported and discussed. It is also the aim of this paper to discuss the social implications of the surgical treatment of patients with a "dyscontrol syndrome" whose investigations do not reveal definite evidence of "hard" signs and symptoms of brain pathology.

Aggression↗