Simple Non-invasive Technique Research Articles

Bone marrow transplantation: effects of conditioning and cyclosporin prophylaxis on microvascular permeability to a small solute (technetium 99m diethylene triamine penta-acetic acid)

Microvascular permeability to small diffusible solutes has rarely been measured at a clinical level. We have developed a simple non-invasive technique for measuring the permeability surface area (PS) product, which is suitable for clinical use. We illustrate its potential value in six subjects who underwent bone marrow transplantation for chronic myeloid leukaemia. These patients received high-dose cyclosporin A (CyA) for prevention of graft versus host disease (GVHD) and sustained an easily measurable increase in microvascular permeability to technetium 99m diethyltriamine penta-acetic acid (99mTc-DTPA). This was measured as the PS product, which increased from 1.1 (SD 0.3) to 2.2 (0.4) ml/min per 100 ml tissue between baseline and treatment with CyA for prevention of GVHD (P less than 0.01). The increase broadly correlated with nephrotoxicity which was measured, from the plasma DTPA clearance, as global glomerular filtration rate (GFR). This decreased from 106 (11.1) to 49 (6.7) ml/min (P less than 0.001). These abnormalities, both in PS product and GFR, were sustained for several months, after which they tended to return towards baseline levels. We conclude firstly that this technique has a potential clinical role and secondly that endothelial abnormalities due to CyA deserve further study.

Apolipoprotein E genotyping using the polymerase chain reaction and allele-specific oligonucleotide primers.

A method for apolipoprotein (apo) E genotyping was developed using the polymerase chain reaction (PCR) with allele-specific oligonucleotide primers (ASP). Synthetic oligonucleotides with base-pair mismatches at the 3' terminus were used as primers to amplify the apoE gene in subjects previously phenotyped using isoelectric focusing (IEF). Complementary primer-allele combinations were specifically amplified by PCR, together with a control pair of primers specific to the human prothrombin gene. Identification of genotype by PCR using ASP was consistent with the phenotypes that were determined by IEF for 14 healthy normolipidemic subjects. These results were achieved using DNA isolated from buccal epithelial cells obtained from a mouthwash or DNA extracted from leukocytes. Genotype identification required analysis of the PCR products on an ethidium-stained agarose gel, yielding results 3 h after DNA extraction. In comparison with other current methods, PCR using ASP is suggested as a rapid and simple noninvasive technique for determining population apoE allelic distribution.

Photoelectric Plethysmography in Monitoring Skin Circulation

Photoelectric plethysmography is not new, but is a simple noninvasive technique to determine erythrocyte volume and oxygen saturation. The data are immediately available, accurate, repeatable, and recordable. Methods currently used for estimating microcirculation and oxygen saturation include clinical tests such as observation of skin color, temperature changes, capillary refill, and bleeding; chemical tests such as fluorscein injection; radioactive isotopes (24Na, 131I, 99mTc, and 133Xe); and instrumental methods (both invasive and noninvasive) such as temperature and infrared thermometry, thermocouples, oxygen probes, and/or the plethysmometer. None of these methods is entirely satisfactory.

Cardiopulmonary Exercise Testing

Cardiopulmonary exercise testing is an objective method of assessing the functional capacity of a patient. In contrast to clinical assessment and resting investigations, exercise testing is useful in detecting early changes in patients with cardiac or respiratory disease. Although a number of different types of ergometers can be used for testing, the ones used commonly are the cycle and treadmill. Comparison of these two modes of exercise shows no significant clinical difference between them; therefore, either can be used for routine cardiopulmonary exercise testing. There are various types of exercise protocols, but generally the protocol should involve large muscle groups and should be tolerated by the population being tested. The main goal when selecting an exercise protocol is to strike a balance between workload increments that do not prematurely fatigue the subject and at the same time allow the subject to reach a maximum power output within 8 to 15 minutes. Whatever the exercise test protocol used, the intensity should be increased to a symptom-limited maximum. This procedure is safe as long as contraindications for starting a test and indications for terminating a test are adhered to strictly. The assessment of cardiorespiratory responses during exercise ranges from simple and noninvasive techniques to those that are invasive and complex. In the majority of cases all the information needed for proper assessment of the patient can be acquired with simple noninvasive techniques.

