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Biomedical subjects

L G Newman

Publications and source records attributed to L G Newman.

7 recordsLinked to original sources
PubMed1995

Imaging techniques in the diabetic foot.

Osteomyelitis underlies the majority of diabetic foot ulcers, and it is usually not detected clinically. Leukocyte scanning with indium oxyquinoline has greater sensitivity than radiographs, bone scans, and MR imaging in diagnosing osteomyelitis in diabetic foot ulcers. All ulcers that expose bone, and perhaps moderately deep ulcers as well, should be treated for osteomyelitis because of the high prevalence of this infection (100% and 82%, respectively). Osteomyelitis should be evaluated for in shallow ulcers by radiographs, followed by leukocyte scans if the former tests are negative. Bone biopsies should be performed if possible because cultures may guide antibiotic treatment.

Amputation, Surgical↗
PubMed1992

Effects of amlodipine on myocardial infarction, infarct expansion, and ventricular geometry in the rat.

Infarct expansion remains an important sequela of myocardial infarction. Both angiotensin converting enzyme inhibitors and intravenous nitrates reduce early infarct expansion in humans. This is believed to be caused by the reduction in left ventricular systolic wall stress that results from the arteriolar vasodilatation they produce. Patients are frequently already receiving calcium channel blockers at the time of infarction or these drugs are sometimes administered in the perimyocardial infarction period. The calcium blockers of the dihydropyridine class might be expected to modify infarct expansion. However, their effect on this process has not been studied. We therefore evaluated the effect of early treatment with the calcium blocker amlodipine, a potent arteriolar vasodilator with minimal negative inotropic properties, on chronic myocardial infarction in the rat. Permanent left coronary occlusion was created after pretreatment with amlodipine, 0.25 mg/kg (low dose) or 1.0 mg/kg (high dose), or placebo, intravenously twice a day, and continued for 7 days after infarction. Hearts (n = 50) were perfusion fixed 21 days after infarction and analyzed for infarct extent, scar thickness, left ventricular shape and size, and expansion index. Both doses decreased mean blood pressure (119 +/- 3 to 99 +/- 5 mm Hg low dose, p = 0.004; 110 +/- 5 to 84 +/- 4 mm Hg high dose, p = 0.0003), with reflex tachycardia only after the high dose (heart rate 395 +/- 9 to 434 +/- 11, p = 0.001). Infarct extent was equal in the three groups (39 +/- 2%, 41 +/- 2%, and 41 +/- 3% of left ventricular circumference for control, low, and high doses, respectively). The three groups did not differ significantly with regard to left ventricular cavity cross-sectional area (80 +/- 4, 77 +/- 3, and 87 +/- 3 mm2, control, low, and high doses, respectively; p = 0.07 high dose vs control), mean scar thickness (0.74 +/- 0.06, 0.73 +/- 0.05, and 0.65 +/- 0.06 mm, control, low, and high doses, respectively; p = NS), and expansion index (1.52 +/- 0.10, 1.58 +/- 0.12, and 1.95 +/- 0.19, control, low, and high doses, respectively; p = 0.08 high dose vs control). In the subgroup with larger infarcts (infarct extent greater than 0.39 of left ventricle), the expansion index was higher in the high-dose group (2.37 +/- 0.23 vs 1.64 +/- 0.17 control; p = 0.04). In this model, treatment with amlodipine does not limit infarct extent or reduce early infarct expansion and left ventricular dilatation, even when initiated before infarction.(ABSTRACT TRUNCATED AT 400 WORDS)

Amlodipine↗
PubMed1992

Leukocyte scanning with 111In is superior to magnetic resonance imaging in diagnosis of clinically unsuspected osteomyelitis in diabetic foot ulcers.

OBJECTIVE: To compare the accuracies of MRI and leukocyte scanning in diagnosing clinically unsuspected osteomyelitis in diabetic foot ulcers. RESEARCH DESIGN AND METHODS: A prospective study of 16 diabetic foot ulcers in 12 patients, including both ambulatory and hospitalized patients, was performed at a university medical center. Pedal images were obtained by leukocyte scanning with [111In]oxyquinoline and MRI. Definitive diagnosis of osteomyelitis then was determined by bone biopsy for culture and histology. RESULTS: Biopsy-proven osteomyelitis was present in 7 (44%) of the 16 foot ulcers. The diagnosis was suspected clinically in 0%. Leukocyte scanning was 100% sensitive, whereas MRI was only 29% sensitive in diagnosing osteomyelitis in diabetic foot ulcers. Specificities were 67 and 78%, respectively. The positive and negative predictive values (70 and 100%, respectively) for the leukocyte scan also were greater than those of MRI (50 and 58%, respectively). CONCLUSIONS: Leukocyte scanning is superior to MRI in detecting clinically unsuspected osteomyelitis in diabetic foot ulcers.

Biopsy↗
PubMed1991

Unsuspected osteomyelitis in diabetic foot ulcers. Diagnosis and monitoring by leukocyte scanning with indium in 111 oxyquinoline.

OBJECTIVE: The prevalence of osteomyelitis in diabetic foot ulcers is unknown. Early diagnosis of this infection is critical, as prompt antibiotic treatment decreases the rate of amputation. We therefore assessed the prevalence of osteomyelitis in 35 diabetic patients with 41 foot ulcers. We compared results of roentgenograms, leukocyte scans with indium In 111 oxyquinoline, and bone scans with the diagnostic criterion standards of bone histologic and culture findings. Leukocyte scans were repeated at 2- to 3-week intervals during antibiotic treatment. DESIGN: Cohort study. SETTING: Institutional and private, ambulatory and hospitalized patients. PATIENTS: Consecutive sample of 54 diabetic patients. Thirty-five patients with 41 foot ulcers were included. RESULTS: As determined by bone biopsy and culture, osteomyelitis was found to underlie 28 (68%) of 41 diabetic foot ulcers. Only nine (32%) of the 28 cases were diagnosed clinically by the referring physician. Underscoring the clinically silent nature of osteomyelitis in these ulcers, 19 (68%) of 28 occurred in outpatients, 19 (68%) of 28 occurred in ulcers not exposing bone, and 18 (64%) of 28 had no evidence of inflammation on physical examination. All patients with ulcers that exposed bone had osteomyelitis. Of the imaging tests, the leukocyte scan had the highest sensitivity, 89%. In patients with osteomyelitis, the leukocyte scan image intensity decreased by 16 to 34 days of antibiotic treatment and normalized by 36 to 54 days. CONCLUSION: The majority of diabetic foot ulcers have an underlying osteomyelitis that is clinically unsuspected. Leukocyte scans are highly sensitive for diagnosing osteomyelitis in diabetic foot ulcers and may be useful for monitoring the efficacy of antibiotic treatment. We recommend that diabetic patients with foot ulcers that expose bone should be treated for osteomyelitis. Diabetic patients with foot ulcers that do not expose bone should undergo leukocyte scanning, which eliminates the risk of bone biopsy in diagnosing osteomyelitis and allows for the diagnosis and treatment of this well-known but often silent precursor of lower extremity amputation.

Diabetes Mellitus, Type 2↗