Evanescent cavity ring-down spectroscopy (e-CRDS) of hemoglobin absorption at the silica-water interface.

The absorption of hemoglobin (Hb) from controlled urine samples was observed using the technique of evanescent cavity ring-down spectroscopy (e-CRDS). A room temperature, alexandrite laser pumped LiF:F2(+**) color-center pulsed laser was used to excite Hb at 425 nm. A minimum absorbance level of 2.57 x 10(-4) was achieved corresponding to a minimum detectable concentration of Hb in urine of 5.8 nM. These levels could have advantages in the diagnosis of hemoglobinurea. The formation of layers of Hb upon the silica surface allowed for an increased sensitivity for smaller concentrations of Hb than would be expected for only a free floating solution. The formation of the layers also suggested a higher binding constant of Hb to the silica surface than between other layers of Hb molecules. Future studies are underway to understand the effects of salinity on the observed absorption due to the competitive binding of Na+ to the surface. Absorption isotherm modeling will also be used to better understand the development of layers upon the surface.

Spectrum of general surgery in rural America.

OBJECTIVES: To define the types of surgery performed by rural surgeons, to compare their experience to that of graduating US surgical residents and to document rural surgical mortality. DESIGN: Prospective registry of consecutive cases recorded by 7 rural general surgeons working in one department of surgery from December 31, 1994, through March 30, 1996. Comparison with the 1995 Report C (Resident Operative Logs) of the Residency Review Committee. National survey of surgical residency programs regarding formal gynecology experience. SETTING: Nine rural community hospitals in the Midwest. PATIENTS: Patients undergoing surgery in 9 cities with populations of fewer than 10000. MAIN OUTCOME MEASURES: Type of surgery and postoperative (30-day) mortality. RESULTS: Two thousand four hundred twenty procedures were performed by 7 surgeons practicing in 9 cities with populations of 1500 to 8000. There were 6 (0.25%) postoperative deaths. Case types are as follows: endoscopy, 686 (28.3%); gynecology, 498 (20.6%); hernia, 241 (10%); colorectal, 194 (8%); biliary, 183 (7.6%); cesarean sections, 130 (5.4%); breast, 129 (5.3%); orthopedic, 115 (4.8%); carpal tunnel, 63 (2.6%); otolaryngology, 35 (1.4%); and endocrine, 1 (0.4%); for a total of 2420 (100%). Report C indicated 1995 graduating chief residents averaged 8 obstetric and and gynecologic and 5.3 orthopedic cases during their residency. Of 204 surgical residency programs surveyed, 106 (52%) offered no obstetrics and gynecology rotation. CONCLUSIONS: A large volume of surgery was performed with low mortality by 7 rural general surgeons. The operative experience of 1995 residency graduates differed from our rural surgeons. We recommend a rural surgical track in selected training programs to prepare graduates better for rural practice. Senior level rotations in endoscopic, gynecologic, obstetric, and orthopedic surgery and mentorship with rural surgeons would be optimal.

A serological survey of bovine herpesvirus-1 infection in selected dairy herds in northern and central Italy.

Serum samples from a total of 6979 dairy cattle from 55 herds in northern Italy (51 herds) and central Italy (4 herds), were examined by the serum neutralization test for the presence of antibody to bovine herpesvirus-1 (BHV-1). It was found that 84.31% of the farms selected in northern Italy and all the farms from central Italy had seropositive animals at titers of 1:4 or higher. The prevalence of infection was essentially the same among the cattle populations of the two selected areas of the country, being of 34.99% in the north and of 38.65% in central regions. A comparison of the data from the present study with those obtained in a serological survey conducted in Italy in 1966, shows that the rate of seropositive cattle to BHV-1 has increased by about 5.0% in the last 30 years.

Respiratory infections of sheep.

Sheep respiratory infections appear as differing clinical syndromes. Mild, acute infections are usually due to parainfluenza 3 (PI3) virus. A mild but chronic respiratory problem in lambs under 1 year old is thought to be caused by Mycoplasma ovipneumoniae probably in association with Pasteurella and PI3. Acute bacterial pneumonia usually results from infection with Pasteurella of biotype A. Infection with PI3 can initiate invasion by Pasteurella. Bordetella parapertussis infection has also been implicated. Serotypes of biotype T P. haemolytica cause an acute septicaemia. Stressful management practices may be a predisposing factor. Chronic proliferative pneumonia results from infection by retroviruses of pulmonary adenomatosis or maedi-visna. Both infections have incubation periods extending into years. The former produces fatal tumorous masses in the lungs. Diagnostic tests are being actively sought. Maedi-visna can present as several clinical problems, frequently as an insidious but fatal proliferative pneumonia.

