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Biomedical subjects

S E Martin

Publications and source records attributed to S E Martin.

At least 73 records · Page 4Linked to original sources
PubMed1994

Defects on SPECT "perfusion" images can occur due to abnormal segmental contraction.

UNLABELLED: Technetium-99m-sestamibi images reflect tracer distribution at the time of injection. This "stay put" indicator allowed us to separate the effects of segmental left ventricular dysfunction per se versus myocardial blood flow on SPECT "perfusion" images in ten dogs. METHODS: An electromagnetic flow probe and hydraulic occluder were placed on the LAD coronary artery. Sonomicrometry was used to measure segmental wall shortening. At peak myocardial blood flow induced by adenosine, 35-45 mCi 99mTc-sestamibi were injected without occlusion. At 1 hr postinjection, during normal contraction, 40-50 msec end-diastolic and end-systolic SPECT images (#1) were acquired to reflect normal myocardial blood flow distribution. Later, during total LAD occlusion, and without reinjection of isotope, another gated scan (#2) was acquired. RESULTS: Coincident with abnormal contraction, large severe systolic defects [(28 +/- 5)% more severe compared to the baseline-scan #1; p < 0.01], and milder diastolic defects [(12 +/- 8)% more severe compared to the baseline-scan #1; p < 0.01] were observed during scan #2. Thus, abnormal contraction alone produced defects on SPECT images. CONCLUSION: Accordingly, defects in myocardial perfusion images must be interpreted as representing the integrated result of the combination of blood flow and segmental contraction heterogeneity.

Adenosine↗
PubMed1993

The special deterrent effects of a jail sanction on first-time drunk drivers: a quasi-experimental study.

This study examines the special deterrent effects of alternative sanctions on first-time offenders convicted of driving while intoxicated (DWI). It uses a quasi-experimental design based on the fact that in Hennepin County, Minnesota, some judges did not comply with the judicial policy that mandated a two-day jail sentence for all first-time DWI offenders. Data were collected on all drunk driving cases adjudicated by two judges during an 11-month period. One judge was known to sentence few first offenders to jail; the other was reputed to sentence virtually all first offenders to jail. Of the 383 offenders sentenced by the two judges, 60 were, reconvicted within the 23-month follow-up period. Using judge as an indirect measure of the jail sanction, we found no statistically significant difference in the recidivism rates of persons sentenced by the "jail" and "no jail" judges. Nor did the sanction have a direct effect. After statistically controlling for offender characteristics and prior traffic record, there was no significant difference between those sentenced to a fine (large or small) with no jail and those who were given a two-day jail sentence plus a small fine. Thus, a two-day jail stay is found to be no more effective in deterring subsequent drunk driving by convicted first offenders than an alternative monetary sanction.

Adult↗
PubMed1993

Intracoronary papaverine but not adenosine reduces regional ventricular function.

OBJECTIVES: Whether intracoronary papaverine or adenosine leads to reductions in regional left ventricular function was tested. METHODS: Fifteen anaesthetised dogs were prepared to record aortic pressure, left ventricular pressure dP/dt, electrocardiogram, regional ventricular shortening, and phasic and mean left circumflex coronary blood flow, and to give intracoronary boluses of papaverine (2, 4, or 6 mg) or adenosine (0.37 and 1.87 mg). RESULTS: Injected doses were chosen to mimic those given in the clinical setting. Papaverine (6 mg) reduced aortic pressure (mean 96(SD 17) to 89(18) mm Hg; p < 0.05), segmental shortening of the infused left circumflex zone (12(5) to 7(9)%; p < 0.05), and area of the pressure-length loop of the infused zone (120(71) to 53(47) mm.mm Hg; p < 0.05). Papaverine increased coronary blood flow (48(25) to 259(95) ml.min-1; p < 0.05), coronary vascular conductance (0.40(0.20) to 2.93(0.94) ml.mm Hg-1.min-1; p < 0.05), heart rate (88(27) to 100(28) beats.min-1; p < 0.05), and the segmental shortening (17(6) to 19(3)% p < 0.05) and area of the pressure-length loop (130(32) to 177(33) mm.mm Hg; p < 0.05) of the non-infused left anterior descending region. The hyperaemia elicited by papaverine was greater than that of reactive hyperaemia (p = 0.008). Papaverine also increased the QT interval corrected for heart rate (0.35(0.04) to 0.45(0.05) s; p < 0.05). When adenosine was given, coronary blood flow and coronary vascular conductance were increased to similar degrees as those during reactive hyperaemia (41(12) to 210(75) ml.min-1 and 0.46(0.14) to 2.43(0.83) mm Hg.ml-1.min-1, respectively; NS). No effects on segmental shortening or the area of the pressure-length loop in either zone were found. Also, adenosine had no effect on the QT interval. CONCLUSIONS: These adverse effects of intracoronary papaverine have important implications in its use in patients, particularly in those in whom abnormal cardiac function already exists. Adenosine, on the other hand, seems to be without deleterious effects.

