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Biomedical subjects

L Ogden

Publications and source records attributed to L Ogden.

At least 19 recordsLinked to original sources
PubMed2004

Measurement of abdominal fat by CT compared to waist circumference and BMI in explaining the presence of coronary calcium.

OBJECTIVE: To evaluate the association between standard and computed tomography (CT)-based measures of obesity and subclinical atherosclerosis, defined as coronary artery calcium (CAC) by Electron Beam Computed Tomography (EBCT). DESIGN: Cross-sectional, observational study of anthropometric and CT obesity measures and presence of CAC. SUBJECTS: Participants were 383 men and 379 women, aged 20-58 y and asymptomatic for coronary artery disease (CAD). MEASUREMENTS: Intra-abdominal fat (IAF) and subcutaneous fat (SQF) were measured at the level of lumbar 2-3 and 4-5 spaces, using EBCT. Body mass index (BMI) was calculated from height and weight, and minimum waist circumference and maximum hip circumference were measured. CAC was measured by EBCT. RESULTS: In both men and women, BMI, waist circumference, IAF, and SQF were significantly related to CAC. However, BMI or waist circumference explained variation in the presence of CAC as well as IAF or SQF, univariately and after adjustment for additional cardiovascular risk factors. CONCLUSION: CT-based obesity exposure measures are not superior to BMI or waist circumference in association studies of subclinical CAD.

Abdominal Wall↗
PubMed1999

Blood flow in a chronic entrapment neuropathy model in the rabbit sciatic nerve.

A model of chronic entrapment neuropathy in the rabbit sciatic nerve was developed to try to elucidate the pathogenesis of chronic nerve entrapment. A non-compressive Silastic cuff was wrapped around the nerve at the mid-thigh level in eight rabbits. A sham operation that only elevated the sciatic nerve was performed in seven control rabbits. Six months later, the blood flow in the cuffed and the control sciatic nerves was determined with intra-arterially injected microspheres. Blood flow was significantly reduced in the entrapped nerve, compared to control nerves, but only in the segment proximal to the cuff. After surgical release of the cuff, the blood flow significantly increased in the proximal segment. This suggested that decreased blood flow may occur, but not necessarily at the site of nerve entrapment. Nerve conduction velocity changes were also consistent with an entrapment neuropathy. However, there were no significant quantitative morphometric changes at the nerve entrapment site, that is, in myelin thickness/nerve diameter ratio, distribution of axon sizes, and mean nerve fiber diameter. This indicates that only a mild entrapment was created.

Animals↗
PubMed1996

Ischemia increases the angiogenic potency of basic fibroblast growth factor (FGF-2).

The aim of this study was to investigate the angiogenic response to exogenously administered basic fibroblast growth factor (FGF-2) in normal and ischemic skin, using the hairless mouse ear microcirculatory model. The hairless mouse ear is a well-established model for in vivo studies of skin microcirculation. Using this model, angiogenesis- and angiogenesis-associated changes in the microcirculation can be directly and continuously viewed and quantified in a variety of different experimental settings. To create ischemia in the mouse ear, all but one of the three to four feeding vessels nourishing the ear were ligated 3 days prior to a local subdermal injection of FGF-2 (9.3 + 1-0.5 mm/mm2) or saline into the dorsum of the ears. Angiogenesis was quantified by direct observation, at high magnification, of the injection site where increases in total vessel length (TVL) were measured repeatedly over 18 days following injection. We found a significant (P < 0.01) increase in TVL in normal and ischemic ears injected with FGF-2. Saline injection also induced a significant increase in TVL in ischemic ears. However, the angiogenic response to FGF-2 in ischemic ears was significantly stronger than saline alone in ischemic ears or saline or FGF-2 in normal ears. This response could be used clinically to accelerate angiogenesis and thus increase perfusion in ischemic tissue.

Animals↗
PubMed1994

Partial purification, tissue distribution and modulatory activity of a crustacean cholecystokinin-like peptide.

Reversed-phase chromatography was used to separate several forms of cholecystokinin-like peptides (CCKLP) from the pericardial organs (PCOs) of the spiny lobster Panulirus interruptus. Fast protein liquid chromatography of PCOs, stomatogastric ganglia (STGs) and eyestalks revealed five peaks of CCKLP (peaks A-E) that were common to all three tissues, as well as two additional peaks (peaks F and G) in the STG. Peaks A-E were present in the hemolymph of fed, but not starved, lobsters. The bioactivity of peaks A-E was tested on the gastric mill rhythm of the isolated STG. Only peak E elicited activity. The effects of peak E included activating the gastric mill rhythm in quiescent preparations and strengthening existing rhythms in a dose-dependent manner. Further purification of peak E by high performance liquid chromatography resolved this peak into two immunoreactive peaks, one of which retained its bioactivity. The effects of peak E were blocked by the CCK antagonist proglumide. These results are consistent with a role for peak E in the feeding-induced activation of the gastric mill.