Comparison of two noninvasive screening tests for renovascular hypertension.

OBJECTIVE: To compare and contrast the diagnostic accuracy rates of two newer noninvasive screening tests for renovascular hypertension, the most common curable cause of secondary hypertension. PATIENTS AND METHODS: One hundred fifty patients, thought to have a high probability of renovascular hypertension by established clinical criteria, underwent both the captopril challenge test and the renal scintigram with angiotensin-converting enzyme inhibitor, while on their usual antihypertensive regimen except angiotensin-converting enzyme inhibitors. If the result of either test was abnormal, angiography was undertaken, followed immediately by angioplasty (if a stenosis was found) or by renal vein renin determinations. Patients whose blood pressures were lower 6 to 12 weeks after a revascularization procedure (surgery or angioplasty) were diagnosed as having renovascular hypertension. RESULTS: Of the 150 patients, 100 underwent angiography, and 59 had renal artery stenosis. Of 53 patients who had surgery (n = 21) or angioplasty (n = 32), 51 had lowered blood pressures compared with before the procedure. Sensitivity and specificity of the tests were as follows: renal scintigram with angiotensin-converting enzyme inhibitor: 92% and 91% (all patients) and 92% and 80% (only patients with angiograms); captopril challenge test: 76% and 82% (all patients) and 76% and 58% (only patients with angiograms). Little difference in accuracy rates was observed in subgroup analyses in patients with chronic renal impairment, previous diuretic or beta-blocker therapy, or bilateral renal artery stenosis. CONCLUSIONS: In selected, treated patients with a high probability of renovascular hypertension, the renal scintigram with angiotensin-converting enzyme inhibitor was a more accurate noninvasive screening test than the captopril challenge test. Noninvasive screening tests for renovascular hypertension can help to identify patients who should undergo angiography and often predict success after revascularization.

Role of CD4+ (helper) T cells in the pathogenesis of murine cytomegalovirus myocarditis.

Murine cytomegalovirus causes diffuse myocardial lesions in immunologically intact young adult male BALB/cBy mice. The cardiac changes develop in and around the small penetrating blood vessels of the heart where perivascular and interstitial infiltrates of macrophages and lymphocytes accumulate. Focal lesions of the coronary vessels and the endocardium also appear. When infected mice are depleted of CD4+ T lymphocytes, myocardial lesions fail to develop even though virus replication in the heart is enhanced. Contrary wise, when CD4+ cells are adoptively transferred into infected, thymectomized, irradiated, bone marrow-repleted mice, focal perivascular necrotizing lesions of the heart develop. Depletion of CD8+ T lymphocytes fails to influence virus replication and the development of cardiac lesions. Endothelial and endocardial cells appear to be major sites of virus replication in the heart. Delayed hypersensitivity is hypothesized to be the mechanism of cardiac injury in this model system.

Murine cytomegalovirus myocarditis.

Murine cytomegalovirus infects a variety of organs after inoculation into adult male mice. We have established a model of myocarditis in which focal lesions from adjacent to virus-infected endothelial cells. The development of the myocarditis is mediated by CD4+ helper T cells. The lesions fail to develop when these cells are eliminated from the animal by administration of a specific monoclonal antibody. Alternatively, repletion of thymectomized, irradiated and bone-marrow reconstituted animals with CD4+ cells results in myocarditis. The evidence, although incomplete, suggests that a delayed hypersensitivity response is the pathogenetic mechanism involved.

A serological comparison of some animal herpesviruses.