Adenosine↗
PubMed1993

Sodium chloride, potassium chloride, and virulence in Listeria monocytogenes.

Virulence, as determined in a mouse model, and the virulence factor activities of catalase, superoxide dismutase, and listeriolysin O were examined in a parental strain (10403S) and in a nonhemolytic mutant strain (DP-L224) of Listeria monocytogenes. The cells were propagated in media containing various concentrations of sodium chloride or potassium chloride. Strains 10403S and DP-L224 exhibited significant increases in catalase activity and listeriolysin O activity when grown in medium containing either salt at 428 mM. The superoxide dismutase activities for both strains increased when they were grown in medium containing either salt. The superoxide dismutase activity was significantly increased only when cells were propagated in medium containing no salt compared with that when they were propagated in medium containing either salt at 1,112 mM. In addition, the listeriolysin O activity was highest for cells propagated in medium containing KCl at 428 mM, while the activity was significantly less for cells propagated in medium containing NaCl at an equal concentration. Virulence was examined in mouse livers and spleens after intravenous infection, and approximate 50% lethal doses were determined after intragastric and intraperitoneal infection. Each method of infection indicated that listeriolysin O is required for virulence, while growth in salt-containing medium or the production of higher levels of catalase, superoxide dismutase, and listeriolysin O do not appear to enhance the virulence of L. monocytogenes.

Animals↗
PubMed1993

Adenosine regulates coronary blood flow during increased work and decreased supply.

Adenosine may mediate coronary vasodilation during work-related hyperemia and during ischemia. We tested whether adenosine blockade with 8-p-sulfophenyltheophylline (PSPT) prevented dobutamine-induced hyperemia or magnified the reductions in flow due to vasopressin. Control (n = 8) and test (n = 7) dogs received paired infusions of dobutamine (70 micrograms/min iv for 5 min). Test dogs received PSPT (10 mg/kg iv) between doses. In both groups, paired infusions elicited comparable increases in oxygen consumption. However, in test dogs, the hyperemia was reduced significantly. Thus adenosine mediates the hyperemia of dobutamine. Separately, control dogs (n = 9) received vasopressin (0.6 microgram ic over 5 min); test dogs (n = 7) received PSPT before vasopressin. Vasopressin maximally increased coronary resistance by 3 min; effects were gone by 10 min. With PSPT, coronary resistance was increased further and remained high beyond 10 min. Thus adenosine-mediated vasodilation moderates the severity and duration of ischemia. These results indicate the importance of adenosine in mediating coronary flow during increased demand and reduced supply.

Adenosine↗
PubMed1993

Keratin intermediate filament expression in astrocytic neoplasms: analysis by immunocytochemistry, western blot, and northern hybridization.

In this study, 29 formalin-fixed, paraffin-embedded astrocytic tumors were analyzed immunocytochemically with the antikeratin monoclonal antibodies Mak-6 and Cam 5.2 and a polyclonal antibody against glial fibrillary acidic protein (GFAP). Immunoreactivity for Mak-6 was present in 29 cases (100%) including six well-differentiated astrocytomas, nine anaplastic astrocytomas, and 14 glioblastomas multiforme. Cam 5.2 immunoreactivity was focally present in one case of GBM (4%) but was absent in the remaining 28 cases. All cases were immunoreactive with an antibody against GFAP. Cytokeratin (CK) expression was examined in extracts of four separate well-characterized astrocytoma cell lines by Western blotting with the monoclonal antibodies Mak-6, Cam 5.2, and anti-CK 18 and by Northern analysis using a cDNA probe for the human CK 18 gene. The Western blots revealed the presence of immunoreactive bands corresponding to CK numbers 14/15, 16, and 18 in extracts from all four cell lines and additional bands corresponding to CK 8 in 3/4 lines and CK 19 in 1/4 lines. Northern analysis detected CK 18 mRNA in extracts from 2/4 astrocytic cell lines. These findings demonstrate that CK immunoreactivity is frequent in astrocytic tumors and confirm through the molecular and biochemical analysis of CK 18 gene expression and of keratin intermediate filament proteins that the basis for CK immunoreactivity in astrocytic tumors is bona fide CK expression, not cross-reactivity with other antigens or artifact. The demonstration of CK expression by astrocytic neoplasms has important implications for pathologists involved in the diagnosis of poorly differentiated tumors.

