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Biomedical subjects

M Hogan

Publications and source records attributed to M Hogan.

At least 55 records · Page 3Linked to original sources
PubMed1994

Circulating fibrocytes define a new leukocyte subpopulation that mediates tissue repair.

BACKGROUND: The host response to tissue injury requires a complex interplay of diverse cellular, humoral, and connective tissue elements. Fibroblasts participate in this process by proliferating within injured sites and contributing to scar formation and the longterm remodeling of damaged tissue. Fibroblasts present in areas of tissue injury generally have been regarded to arise by recruitment from surrounding connective tissue; however this may not be the only source of these cells. MATERIALS AND METHODS: Long-term culture of adherent, human, and murine leukocyte subpopulations was combined with a variety of immunofluorescence and functional analyses to identify a blood-borne cell type with fibroblast-like properties. RESULTS: We describe for the first time a population of circulating cells with fibroblast properties that specifically enter sites of tissue injury. This novel cell type, termed a "fibrocyte," was characterized by its distinctive phenotype (collagen+/vimentin+/CD34+), by its rapid entry from blood into subcutaneously implanted wound chambers, and by its presence in connective tissue scars. CONCLUSIONS: Blood-borne fibrocytes contribute to scar formation and may play an important role both in normal wound repair and in pathological fibrotic responses.

Animals↗
PubMed1993

Volumetric analysis of small bowel displacement from radiation portals with the use of a pelvic tissue expander.

PURPOSE: Many techniques and devices have been used in an attempt to minimize gastrointestinal morbidity of pelvic irradiation. The value of a temporary intrapelvic tissue expander to displace small bowel from pelvic radiotherapy fields was analyzed by comparing volumetric treatment parameters of patients with and without such a device. METHODS AND MATERIALS: Between 1983 and 1991, 77 patients with a diagnosis of endometrial (n = 35), colorectal (n = 41), or anal carcinoma (n = 1) received adjuvant postoperative radiotherapy after undergoing treatment planning simulation with the use of small bowel oral contrast medium. Fourteen of these patients underwent surgical placement of a temporary intrapelvic tissue expander prior to radiotherapy, and 63 patients did not. Small bowel volume within the treatment portals was measured for both initial pelvic and conedown fields for all cases, and compared between the two patient groups. RESULTS: The volume of small bowel within the initial pelvic fields receiving full dose irradiation was significantly less among patients with a tissue expander. For patients with a tissue expander, mean volume receiving full dose irradiation was 25 cm3 (median 0 cm3, range 0-297 cm3), whereas the corresponding volume was 239 cm3 (median 181 cm3, range 0-943 cm3) without a tissue expander (p < .0001). A similar reduction of irradiated small bowel volume was noted in the conedown fields with the use of a tissue expander (p = .07). Volumes receiving less than full dose irradiation were also less within the initial pelvic (p = .0001) and conedown (p = .002) fields with a tissue expander. Multivariate analysis of patient and treatment-related parameters showed the use of a tissue expander to be the only factor correlated with decreased small bowel volume within the treatment field (p = .003). Morbidity related to placement and removal of the tissue expander was acceptable. Acute radiation-related morbidity was significantly less in patients irradiated with a tissue expander in place (p < .001). CONCLUSIONS: Placement of an intrapelvic tissue expander was correlated with decreased small bowel volume within the radiotherapy treatment field. Diminished radiation-induced acute gastrointestinal morbidity was noted with use of a tissue expander.

Aged↗
PubMed1993

Intraperitoneal cisplatin and etoposide in peritoneal mesothelioma: favorable outcome with a multimodality approach.

Ten patients with histologically documented peritoneal mesothelioma were treated with intraperitoneal cisplatin 200 mg/m2, sodium thiosulfate rescue and etoposide 65-290 mg/m2 every 4 weeks for a maximum of six cycles. All had epithelial or mixed epithelial-fibrous histology. Toxicity was tolerable, with 50% sustaining grade 3 or 4 granulocytopenia. There was one episode of neutropenic fever. Grade 2 peripheral neuropathy occurred in one patient, grade 1 in five patients. Complete remission occurred in one of five patients with measurable disease. Median survival for patients whose tumors were surgically debulked to < 2 cm residua prior to treatment was 22 months, while it was 5 months for those with measurable, surgically inaccessible disease (P = 0.0731 by Cox regression proportional hazard model). These data suggest that patients who present with resectable disease may benefit from an aggressive adjuvant approach. This possibility warrants prospective testing in a randomized clinical trial.

Adult↗
PubMed1993

Regulation of phosphatidylcholine synthesis in fetal type II cells by CTP:phosphocholine cytidylyltransferase.

