An automated system for counting silver grains in autoradiographs

A system, incorporating a microscope, a television camera, and a small digital computer, has been developed for automated counting of silver grains in autoradiographs. The system has been designed specifically for analysis of experiments using the autoradiographic method of demonstrating axonal connections, although it should be adaptable to other uses.The system is capable of counting grains over stained sections up to a density of 300–500 grains/1000 sq. μm, depending on the grain size. Throughout most of this range, the accuracy of the counts is better than ± 10%. The counting algorithm is based upon the direct recognition of individual grains rather than on photometric measurements. This makes the counts relatively independent of grain size or shape, and permits accurate counts even though the grains occupy a layer of the emulsion thicker than the depth of focus of the objective. This is achieved by collating the counts obtained at different planes of focus on a grain-to-grain basis.Several automatic features, notably automatic focusing and stage movement, permit the counting of large areas of a section with minimal operator intervention. The system also includes features for the convenient identification of morphological landmarks in the section, and their correlation with the count data.There are several options available to the user which influence the accuracy and spatial resolutions of the output data and conversely the time required to count a large area. Because of these options the time required to count a 1 sq. mm area can vary from 2 to 8 h.     

A Prospective Evaluation of Nesiritide in the Treatment of Pediatric Heart Failure

This study sought to determine the potential of recombinant B-type natriuretic peptide (nesiritide) for the treatment of pediatric decompensated heart failure. Nesiritide is a widely used and effective treatment for decompensated heart failure (HF) in adults, but its safety and efficacy in pediatric patients is unclear. Outcomes of 55 separate nesiritide infusions of varying durations in 32 patients (13 males and 19 females; mean age, 8.01 years; range, 0.01–20.4) were evaluated prospectively. All patients received nesiritide in the intensive care unit. The starting dose (0.01 μg/kg/min) was titrated to a maximum of 0.03 μg/kg/min. All patients were monitored for clinical signs and symptoms, hemodynamics, urine output, electrolytes, oxygen requirements, and oral intake. Functional status was assessed by patients and/or their parents. All patients successfully underwent initiation and titration of nesiritide infusion. No hypotension or arrhythmias were noted during 478 cumulative days of therapy. Nesiritide was given safely with vasoactive medications. Mean urine output improved from 2.35 ± 1.71 cc/kg/hr on the day before nesiritide initiation (baseline) to 3.10 ± 1.94 cc/kg/hr on day 4 of treatment (p < 0.01). Serum creatinine decreased from 1.04 to 0.92 mg/dl (p = 0.096), mean central venous pressure from 13 to 7 mmHg (p = 0.018), and mean weight from 30.4 to 29.7 kg (p < 0.001) with therapy. Thirst, as subjectively assessed by patients old enough to respond, decreased with infusion in 31 of 42 cases (74%). Mean New York Heart Association functional class improved significantly (p < 0.001). Nesiritide infusion, alone or in combination, is a safe treatment for decompensated HF in pediatric patients. It is associated with decreased thirst and improved urine output and functional status, and it may be efficacious in the treatment of pediatric HF.     

Can Pleural Effusions Cause Tamponade-Like Effects?

Experimental studies have confirmed the clinical impression that large bilateral pleural effusions are able to raise the pressure in an otherwise hemodynamically insignificant pericardial effusion to a level sufficient to produce right ventricular diastolic collapse (RVDC). The hemodynamic consequences of this syndrome are not as severe as when the intrapericardial pressure is raised to the same level by excess intrapericardial fluid in the absence of pleural effusions. RVDC caused by excess pleural fluid with a minor pericardial effusion is a false positive indication for pericardial fluid drainage. Thoracentesis is more appropriate.     

The influence of preload and heart rate on Doppler echocardiographic indexes of left ventricular performance: comparison with invasive indexes in an experimental preparation

We evaluated the ability of Doppler echocardiography to assess left ventricular performance in six open-chest dogs studied under various conditions. Intravenous infusions of nitroglycerin were used to vary preload, atrial pacing was used to control heart rate, and changes in inotropic state were induced by two different doses of dobutamine (5 and 10 micrograms/kg/min iv) and by administration of propranolol (1 mg/kg iv). Left ventricular anterior wall myocardial segment length was used as an index of preload. Maximum aortic blood flow, peak acceleration of aortic blood flow, and dP/dt were measured with an electromagnetic flow probe around the ascending aorta and a high-fidelity pressure transducer in the left ventricle. A continuous-wave Doppler transducer applied to the aortic arch was used to measure peak aortic blood velocity, mean acceleration, time to peak velocity, and the systolic velocity integral. The differences between mean values obtained under different inotropic conditions were significant at the p less than .01 level for peak velocity and at the p less than .05 level for mean acceleration. Within a given animal, Doppler measurements of peak velocity correlated very closely with maximum aortic flow (r = .96), maximum acceleration of aortic flow (r = .95), and with maximum dP/dt (r = .92). Mean acceleration measured by Doppler echocardiography also correlated very closely with conventional indexes, but was subject to greater interobserver variability. Doppler measurements of time to peak and the systolic velocity integral correlated less well with conventional hemodynamic indexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

The shift in the relationship between intrapericardial fluid pressure and volume induced by acute left ventricular pressure overload during cardiac tamponade

We hypothesized that a process leading to an acute increase in cardiac size would change the relationship between intrapericardial pressure and fluid volume during cardiac tamponade, resulting in a change in the time of onset of right ventricular diastolic collapse (RVDC) as seen on the two-dimensional echocardiogram. Five spontaneously breathing dogs were instrumented to measure ascending aortic and right atrial blood pressures and intrapericardial pressure (IPP). A hydraulic occluder was placed around the proximal descending thoracic aorta. Each animal underwent six consecutive episodes of cardiac tamponade, three in the presence alternating with three in the absence of aortic constriction. The onset of RVDC was recorded and the volume infused into the pericardial space was measured. In the presence of aortic constriction, the relationship between pericardial pressure and incremental pericardial fluid volume was shifted so that IPP was an average of 3.4 mm Hg higher at any given intrapericardial fluid volume (p less than .001). At the onset of RVDC, the mean IPP was higher and the intrapericardial fluid volume was lower during aortic constriction than under control conditions (p less than .001 for both comparisons). Thus, a rapid increase in left ventricular volume in the presence of an otherwise unimportant pericardial effusion may increase intrapericardial fluid pressure sufficiently to cause RVDC.     