Antibodies, Monoclonal↗
PubMed1993

The use of fine needle aspiration cytology in the management of human immunodeficiency virus-related non-Hodgkin's lymphoma and Hodgkin's disease.

We prospectively studied the utility of fine needle aspiration (FNA) to diagnose non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) in patients with human immunodeficiency virus (HIV) infection and lymphadenopathy. Twenty-one patients with a clinical evidence of lymphoma underwent 24 FNA and site-specific tissue biopsies. Twenty-two of the 24 biopsy results were consistent with a malignant lymphoproliferative neoplasm: NHL (19 cases), HD (two cases), and T-cell lymphoma (one case). Two biopsies showed reactive lymphoid hyperplasia consistent with a clinical diagnosis of persistent generalized lymphadenopathy. There was an 87% correlation (21 of 24) between FNA and biopsy diagnoses. Eighteen of the 19 biopsy-confirmed NHL cases were diagnosed with FNA. Both cases of HD and the one T-cell lymphoma were also diagnosed with aspirate material. In conclusion, the FNA in HIV-infected individuals with suspected malignant lymphadenopathy is highly sensitive (95%). The FNA, when used in conjunction with the clinical appearance, is a useful tool in the management of HIV infection and lymphadenopathy.

AIDS-Related Complex↗
PubMed1993

Inhomogeneity of gated and ungated SPECT technetium-99m-sestamibi bull's-eyes in normal dogs: comparison with thallium-201.

By computer simulation, we have previously hypothesized, independent of the isotope imaged, that differences in view-to-view resolution and attenuation patterns predictably cause count density distortions in SPECT images. We tested the simulation predictions for both ECG-gated and ungated SPECT 99mTc-sestamibi and SPECT 201Tl myocardial perfusion images in normal dogs. In agreement with the predictions of the computer model, distortions in SPECT 99mTc-sestamibi myocardial perfusion images are virtually equivalent to SPECT 201Tl, dependent on the exact SPECT acquisition orbit and markedly different for a posterior 180 degrees acquisition arc compared to an anterior 180 degrees acquisition arc. Furthermore, ungated and gated SPECT 99mTc-sestamibi images show similar count inhomogeneities. These results suggest that little is to be gained from a 360 degrees acquisition with SPECT 99mTc-sestamibi, and that image distortions from gated or ungated SPECT 99mTc images with 180 degrees orbits will be similar to those in SPECT 201Tl images.

Adenosine↗
PubMed1992

A review of the fine-needle aspiration cytology findings in human immunodeficiency virus infection.

Patients infected with the human immunodeficiency virus (HIV) are subject to infections and neoplasms, which frequently result in palpable or radiologically identified masses. Fine-needle aspiration (FNA) offers a rapid, simple, and cost effective approach for diagnosis of these masses. During a 2-yr period, 396 aspirates were performed on 362 HIV-infected patients within the LAC-USC Medical Center. Adequate material was obtained from 84% of the FNA, allowing the etiology of the mass to be determined in 90% of the cases by means of a combination of cytologic, microbiologic, and immunocytochemical procedures. Significant pathologic processes identified in these patients by means of FNA included reactive lymphoid proliferations (35%), abnormal lymphoid proliferations (12%), infections (12.5%), cystic (5.5%) and inflammatory processes (5%), nonlymphoid malignancies (4%), and salivary gland pathology (1%). We conclude that FNA is an appropriate initial diagnostic procedure in HIV positive patients presenting with mass lesions.

Biopsy, Needle↗
PubMed1992

Comparison of single-photon emission computed tomographic (SPECT) myocardial perfusion imaging with thallium-201 and technetium-99m sestamibi in dogs.