Phosphatidylcholine synthesis increases in fetal rat type II cells during late gestation, as demonstrated by an increased incorporation of radiolabeled palmitate, glycerol, acetate, and choline into phosphatidylcholine. However, the percentage of phosphatidylcholine present in the saturated form remains essentially constant. The developmental profile of the enzymes of the CDP-choline pathway suggests that CTP:choline-phosphate cytidylyltransferase catalyses a rate regulatory step in de novo phosphatidylcholine synthesis by fetal type II cells. When cytidylyltransferase activity is assayed in different subcellular fractions, the greatest increase, as a function of development, is found in microsomes. This developmental increase is accompanied by a shift in subcellular distribution of cytidylyltransferase activity from cytosol to microsomes in fetal type II cells during late gestation. This shift is evident even when cytidylyltransferase activity is assayed in the presence of 0.5 mM phosphatidylcholine/oleic acid (1/1 molar ratio) vesicles. We speculate that either a subcellular translocation of CTP:phosphocholine cytidylyltransferase from cytosol to microsomes or an increase in cytidylyltransferase gene expression are responsible for the developmental increase of de novo phosphatidylcholine synthesis by fetal type II cells.

Animals↗
PubMed1992

Advanced glycosylation endproducts block the antiproliferative effect of nitric oxide. Role in the vascular and renal complications of diabetes mellitus.

Advanced glycosylation endproducts (AGEs) accumulate on long-lived tissue proteins such as basement membrane collagen and have been implicated in many of the long-term complications of diabetes mellitus. These products originate from glucose-derived Schiff base and Amadori products but undergo a series of complex rearrangement reactions to form ultimately protein-bound, fluorescent heterocycles. AGEs can react with and chemically inactivate nitric oxide (NO), a potent endothelial cell-derived vasodilator and antiproliferative factor. Since mesenchymal cell proliferation is an early and characteristic lesion of diabetic vasculopathy and glomerulopathy, we investigated the possibility that collagen-bound AGEs functionally inactivate the antiproliferative effect of NO. In model cell culture systems, AGEs were found to block the cytostatic effect of NO on aortic smooth muscle and renal mesangial cells. The inactivation of endothelial cell-derived NO by basement membrane AGEs may represent a common pathway in the development of the accelerated vascular and renal disease that accompany long-term diabetes mellitus.

Animals↗
PubMed1991

Phase I pharmacokinetic study of intraperitoneal etoposide.

The synergistic interaction of etoposide with cisplatin in certain tumors prompted an evaluation of its potential role in the i.p. treatment of ovarian cancer and other intraabdominal malignancies. We conducted a Phase I evaluation of etoposide as a single agent to determine the maximum tolerated dose i.p., to describe dose-limiting and other toxic effects, and to examine the pharmacokinetics of etoposide in this setting. Etoposide was diluted in 2 liters of normal saline, and instilled i.p. over 10 to 25 min following maximal drainage of ascites. The dwelling time was 4 h, followed by peritoneal drainage. Twenty-two patients received 56 courses at doses which ranged from 100 to 800 mg/m2. The median age was 49, the median performance status was 1, and 18 patients had received prior chemotherapy, with or without radiation. The principal acute toxicity was abdominal pain in 10 patients; this was usually accompanied by signs of peritoneal irritation and was always responsive to nonsteroidal antiinflammatory medications. The major toxicity was dose-related neutropenia; Grade 3 or 4 toxicity affected five of six patients at 800 mg/m2. Thrombocytopenia, nausea and vomiting, and alopecia were also observed. The recommended dose for further study is 700 mg/m2. The pharmacokinetics of etoposide in plasma and peritoneal fluid was measured in 19 patients. Peritoneal levels over the 4-h dwelling time declined monoexponentially with a harmonic mean half-life of 3.5 h (range, 1.9 to 7.8). Plasma levels rose to a peak at 2.9 +/- 1.7 (SD) h and then declined exponentially with a harmonic mean terminal half-life of 7.7 h (range, 4.2 to 15.6). The plasma area under the concentration-time curve increased linearly with respect to dose. The relative pharmacological advantage (ratio of peritoneal to plasma area under concentration-time curve) for i.p. administration was measured as 2.8 and was independent of dose. Based on the high plasma protein binding of etoposide (94%) and the minimal protein binding in the fluid instilled i.p., the ratio of the areas under the concentration-time curves of free drug is estimated to be 4%. These results illustrate that tumor confined to the peritoneal cavity would be exposed to substantially higher free (diffusible) drug concentrations following i.p. than following i.v. administration and support the further evaluation of etoposide by this route.