Bovine herpesvirus 1 (BHV-1) isolates (Cooper-type strain 4975 and Oxford) were compared in neutralization tests with the bovine herpesvirus 4 (BHV-4) isolate (85/16 TV) and the herpesviruses of red deer (D2839/1) and goats (E/CH). Hyperimmune antiserum was prepared in rabbits against the plaque-selected viruses and endpoint and kinetic neutralization test were made. BHV-4 was clearly different from the other four viruses. The closely-related BHV-1 strains were also related in these tests to the red deer herpesvirus. The Oxford strain seemed rather closer antigenically than the Cooper-type strain to the red deer herpesvirus. Antiserum to the caprine herpesvirus failed to neutralize either BHV-1 strain or red deer virus, but antiserum to the Cooper-type and red deer herpesviruses did neutralize caprine virus to a limited extent.

Planar positron imaging of rubidium-82 for myocardial infarction: a comparison with thallium-201 and regional wall motion.

Rubidium-82 (Rb-82) is a generator-produced, short half-life (76 seconds) positron emitting potassium analog. Using a mobile gamma camera equipped with a rotating tungsten collimator and high-energy shielding, we examined the use of Rb-82 in the coronary care unit and clinical laboratory for detection of perfusion defects due to myocardial infarction. We studied 31 subjects, 10 patients with acute myocardial infarction, 12 with remote myocardial infarction, and nine controls. Rb-82 images were compared with Tl-201 and regional wall motion for detection of infarct-related arteries. Of the 22 patients with myocardial infarction, 16 were identified with Rb-82 and Tl-201. In nine control subjects, eight were normal with each method. Correlation between Rb-82 and Tl-201 defect scores was excellent. Sensitivity and specificity for infarct-related arteries were similar for Rb-82, Tl-201, and wall motion imaging. Thus planar Rb-82 imaging can detect MI reliably in the coronary care unit and in the clinical laboratory.

Combined bone marrow and gallium imaging. Differentiation of osteomyelitis and infarction in sickle hemoglobinopathy.

The clinical records and scintigrams of patients with sickle hemoglobinopathy who underwent combined Tc-99m bone marrow imaging and Ga-67 imaging to differentiate osteomyelitis from bony infarction were reviewed. Of 18 paired examinations in 15 patients, osteomyelitis was diagnosed correctly in six cases; in all six, gallium uptake at the symptomatic site was incongruently increased relative to the bone marrow activity. Of the 12 episodes of infarction, 11 showed congruent activity on both Tc-99m and Ga-67 images. The remaining study was interpreted incorrectly as osteomyelitis due to incongruent Tc-99m and Ga-67 uptake. The use of sequential Tc-99m bone marrow and Ga-67 imaging is an effective means of distinguishing osteomyelitis from bony infarction in patients with sickle hemoglobinopathy.

The effect of previous thoracic surgery on gallium uptake in the chest.

To determine the frequency, average duration, and characteristic patterns of persistent gallium uptake caused by thoracotomy, serial postsurgical scans of 51 patients were reviewed. In each of these cases a thoracotomy had been performed for resection of lung cancer, and there had been no evidence of recurrent tumor for at least 2 yr following surgery. Postoperative gallium activity due to non-neoplastic postoperative changes occurred in 15 patients. Five of six patients scanned within 3 mo of surgery and six of 21 scanned 3 to 6 mo following surgery showed persistent uptake at the operative site. All 13 patients who had subsequent scans demonstrated eventual clearing. Activity persisted more than 18 mo postoperatively in only one patient. Patterns of gallium accumulation included both focal chest wall uptake at the incision site and diffuse pleural activity.

Scintigraphy with gallium-67 citrate in staging of soft-tissue sarcomas of the extremity.

We performed a retrospective study of sixty patients who had a soft-tissue sarcoma of the extremity to determine the usefulness of scintigraphy with gallium-67 citrate as a staging modality. Abnormal activity of the gallium was present in forty-one of forty-eight sites in which there was macroscopic primary tumor. In six of the forty-eight patients, the imaging demonstrated non-pulmonary metastases that had not been detected by any other staging studies. Scintigraphy with gallium-67 citrate should be employed routinely for staging of soft-tissue sarcomas because of its utility in detecting non-pulmonary metastases that are not otherwise detected on routine staging studies.

Cardiac gallium uptake in doxorubicin-induced cardiotoxicity.

Cardiac uptake in a patient with doxorubicin-induced cardiotoxicity is described. Follow-up examination with Ga-67 after clinical improvement of symptoms demonstrated lessened cardiac uptake.