Digital processing of contrast echocardiograms: a new technique for measuring right ventricular ejection fraction

Imaging of the right ventricle with 2-dimensional echocardiography (2-D echo) is hampered by trabeculation of the right ventricular (RV) endocardial surface and by limited echocardiographic resolution. Determination of RV ejection fraction (EF) is thus often an inconsistent and tedious procedure. The process of digital subtraction contrast echocardiography was developed to maximize echocardiographic definition of the right ventricle and to assess RVEF with minimal operator interaction. Videotaped 2-D echocardiograms recorded during i.v. injection of agitated saline were digitized. Masks were constructed from end-systolic and end-diastolic apical 4-chamber and parasternal RV short-axis images. Masks were subtracted from corresponding images recorded with contrast in the right ventricle; images of the contrast alone were extracted and their areas determined. EF was calculated from raw area measurements and after conversion to volume. Comparison with RVEF measured by first-pass radionuclide angiography yielded the following correlation coefficients: 4-chamber RV area, r = 0.79; parasternal short-axis RV area, r = 0.59; ellipsoid approximation RV volume, r = 0.84; pyramidal RV volume, r = 0.79; and Simpson's rule triangular cylinder RV volume, r = 0.62. Digital subtraction contrast echocardiography is a new method that can be used for semiautomated determination of RVEF. Further studies to assess the clinical values of digital image processing of 2-D echocardiograms to measure RV function appear warranted.     

Diastolic rumbles in normally functioning porcine mitral valves

Fourteen of 22 patients (64%) with normally functioning porcine prosthetic valves in the mitral position had apical diastolic rumbles on phonocardiogram and by auscultation. Six (27%) had opening snaps. Factors necessary for the production of a diastolic rumble appear to include central flow, a flexible stent, and the presence of biologic material. Clinicians should be aware that diastolic murmurs and snaps occur in the normally functioning porcine valve.     

Expression of CXCL2 in the Serum and Cerebrospinal Fluid of Patients with HIV and Syphilis or Neurosyphilis

The potential mechanisms for blood–brain barrier damage and the diagnosis of neurosyphilis in HIV patients co-infected with syphilis (HIV-S) are unclear. The aim of the study was to determine the expression of CXCL2 in the serum and cerebrospinal fluid (CSF) of HIV-S patients. A total of 34 HIV patients and 7 controls were enrolled in a HIV clinical cohort for diagnosis of neurosyphilis in Taiwan. Serum and CSF concentrations of CXCL2 were determined by ELISA. Neurosyphilis was defined as a CSF white blood cell count of ≧20 cells/μl or a reactive CSF Venereal Disease Research Laboratory (VDRL). Demographics and medical histories were collected. All the patients with HIV-S were males. Most (80 %) had sex with men (MSM) and serum rapid plasma reagin (RPR) titers of ≧1:32. The medium age was 37 (range 21–68)?years. The medium CD4 T cell counts at the time of the diagnosis of syphilis were 299 (range 92–434)?cells/μl. Eight patients (24 %) had neurosyphilis based on a reactive CSF VDRL test (n?=?5) or increased CSF white blood cell counts of ≧20 cells/μl (n?=?3). The concentrations of CSF CXCL2 were significantly higher in patients with HIV and neurosyphilis as compared to HIV with syphilis, HIV, and controls (p?=?0.012). There were no significant differences in serum concentrations between the four groups. There was a correlation between CSF CXCL2 concentrations with neurosyphilis (p?=?0.017), CSF white blood cell count (p?=?0.001), and CSF protein levels (p?=?0.005). The CSF level of CXCL2 can be used to distinguish those with or without neurosyphilis in HIV infected patients.     

甘南地区儿童青少年近视筛查与矫正情况分析

目的:了解甘肃省甘南地区儿童青少年近视筛查与矫正情况,为近视的防控提供指导依据。方法:采用横断面分层整群抽样研究,抽取甘肃省甘南地区合作市和舟曲县2所幼儿园及12所中小学,每个年级随机抽取2个班,以整班为单位进行筛查,收集儿童青少年近视筛查及矫正情况进行统计学分析。结果:共抽取儿童青少年5 072人,剔除不合格记录后,最终纳入有效数据4 806例。总体近视患病率为45.55%,近视患病率随着年级的升高而呈现上升趋势(P<0.001),女生的近视患病率(48.66%)高于男生(42.18%)(P<0.001)。近视患病率随年龄增长呈现上升趋势(P<0.001),10-12岁为近视增长最快的年龄段,由25.62%增长至60.57%。随着年级的升高,中度近视和高度近视均呈现上升趋势(均P<0.001)。甘南地区总体戴镜率为28.55%,足矫率为50.72%,戴镜率随着学段升高呈现上升趋势(P<0.001),女生戴镜率(30.84%)高于男生(26.69%)(P=0.008)。初中学段低、中、高度近视的足矫率均为3个学段中最低。在各个学段中,高度近视的足矫率均最低...