Adult↗
PubMed1991

Pharmacologic study of etoposide and cisplatin by the intraperitoneal route.

Based on the previous demonstration of a high peritoneal-to-plasma ratio of drug exposure for intraperitoneal (IP) etoposide, the authors performed a clinical/pharmacokinetic trial of etoposide (600 mg/m2) in combination with cisplatin (100 mg/m2). The drugs were administered concurrently IP, and allowed to dwell for 4 hours, after which the peritoneum was drained. Six patients received 13 cycles of treatment. Grade 4 neutropenia occurred in three patients; toxicity was otherwise moderate. Plasma etoposide concentrations reached a peak at 4.2 +/- 2.5 hours and declined exponentially with a terminal half-life of 9.5 +/- 3.6 hours. Peritoneal etoposide concentrations declined monoexponentially with a half-life of 3.7 +/- 2.6 hour. The calculated peritoneal-to-plasma ratio of unbound etoposide was 35. The plasma and peritoneal half-lives of ultrafilterable cisplatin were 21.7 +/- 14.1 hours and 1.8 +/- 0.7 hours, respectively. The peritoneal/plasma area under curve AUC ratio was 18.3. These pharmacokinetic indices for both drugs are consistent with those obtained with the use of each drug as a single agent. Thus, the concomitant use of one does not alter the pharmacokinetic activity of the other. The high AUC ratios support the further clinical development of these drugs in combination in the intraperitoneal setting.

Adenocarcinoma↗
PubMed1991

The effects of a competitive NMDA receptor antagonist (CGS-19755) on cerebral blood flow and pH in focal ischemia.

We report the effects of intravenous infusion of CGS-19755, a potent competitive N-methyl-D-aspartate (NMDA) antagonist, on local cerebral pH (LCpH) and local CBF (LCBF) in rats with occluded left middle cerebral and common carotid arteries. LCpH and LCBF were determined simultaneously by a double-label autoradiographic technique 4 h after vascular occlusion in three groups: no treatment, carrier infused, and a group receiving CGS-19755 at 10 mg/kg bolus immediately after occlusion followed by infusion at 5 mg kg-1 h-1 for 4 h. Compared with rats receiving carrier, several cortical structures on the side of occlusions showed significantly higher CBF in rats receiving CGS-19755. This drug also corrected the pH in several left cortical structures to values significantly higher than in the rats receiving carrier. The correction in LCpH was not limited to those regions showing significant elevations in LCBF. In the nonoccluded hemisphere, CGS-19755 significantly increased the hemispheric mean blood flow from 122 +/- 17 to 221 +/- 64 ml 100 g-1 min-1 (mean +/- SD of all structures, p less than 0.01) without any changes in LCpH. Cortical but not basal ganglia infarct volume was significantly smaller in rats receiving CGS-19755 than in the carrier-treated group. These results suggest that, at least partially, the neuroprotective effect of CGS-19755 in ischemia may be related to changes in CBF and pH in addition to its antagonist effect on the NMDA receptor.

Animals↗
PubMed1991

Activity of the dihydropyridine calcium channels following cerebral ischemia.

With an in-vivo autoradiographic method the binding of 3H-nimodipine (CAS 66085-59-4) and cerebral blood flow (14C-iodoantipyrine method) were measured in rat brain after occlusion of the middle cerebral and common carotid arteries. The dependence of the binding to neuronal cellular membranes on the duration of ischemia can be interpreted as indicator of the tissue's functional state or its responsiveness to therapy with calcium entry blockers. In the two analyzed structures, dorsolateral caudate and overlying sensorimotor cortex, the appearance of infarction is preceded by an activation of the nimodipine binding sites followed by persistent decline of the binding intensity. Binding to nimodipine may therefore be a useful marker of ischemic but salvageable brain tissue.

Animals↗
PubMed1991

Promoting bicycle helmets: a new focus for injury prevention.

Bicycle accidents cause many serious injuries and deaths in the United States, often as a result of head injury in riders not wearing helmets. Helmets reduce the incidence of head injury, and an aggressive safety education campaign has been shown to increase the number of children wearing helmets while riding. Such a campaign has been initiated in the Central Indiana area. The campaign is designed to educate families and to promote bicycle helmet use among children and their parents. Suggestions are given on how physicians can help educate, distribute information and encourage bicycle helmet use through their contact with families. A resource list is included so these materials can be easily obtained. Ultimately, we hope such a program will increase helmet use and consequently reduce morbidity and mortality from head injury in Indiana's children.

Bicycling↗
PubMed1990

Transportation of newborn infants.