Flexitherm Liquid Crystal Contact Thermography: A simple non-invasive technique for detection of deep venous thrombosis

Flexitherm Liquid Crystal Contact Thermography: A simple non-invasive technique for detection of deep venous thrombosis

Simplified assessment of arterial graft patency using indium-labelled-platelet scintigraphy.

Arterial grafts were studied with indium-III-labelled platelets in 13 patients (18 graft limbs) in the early post-implication period. Platelet thrombogenic activity was graded into four grades by visual inspection of the images, and scintigraphic criteria of impending graft occlusion were defined. Dacron and polytetrafluoroethylene grafts had similar high thrombogenic activity in comparison with autologous veins. Nine graft studies showed patterns of radioactivity concentration that suggested threatening thrombosis and eight of these eventually occluded. In nine other studies absent to moderate radiolabelled platelet activity was observed and none occluded within a mean follow-up period of 24 months. Prediction of graft occlusion of scintigraphic evaluation using the present simple non-invasive technique is valuable since corrective measures may be instituted earlier and with greater success in the post-operative follow-up period.

Cross-orientation inhibition in cat is GABA mediated.

Visual evoked potentials (VEPs) were recorded from cat cortex (area 17) before, during and after application of the GABA blocker bicuculline (iontophoretic or topical). The stimuli comprised a test sinusoidal grating, and a mask grating oriented either parallel or orthogonal to the test. Both test and mask alternated in contrast at different temporal frequencies. VEPs were averaged in synchrony with the test contrast reversal, so the mask did not contribute directly to the averaged VEP response. Before application of bicuculline, both parallel and orthogonal masks attenuated the amplitude of VEPs and changed the phase response, but in different ways. Orthogonal masks lowered the slope of the contrast response curve without affecting extrapolated threshold, while parallel masks caused the curve to shift to the right. Orthogonal masks increased the phase advance, while parallel masks eliminated it. During application of bicuculline, neither parallel nor the orthogonal masks attenuated VEP amplitudes. The results suggest that although the mechanisms for the action of parallel and orthogonal masks are clearly distinct, both are mediated by the GABA-ergic inhibitory system. Given this evidence, measurement of VEP contrast response curves may provide a simple non-invasive technique for monitoring visual inhibition in humans.

Inside a quantitative analysis of in vivo near infrared monitoring.

Measuring human brain function is one of the most formidable scientific/engineering endeavours. Recently spectacular methods such as CT, NMR and PET have eclipsed the importance of relatively simple continuous non-invasive techniques based on the analysis of electromagnetic signals and/or optical features of brain tissue.

Phonoechocardiography and intracardiac phonocardiography in hypertrophic cardiomyopathy.

The salient phonoechocardiographic features of patients having hypertrophic cardiomyopathy (HCM) with or without left ventricular outflow tract (LVOT) gradients are reviewed. Intracardiac sound and pressure recordings from high fidelity catheter-tipped micromanometers have documented that the precordial murmur is the summation of both the systolic ejection murmur (SEM) arising from the LVOT, as well as the mitral regurgitant murmur recorded from the left atrium. The intensity of the precordial murmur varies directly with the LVOT gradient, which in turn is determined primarily by the contractility and loading conditions of the left ventricle. Reversed splitting of the second heart sound (S2) with paradoxical respiratory movement is a common finding in HCM, and when present, almost always denotes a significant LVOT gradient. It is due to marked lengthening of the left ventricular ejection time secondary to prolongation of the contraction and relaxation phases of left ventricular systole. The presence of a fourth heart sound (S4) is the rule in HCM when normal sinus rhythm is present, and is a reflection of a forceful left atrial contraction into a hypertrophied noncompliant left ventricle. A third heart sound (S3) is also common in HCM, and often the initial vibrations occur before the 0 point of the apexcardiogram (ACG) and continue giving the auscultatory impression of a diastolic rumble. When associated with a loud S1, which is frequently present, the clinical presentation may mimic mitral stenosis. This is particularly true when the patient has chronic atrial fibrillation. Careful attention to evidence of marked left ventricular hypertrophy as well as the typical echocardiographic findings of HCM preclude this diagnosis. In conclusion, phonoechocardiography is a simple non-invasive technique which almost always makes the definitive diagnosis of HCM.