Animals↗
PubMed1993

Blood flow and tissue survival in the rabbit venous flap.

The extent of venous flow, revascularization, local fluid imbibition, and metabolic status was evaluated in an experimental venous flap model. Thirty-six rabbits divided into six groups of six rabbits each had a 3.5 x 2.5 cm venous flap elevated along the thoracoepigastric vein, connected only by its proximal and distal vein, and sutured back. A composite graft of the same size was created on the contralateral side. Venous flaps survived 14 days, while composite grafts consistently did not. The vascular network was partially filled with fluorescein tracer within an hour after flap creation, even with an underlying Silastic sheet. Filling improved over several days, consistent with rapid revascularization. Composite grafts showed no immediate filling and delayed revascularization. Venous flow was apparently insufficient to enhance metabolism, since both glucose and lactate levels were equivalent between venous flaps and composite grafts. This supports the concept that an enhanced revascularization may be the primary mechanism of survival for venous flaps.

Animals↗
PubMed1991

Comparison of one- and two-stage nerve grafting of the rabbit median nerve.

The hypothesis that improved axonal regeneration occurs through nerve grafts when scarred tissue is removed and distal coaptation completed during a delayed, secondary operation was tested in a rabbit model. The ulnar nerve was used as a donor nerve graft to a final three-centimeter deficit of the contralateral median nerve. This was done either in one stage or in two stages, with resection of scar and coaptation at the distal site done ten weeks later. Evaluation included nerve conduction velocity, compound action potential area, muscle contraction force, muscle weight, and axon counts. Two-stage nerve grafts at 24 weeks were significantly inferior to one-stage grafts only in compound action potential area. Both nerve grafts showed significant improvement in function from twenty-four to sixty-two weeks as measured by nerve conduction velocity; two-staged grafts in addition showed a significant increase in compound action potential area and twitch contraction force. The data are inconclusive regarding the absolute superiority of two-stage versus one-stage grafting. Different timing for the second stage may be required.

Action Potentials↗
PubMed1991

Sensory and motor fiber differentiation with Karnovsky staining.

We examined four acetylthiocholine methods based on Karnovsky's procedure--two fast-acting requiring 1 hour and two slow-acting requiring 24 hours. We compared these with our modification, which requires less than an hour and is simple to use. Rabbit sciatic nerves and spinal cords were used to compare methods. Our modification showed clearer differentiation than other fast-acting methods and staining identical to slow-acting methods. In blind examination of radial nerve specimens stained with our method, motor and sensory fascicles were correctly identified, showing sensitivity and specificity of 100%. In 12 clinical cases, our method produced staining in the proximal stump as long as 16 months after injury and in the distal stump as long as 5 days after injury. In 10 of 12 patients, this staining helped in aligning motor fascicles to motor fascicles and sensory fascicles to sensory fascicles.

Acetylthiocholine↗
PubMed1989

Experimental replantation of canine forelimbs after 78.5 hours of anoxia.

To assess the effect of ischemia on osteocyte survival and longitudinal growth in bone, one forelimb of eight puppies and seven dogs was amputated, perfused with iced Collins solution, maintained at 4 degrees C for 72 hours (78.5 hours total anoxia), and replanted. Five puppies were kept for 1 year to assess bone growth. Undergoing bone labeling on days 1, 8, and 15, the other animals were sacrificed at 22 days to assess osteocyte survival. Osteocytes survived replantation in all dogs and one puppy; most osteocytes died in two puppies. In five long-term puppies, central epiphyseal growth was disturbed, but the peripheral portions maintained nearly normal growth, with almost normal bone length being achieved at 1 year.

Animals↗
PubMed1987

The ability of oxygenated fluorocarbon solution to minimize ischemic skeletal muscle injury.

The amputated canine limb was used to create a devascularized skeletal-muscle-containing model. The extremity was perfused with one of several solutions or merely cooled as a preservative measure during the devascularized period and then replanted. Perfusion of the limb with oxygenated fluorocarbon solution minimized edema formation and leakage of skeletal muscle enzymes into the serum following revascularization as compared to the other perfusates or to mere cooling. Histopathologic changes within the revascularized muscle were also minimized by the oxygenated fluorocarbon perfusion. It is probable that these findings will correlate with improved function of replanted extremities or free muscle flaps. The applicability of these findings to human extremity replantation and free-flap transfer is postulated. However, long-term human studies will be necessary to assess the function of extremities and flaps perfused with this solution prior to its general use in extremity replantation and free-flap transfer.

Animals↗
PubMed1986

The role of the epiphyseal and metaphyseal circulations on longitudinal growth in the dog: an experimental study.

An experimental model using the immature canine proximal fibular epiphysis was developed to isolate and investigate the effects of the epiphyseal and metaphyseal circulations on longitudinal growth. Experimental constructs studied the epiphyseal circulation, the epiphyseal and metaphyseal circulations, a devascularized growth plate, and a control group. Twenty-four limbs were studied by serial x-ray films and microangiographic and histologic analyses at time of death, 24 weeks after surgery. The data from this preliminary study show that both metaphyseal and epiphyseal circulations are necessary for predictable longitudinal growth.