OBJECTIVES: The purpose of the present study was to compare single-photon emission computed tomographic (SPECT) myocardial images of technetium-99m (Tc-99m) sestamibi and thallium-201 (Tl-201) isotopes in the same dog undergoing partial coronary occlusion during pharmacologic vasodilation. BACKGROUND: To date, no controlled study has been reported comparing SPECT Tc-99m sestamibi with SPECT Tl-201 imaging during stress with anatomic and physiologic standards. METHODS: Mongrel dogs were anesthetized with chloralose and instrumented to record left anterior descending coronary blood flow and aortic pressure. Partial coronary occlusion with a hydraulic cuff reduced coronary vascular conductance, which is equal to the coronary blood flow normalized to aortic pressure during peak vasodilation with intravenous adenosine. Each dog received 5 mCi of Tl-201, then 30 mCi of Tc-99m sestamibi during partial coronary occlusion at peak vasodilation. Tomographic myocardial imaging was performed in a 180 degrees anterior arc scan for 33.5 min, first with Tl-201, and later, without moving the dog, for 33.5 min with Tc-99m sestamibi. Postmortem staining defined the region underperfused because of its dependence on the artery that was partially occluded. RESULTS: In seven dogs with moderate reduction in coronary blood flow, coronary vascular conductance decreased with partial coronary occlusion (47 +/- 12%) during Tl-201 imaging and (47 +/- 8%, p = NS) during Tc-99m sestamibi imaging. The underperfused region was 23.9 +/- 6.4% of total left ventricular mass. Counts in the defects were 39% higher (0.86 +/- 0.08 of normal counts) for Tc-99m sestamibi than for Tl-201 (0.64 +/- 0.09 of normal counts, p < 0.001), and the defect on SPECT Tc-99m sestamibi images occupied only a fraction (0.37 +/- 0.30) of the area of the defect on the Tl-201 images of the same dog. Bull's-eye displays constructed from the pathologic slices showed that the Tl-201 defect size was closer to the underperfused region of the left ventricular mass determined pathologically than was the Tc-99m sestamibi defect size. In four additional dogs a severe, near total coronary occlusion was created during Tl-201 and Tc-99m sestamibi administration. In these dogs, similar defect contrast (0.55 +/- 0.12 vs. 0.62 +/- 0.09, p = NS) and areas (0.18 +/- 0.07 vs. 0.18 +/- 0.11, p = NS) were observed with Tl-201 and Tc-99m sestamibi, respectively. CONCLUSIONS: Tomographic myocardial imaging with Tc-99m sestamibi during moderately severe partial coronary occlusion underestimated the area of the defect relative to Tl-201 or to the pathologic reference standard in dogs. Defect contrast was sharper with tomographic myocardial Tl-201 than with tomographic myocardial Tc-99m sestamibi during moderately severe partial coronary occlusion.

Adenosine↗
PubMed1992

Neuropeptide Y and coronary vasoconstriction: role of thromboxane A2.

We previously reported that coronary constriction following neuropeptide Y (NPY) was alleviated by cyclooxygenase blockade. To determine the role of thromboxane A2 (TxA2), anesthetized dogs received two paired doses of NPY given 2 h apart. Nine control dogs received NPY alone. Nine test dogs received one of three TxA2 receptor antagonists given between the doses of NPY. Also, five dogs received NPY during which prostaglandins were measured. In controls, NPY decreased coronary blood flow and increased aortic pressure; coronary resistance was increased significantly. Heart rate fell, and myocardial oxygen consumption was unchanged. Thromboxane receptor blockers significantly relieved the coronary constrictor effect of NPY. The reduction in coronary blood flow was blunted, while heart rate, first derivative of left ventricular pressure, and myocardial oxygen consumption were unchanged. Alleviation by TxA2 receptor blockade paralleled that reported for cyclooxygenase inhibitors. Also, significant increases in coronary venous TxA2 were seen at the time of maximal increases in coronary resistance, while prostacyclin was unchanged. In summary, TxA2 appears to mediate part of the coronary constrictor effect of NPY.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Diagnosis of pulmonary blastoma by fine-needle aspiration biopsy: cytologic and immunocytochemical findings.