Ajmaline-induced electrocardiographic changes in chronic Trypanosoma curzl-infected rats

In the present study, the ajmaline test was applied to T. cruzi-infected rats and evaluated for the ability to reveal ECG disturbances. The test consists of intravenous injection of ajmaline (2 mg/kg body-weight) under ether anaesthesia, and continuous ECG monitoring (right precordial lead: V 1 or V 2, 100 mm/sec paper speed). The animals used for the test (n = 30) had been experimentally infected with the Colombia strain of T. cruzi (1,000 parasites/g body-weight, newly weaned rats) one year before the experiments. Control non-infected rats (n = 21) were similarly maintained and treated. The ECGs were analysed under baseline conditions, i.e., before ajmaline, and 15, 30, 60 and 180 seconds after completion of ajmaline injection through the dorsal vein of the penis. The following parameters were studied: heart rate, PR interval, QRS and Qat duration. Morphological changes of the QRS complex and ST-T segment were also recorded. Under baseline conditions, the two groups had comparable values for all parameters, except for the PR interval, which was significantly increased in infected rats. No changes in wave rhythm or morphology were detected under baseline conditions. The PR and QaT intervals and QRS duration were significantly longer in both groups after ajmaline injection, at all periods studied. When the two groups were compared for relative variations, consistently and significantly higher alterations (p<0·05) were observed in the T. curzi-infected group, except for the QaT interval at 180 seconds. However, the severe rhythm and ventricular conduction disturbances detected in 30% of the infected rats represented clear-cut discriminative alterations. These results show that the ajmaline test can be an effective tool for detecting potentially cardiopathic T. curzi-infected rats by a relatively simple non-invasive technique, thus providing new possibilities for the study of experimental Chagas' heart disease in this animal model.

An objective study of the dimensions of the ischial pressure point and its correlation to the occurrence of a pressure sore

A simple non-invasive technique has been used to study the dimensions of the ischial pressure point in normal and paraplegic individuals. The same technique charts the surface area of the gluteal impression. The data obtained in these two groups of patients (normal and paraplegic) have been analysed to see if it is possible to predict the greater susceptibility of certain individuals to suffer from pressure sores over the ischial tuberosity.

Ultrasound scanning of the ovarian cycle.

Ultrasound scanning of the ovarian cycle is a simple noninvasive technique for monitoring ovarian activity. It helps to predict a mature follicle and the time of ovulation more accurately than the basal body temperature and more rapidly and cheaply than a hormone profile, but still only one facet of ovarian activity. With respect to in vitro fertilization, egg collection can be undertaken by means of sonically guided puncture via the bladder, which is reported later in this issue. Replacement of the embryo can be controlled by sonar visualization of catheter. The use of ultrasound has proved to be extremely helpful in the management of the infertile couple.

Recent advances in clinical assessment of control of breathing

In the present review I have attempted to show that the use of simple noninvasive techniques and careful analysis of the breathing pattern has led to new hypotheses about the disorder in ventilatory control in patients with respiratory disease. Clearly, further investigation is needed before this complicated aspect of respiratory physiopathology is fully understood. Nevertheless, recent advances in this field have provided enough information to allow the emergence of a more coherent picture. Thus, while many problems remain, the questions to be pursued in future research have been somewhat clarified.

Determination of gastric-emptying profiles in the rat: influence of oil structure and volume

A simple non-invasive technique was developed for the determination of the gastric-emptying rate of oils in rats, employing a gamma camera and 99mTc-sulphur colloid as the oil phase marker. Using this method the gastric emptying of 3 oils, arachis oil, Miglyol 812 and liquid paraffin, was investigated. It was shown that both the oil volume and chemical structure altered the rate of gastric emptying.