Animals↗
PubMed1985

Subclassification of small cell cancer of the lung: the Southeastern Cancer Study Group experience.

Cancers in more than 300 patients being treated by Southeastern Cancer Study Group protocols for small cell carcinoma of the lung (SCCL) were subclassified as oat cell or intermediate types by criteria developed by two groups of investigators. With Cox survival and logistic regression models, no differences in survival or responsiveness to therapy were found between these types of tumors. These and previously published results suggest that the only intermediate tumors worth distinguishing are the "22/40" tumors with morphologic features precisely intermediate between those of SCCL and non-SCCL, including mildly vesicular nuclei, common small nucleoli, and rims of stained cytoplasm. Such tumors are the dividing point between SCCL and non-SCCL and constitute a small fraction of the spectrum from SCCL to non-SCCL.

Carcinoma, Small Cell↗
PubMed1984

Combination chemotherapy in small cell lung carcinoma. A randomized study of two intensive regimens.

From April, 1979 to November, 1981, 293 patients with small cell lung carcinoma (SCLC) were entered on a randomized, controlled study comparing the two induction regimens of high-dose CAV (HD-CAV) (cyclophosphamide [CTX] 1200 mg/m2, doxorubicin [ADR] 70 mg/m2 and vincristine [VCR] 1 mg/m2 intravenously (IV) on days 1 and 21) versus, conventional-dose CAV + VP-16 (etoposide) (CAV-VP) (CTX 1000 mg/m2, ADR 40 mg/m2, VCR 1 mg/m2 IV on days 1 and 21 with VP-16 100 mg/m2 on days 1-3, and 21-23). Responding and stable patients were continued on conventional-dose CAV for 5 consolidation courses. Prophylactic brain irradiation delivered after the first consolidation course in responders was optional. Patients were included in the study if they had extensive disease (i.e., beyond one hemithorax), no prior chemotherapy, or radiotherapy and performance status of 50 or above. After 2 induction courses, 215 cases are evaluable. Of these, 76 of 106 (72%) patients treated with HD-CAV have responded (greater than 50% regression), including 13 complete responders (CRs) versus 80 of 108 (74%) patients on CAV-VP, including 15 CRs. Of the 130 evaluable patients who have completed consolidation (HD-CAV, 65; CAV-VP, 65), an additional 22 patients achieved CR (HD-CAV, 12; CAV-VP, 10) for an overall CR rate of 24%. Median duration of remission was 33.6 weeks for HD-CAV and 35.6 weeks for CAV-VP (P = 0.61). Median duration of complete response for HD-CAV was 33.8 weeks and for CAV-VP 36.7 weeks (P = 0.81). Survival curves were similar for the two regimens, with medians of 42.1 weeks for HD-CAV and 42.3 weeks for CAV-VP (P = 0.35). Survival correlated with performance status and quality of response. As anticipated, the major toxicity for both induction regimens was leukopenia. During induction, granulocyte nadirs of less than 500/mm3 occurred in 81% of patients on HD-CAV and 77% of patients on CAV-VP. Thus, dose intensification appears to produce high response rates and modest complete response rates in extensive SCLC, but it does not appear to improve materially survival compared to prior reports of conventional-dose therapy.

Adult↗
PubMed1984

Separation of small-cell from non-small-cell lung cancer. The Southeastern Cancer Study Group pathologists' experience.

We reviewed the pathology materials from 691 patients with lung cancer who participated in therapy protocols with the Southeastern Cancer Study Group. We found good agreement (94%) between pathologists over the separation of small-cell carcinomas from non-small-cell carcinomas. Thus, oncologists and cooperative groups should rely on their local pathologists' diagnoses for the major choices of therapies in lung cancer and realize that there remain a small number of overlapping tumors that are not uniformly diagnosed by routine light microscopy and that require more sophisticated techniques if their diagnosis is to be accurate.

Carcinoma, Small Cell↗
PubMed1982

Experimental vascularized total joint autografts--a primate study.

Autogenous vascularized and nonvascularized total joint transfers were studied in the hands of Macaca fascicularis monkeys. Nine second toe proximal interphalangeal joints were transferred as a vascularized free graft to the hand, and the excised finger joints were transferred to the foot as a nonvascularized free graft. The grafts were examined clinically and histopathologically at 16 weeks to 10 months. Two of the nonvascularized free grafts were amputated because of infection and necrosis. Three had chronic infections. The four surviving nonvascularized grafts demonstrated necrosis of the hyaline cartilage and degenerative changes. Of the nine vascularized joints, one developed a wound infection that required amputation, another failed at 2 weeks because of wound dehiscence, and the remaining seven survived with preservation of the hyaline articular surfaces. The experimental technique was designed to be easily applied to clinical use. A skin island is provided as a "patency/viability monitor." The extensor mechanism is included in the graft for early function.

Animals↗