A preoperative diagnosis of pulmonary blastoma was established by fine-needle aspiration (FNA) cytology in a patient who presented with a pulmonary mass discovered incidentally on chest x-ray. At the time of computed tomography-guided FNA, an on-site preliminary diagnosis of poorly differentiated carcinoma was made after examination of a rapid hematoxylineosin (H&E)-stained smear. Malignant epithelial and stromal elements could be demonstrated on smears subsequently stained with the H&E, Papanicolaou, and Diff-Quik methods. The cell block preparation showed a distinctly biphasic malignant tumor with classic morphologic features of pulmonary blastoma. We present the clinical, cytologic, immunocytochemical, and histologic findings of this case and re-emphasize the valuable contribution of adequate cell block preparations to accurate diagnosis of fine-needle aspiration material.

Actins↗
PubMed1991

Fine-needle aspiration biopsy of malignant melanoma: a cytologic and immunocytochemical analysis.

The immunoreactivity of alcohol-fixed cell blocks from 15 fine-needle aspiration (FNA) specimens of malignant melanoma was investigated using monoclonal antibodies to keratin and vimentin intermediate filaments, melanoma cytoplasmic antigen (HMB-45), and S-100, as well as polyclonal antibodies to S-100. The results were compared with the immunoprofiles obtained using formalin-fixed surgical specimens from 10 of the same patients. In all cases, immunostaining for keratin was negative and immunostaining for vimentin was positive. Immunostaining for HMB-45 was positive in 13/15 aspirates and in 9/10 surgical specimens. Immunostaining for S-100 protein showed the greatest variability in staining, with 5/15 fine needle aspiration biopsies and 9/10 surgical specimens being positive using the polyclonal antibody and only 1/15 FNA specimens and 7/10 surgical specimens being positive using the monoclonal S-100 reagent. Our findings indicate that immunocytochemical studies can be very useful as an adjunct in the FNA diagnosis of melanoma. Also included in our series is an unusual variant of malignant melanoma, the so-called signet ring melanoma. Given the location of the anal verge, the use of immunocytochemical markers was essential in establishing the correct diagnosis in this case. While S-100 protein is of limited value as a marker of melanoma in alcohol-fixed FNA specimens, a definitive diagnosis of malignant melanoma can be made using a panel of antibodies including keratin, vimentin, and HMB-45.

Adult↗
PubMed1991

Cocaine-associated thrombocytopenia.

In this retrospective report, four male intravenous cocaine users are described with thrombocytopenia temporally related to the use of the drug. Mucosal bleeding and megakaryocytic hyperplasia occurred in all patients. The cocaine-thrombocytopenia relationship was especially apparent in one individual who developed thrombocytopenia on two separate occasions after intravenous cocaine use. Three patients were treated successfully with high doses of intravenous gamma globulin and steroids, while one patient required splenectomy. Along with the widespread use of cocaine in our society has come the recognition of a number of adverse effects of the drug. Thrombocytopenia may be added to a list that includes myocardial infarction and central nervous system complications.

Adult↗
PubMed1991

Adenosine receptor blockade with 8-p-sulfophenyltheophylline aggravates coronary constriction.

We examined the role of adenosine in modulating the coronary constrictor effect of neuropeptide Y (NPY). Anesthetized dogs (n = 22) were instrumented to record hemodynamics and to collect arterial and coronary venous blood. In control dogs (n = 7), during the first 30 min before NPY, baseline coronary resistance fell slightly. By 10 min after NPY (42 nmol over 4 min), coronary resistance was increased by 30% and fell slowly to pre-NPY levels over the ensuing hour. Intravenous (7.5 mg/kg, n = 3) or intracoronary (to 100 microM arterial concentration, n = 12) infusion of 8-p-sulfophenyltheophylline (8-THEO) blocked the vasodilator effects of adenosine but did not alter the peak dilation seen with papaverine or reactive hyperemia. Over 30 min before NPY, infusion of 8-THEO increased baseline resistance by 31% as it reduced coronary blood flow, despite no change in other hemodynamic parameters or myocardial oxygen consumption. The coronary constrictor effect of NPY was magnified in the presence of adenosine receptor blockade. At 3 min, coronary resistance was increased by 34%, at 5 min by 52%, and at 10 min by 59%. The effect of adenosine receptor blockade on constriction due to NPY could not be attributed to a nonspecific alteration in cardiac function or oxygen consumption. In addition, the increase in baseline coronary resistance following receptor blockade correlated with the worsening of the coronary constriction following NPY (r = 0.48, P less than 0.05). Thus it appears that adenosine modulates an imposed constriction of coronary vessels and acts as a "host defense" to restore coronary tone toward normal.

Adenosine↗