Gastrointestinal passage of [125I]Na and blood clearance of125I-labelled bacteria recorded with a simple non-invasive technique

Gastrointestinal passage of [¹²⁵I]Na and blood clearance of¹²⁵I-labelled bacteria recorded with a simple non-invasive technique

Gastrointestinal passage of [125I]Na and blood clearance of 125I-labelled bacteria recorded with a simple non-invasive technique

Gastrointestinal passage of [125I]Na and blood clearance of 125I-labelled bacteria recorded with a simple non-invasive technique

CT determination of renal and hepatic microvascular volumes in experimental acute renal failure.

Alterations in renal blood flow are considered to play an important role in the pathogenesis of acute renal failure. Most techniques designed to assess organ blood flow and microcirculatory disturbances are relatively invasive and cumbersome. This study describes a noninvasive method for the determination of an organ's fractional vascular volume (FVV)-the fraction of an organ occupied by blood vessel lumen. It utilizes computed tomographic (CT) scanning and a contrast agent, perfluoroctylbromide (PFOB), which remains intravascular and is not excreted by the kidney. Acute renal failure (ARF) was induced in rats by intraperitoneal injection of glycerol (5 g/kg). CT scans of kidneys, liver, and heart were performed prior to and following intravenous administration of PFOB. FVV of kidney and liver were calculated prior to induction of ARF and at selected time periods following ARF (20-50 minutes and 60-120 minutes). FVV of the kidney decreased significantly 20-50 minutes following ARF and had returned to control values at 60-120 minutes. Renal histologic abnormalities were more severe at the later time period. Thus, early alterations in blood flow precede pathologic abnormalities in the kidney following glycerol-induced ARF. Determination of an organ's fractional vascular volume is a simple noninvasive technique which provides useful information on the microcirculation during the course of experimental disease.

Failure of iosulamide to enhance hepatic tumors in rats.

Iosulamide, an experimental cholangiographic agent recently being evaluated for hepatic contrast enhancement in computed tomography, has been investigated in the rat for the differential enhancement between the liver and three histologically different experimental tumors (a well differentiated mammary adenocarcinoma, a poorly differentiated colon carcinoma, and a hepatoma). After intravenous injection of iosulamide in dosages of 140 and 280 mg iodine per kg, iodine concentrations were determined in blood, liver and tumors at 1, 5, 10, and 30 minutes, using x-ray energy spectrometry. Compared with the surrounding liver parenchyma, the iodine concentrations were generally higher in the breast carcinoma. With respect to the liver, iodine concentrations varied greatly in the colon carcinoma and hepatoma. The iodine washout from all three tumors was relatively slow. Since the distribution volume of cholangiographic contrast agents includes both vascular and interstitial space, the relatively high and prolonged iosulamide accumulation in tumors can be explained by a relatively large interstitial compartment, which is apparently characteristic of neoplastic lesions. This, together with the modest iodine concentrations found in the liver, suggests that iosulamide is of little use in computed tomography for the differential enhancement of liver and hepatic tumors.

Penile flow index and its role in classification of erectile dysfunction: a preliminary report.

A method is described to confirm vascular disorders in sexual impotence by a simple noninvasive screening technique. Doppler ultrasound signals are registered from superficial dorsal penile arteries and arteria radialis. The penile flow index (PFI) is determined by dividing the mean values of both measurements. An insufficient vascular support of the penis is assumed if the amplitude of the dorsal penile arteries is less than one third of that of the a. radialis. Identical Doppler signals are registered in superficial dorsal and deep cavernosal arteries.

Noninvasive evaluation of peripheral arterial disease in the geriatric patient.

A progressive increase in the incidence of peripheral arterial occlusive disease is being observed in today's steadily aging population. In recent years, a number of simple noninvasive vascular techniques have become available for the diagnosis of peripheral arterial occlusive disease. These techniques provide the physician with physiologic information about the patient's peripheral circulation which permits discrimination between complaints compatible with the aging process and those indicative of an underlying disease state. This article reviews the noninvasive vascular diagnostic techniques that the authors found useful in evaluating the geriatric patient. These include oculoplethysmography. Doppler ultrasound, photoplethysmography, arterial impedance plethysmography, and electromagnetic flowmetry.