Model identification and estimation of organ-function parameters using radioactive tracers and the impulse-response function

Examination of the input-output events in functioning organs by the use of the impulse-response function (IRF) for a radioactive tracer is gaining more and more ground in nuclear medicine. This study summarizes the development of deconvolution analysis, laying special stress on the model-free approach. System linearity and time invariance are discussed, and means of eliminating noise in IRFs originating from the input and organ-time-activity curves are outlined. Typical IRFs are illustrated by flow diagrams, time-domain curves, and their representation by Laplace transforms. The cases of nondiffusible and diffusible tracers as well as parenchymally extracted and transported substances are discussed. Methods for the derivation of models and for the calculation of physiologically important parameters from theIRFs are suggested.At present, a guest scientist at the Institute for Medicine, Nuclear Research Center Jülich, Jülich, Federal Republic of Germany     

Dense osmiophilic material in the surface of the olfactory bulb in the teleost Cyprinus carpio L

A dense osmiophilic structure was found associated to the basal lamina of the outer limiting glial membrane of the carp olfactory bulb. In certain sections this material appears as "beads" composed of small strand-like structures, and in others it seems to form a palisade-like structure. The possible origin and function of this structure is discussed.     

Predominantly cerebral manifestation in Urbach-Wiethe's syndrome (lipoid proteinosis cutis et mucosae): a clinical and pathomorphological study

The neurological and psychiatric manifestations in a case of Urbach-Wiethe's disease are reported. The present case is characterized by the predominance of cerebral symptoms: ataxia, psychomotoric seizures, paranoic hallucinatory psychosis and attacks of rage. At autopsy, deposits of amyloid-like material in the walls of the brain vessels could be observed. This finding, together with the mucocutaneous alterations, confirmed the diagnosis of the rare disease know as "lipoid proteinosis cutis et mucosae".     

The blepharo-periorbitoplasty: anatomical basis

A new combined subperiosteal-subcutaneous musculo-aponeurotic system and suborbicularis technique is described: the "blepharo-periorbitoplasty." This technique achieves complete mobilization of the forehead and brow, the lower eyelid, the raphe and lateral canthal area, the upper palpebral region, and of the suprazygomatic and infrazygomatic soft tissues, including the cheeks. These soft tissues are displaced upward and moderately backward. If a major lateral upward slant of the palpebral fissure is desired, Hinderer's lateral canthoplasty must be added. The blepharo-periorbitoplasty technique can be combined with a facial-cervical rhytidectomy. The technique is also useful for senile preectropion and postoperative "round eye" conditions with scleral show. The safety has been proven both clinically and in anatomical dissections.     

Tricuspid atresia. Clinical course in 120 children

We describe the clinical course of 120 children with tricuspid atresia (TA) attended in the Hospital de Cardiología y Neumología, "Dr. Luis Méndez", del Centro Médico Nacional. There were 61 males and 59 females. The age of presentation was in 79 newborn babies, seventeen between one and six months old, 20 between six and 24 months old, and four with two or more years old. The clinical picture was hypoxic spells in 89% and congestive heart failure in the others. The chest film showed cardiomegaly in 85%, with diminished pulmonary flow in 48%, increased flow in 27.5%, and normal in 9%. The electrocardiogram with superior left axis deviation in 94%, right atrial hypertrophy in 58%, left atrial hypertrophy in 47.5% and left ventricular hypertrophy in 96%. TA was classified as type I in 103 children, type Ic in 70, Ib in 27 and Ia in six, and type II in seventeen children, with eight IIc, six IIb and three IIa. In 44 the management was medical, 63 underwent systemic-pulmonary anastomosis, 37 of them with Blalock-Taussig shunt and Fontan procedure in thirteen children. There were 21 deaths. This survey is compared with the literature and from this point we make management recommendations.     