The benefit of an organized neonatal transport system is well established. Over a 30 month period, January 1987 to June 1989, 172 babies were transported to the Dublin maternity hospitals. Birth weights ranged from 640 to 5,180g 106 (62%) were less than 37 weeks gestation. Indications for transport included respiratory distress syndrome (54), prematurity only (43), convulsions and/or neurologic dysfunction (23), jaundice (11) and apnoea (11). One hundred and sixty-eight were transferred by ambulance and four by helicopter. Twenty travelled more than 100 miles. Forty (23%) received assisted ventilation during transport. On arrival 37 (21%) had temperature less than 36 degrees C; 22 (13%) had blood sugar less than 2.2 m mol/l and 34 (20%) had arterial ph less than 7.25. Fifty per cent of referral letters had incomplete information. Treatment and care given en route was recorded in only 28 babies. Twenty-four babies (14%) died. Infants who died were more likely to have been of low birth weight, travelled a long distance, been hypothermic, had poor arterial gases, had blood sugars less than 2.2 m mol/l, and had poor referral letters. This review indicates that death and morbidity continue to be associated with the present system of postnatal transfer of newborn infants. The urgent need for an organized neonatal transport service remains unmet.

Emergency Medical Services↗
PubMed1990

Nimodipine binding in focal cerebral ischemia.

We investigated the binding properties of the voltage-sensitive calcium channel antagonist nimodipine in a rat model of focal cerebral ischemia. Male Sprague-Dawley rats weighing 250 g underwent occlusion of both the proximal middle cerebral artery and the ipsilateral common carotid artery. 3H-nimodipine (130 Ci/mmol) was infused intravenously and circulated for 30 minutes before the rats were killed at 5 minutes, 4, 24, and 48 hours after occlusion. The brains were removed and examined by autoradiography. We observed a focal increase of nimodipine binding in severely ischemic regions at 5 minutes after occlusion, which also appeared in regions with presumed penumbral blood flow levels at 4 hours after occlusion. We hypothesize that nimodipine binds to activated calcium channels in ischemic tissue. This increased binding depends on the duration and severity of cerebral ischemia. Sequential measurements of nimodipine binding may allow the identification of regions with potentially reversible effects of ischemia and the monitoring of their response to therapy.

Animals↗
PubMed1990

Computer assisted insulin dosage adjustment--perspectives for diabetes control.

Pocket computers provide the physician's (expert's) advice at home and by that may increase the number of self-adapting diabetics and alleviate documentation and evaluation of therapy data. By a more complex quantitative approach metabolic control may be improved beyond the range which is attained by optimal intensified education, as clinical trials showed. By their reproducible measures a learning process seems to be induced in the patients. Risks like hyperinsulinisation may be overcome by watch dog functions and suitable algorithms. In addition to these patient-oriented functions the automatic data acquisition may be used for secondary PC-assisted data interpretation and more complex advice at the physicians office. For compliance reasons the system concept has to be user-friendly considering size, easy handling and compensating for the loss of a written log book by adequate display.

Algorithms↗
PubMed1989

[Type 2b multiple endocrine adenomatosis].

The case report presented here demonstrates the typical diagnostic and therapeutic problems in a young patient with a multiple endocrine adenomatosis type 2b. The patient exhibited the complete syndrome with its endocrine and non-endocrine organ manifestations (medullary thyroid cancer, bilateral pheochromocytoma, mucosal neuromas, marfanoid habitus, pes equinus, diverticulosis). First presenting symptom was a diverticulitis that led to an emergency surgical intervention because of perforation of the sigmoid colon. Perioperatively, blood pressure increases were noted that were then followed by further diagnostic measures leading to adrenalectomy, thyroidectomy and surgery for local metastases of the thyroid cancer. Family screening demonstrates so far a possible sporadic form of the disease.

Adrenal Gland Neoplasms↗
PubMed1988

The in vitro insertion of monoamine oxidase B into mitochondrial outer membranes.

Bovine monoamine oxidase (MAO) B has been synthesized in vitro using a reticulocyte lysate translation system directed by bovine liver poly(A)+ RNA. The newly synthesized enzyme apparently lacks a cleavable N-terminal extension, but MAO B is readily incorporated into mitochondria or isolated mitochondrial outer membranes prepared from rat liver. ATP is not required for the binding of the newly synthesized enzyme to the outer membranes, but is necessary for the insertion of MAO B into these membrane vesicles. The ATP is not required to generate a mitochondrial membrane potential as assembly occurs under conditions that preclude either the formation or the maintenance of the potential. MAO B will bind to but not become incorporated into outer membrane vesicles which have been treated with trypsin, suggesting that the insertion of MAO B also depends on protein factors present on the outer membranes.

Animals↗