Amphetamine-clonidine interaction on neurotransmission in the vas deferens of the rat

The interaction between amphetamine and clonidine on neurotransmission in the rat vas deferens was studied. In the whole vas deferens, clonidine 0.037 mumol/l displaced to the right the frequency-response curve evoked by either hypogastric or field stimulation. The frequency of stimulation that produced 50% of the maximal response (EF 50) was: control 4.0 Hz, clonidine 18.3 Hz (P less than 0.001 n = 4), for hypogastric nerve stimulation; and 2.1 Hz in controls and 17.1 Hz in clonidine-treated preparations, for field stimulation (P less than 0.001 n = 5). Preincubation with 5.4 mumol/l amphetamine antagonized the effect of clonidine (EF 50 amphetamine alone 6.2 Hz, amphetamine + clonidine 7.3 Hz; P greater than 0.5). After 12 min of incubation with clonidine 0.037 mumol/l the responses to 6.4 Hz (3 s, 0.5 ms) were decreased by 77 +/- 2.2%. Both yohimbine and amphetamine, in a concentration-dependent manner, attenuated the inhibition. Washout of clonidine produced a slow recovery of the responses. Inhibition of the motor response to nerve stimulation (6.4 Hz, 3 s) by 30 mumol/l 2',3'-cAMP was increased by 10 mumol/l dipyridamole and impaired by 100 mumol/l theophylline. Amphetamine, in a concentration that markedly reduced clonidine inhibition of neurotransmission failed to antagonize 2',3'-cAMP. In the bisected vas deferens clonidine inhibited the peak motor response to short trains of field stimuli in the prostatic portion ("non-adrenergic") and the sustained response in the epididymal portion ("adrenergic"). Yohimbine potentiated both types of responses and fully prevented the effect of clonidine. In the prostatic portion amphetamine slightly inhibited the peak motor response and attenuated the inhibitory effect of clonidine in both portions of the vas.(ABSTRACT TRUNCATED AT 250 WORDS)     

A simple and safe technique for sterile autologous platelet labelling using “Monovette” vials

A simple technique of autologous platelet labelling is described, which allows labelling within 40 min, and has the advantage of low costs, as no laminar air flow is required. Blood (16 ml) was withdrawn into 4 ml ACD, 500 ng prostacyclin was added. After 10 min sedimentation the vials were centrifuged for 5 min at 150 g. The plateletrich plasma in the supernatant was centrifuged at 500 g for 10 min to obtain a platelet pellet. The platelet-poor plasma was preserved in a sterile syringe and the platelet pellet was resuspended in 1 ml tyrode buffer. The cell suspension was labelled at 37° C for 5 min with 100 Ci ¹¹¹In-oxine sulphate and reinjected after dilution with the plasma. Mean labelling efficiency was 90%±3%, mean recovery 2 h after reinjection 76%±3% (mean±SD).     

Amyotrophic cerebellar hypoplasia

Summary Lower motor neuron degeneration, cerebellar hypoplasia, atrophy of pons, olives, and cerebellum, sclerosis of thalamus and pallidum, and deficient myelination were found in a 2-months-old baby with laryngeal paralysis, mental retardation, progressive amyotrophy, and slow nerve conduction velocity. Such changes seem characteristic of an unusual syndrome previously referred to as cerebellar hypoplasia in Werdnig-Hoffmann disease, or anterior horn cell disease with pontocerebellar hypoplasia. Although the pathologic changes in lower motor neurons are indistinguishable from those in other cases of infantile spinal muscular atrophy, the consistent reproducibility of a complex pathologic pattern suggests that this is probably a manifestation of a separate disease process. The term amyotrophic cerebellar hypoplasia (ACH) is a convenient designation for the syndrome.Supported in part by National Institutes of Health grant no. RR75     

A possible paracellular route for the resolution of hydrocephalic edema

Summary Considering the possibility of a paracellular route for edema resolution we studied the microvasculature of the subependymal and subcortical white matter in hydrocephalic rats. Normal adult rats were used as controls. After injection of kaolin suspension into the cisterna magna, the animals were killed at intervals of 1, 2, 4, and 8 weeks. In hydrocephalic rats at 1 week after kaolin injection, widening of the interendothelical cleft between the tight junction (dehiscence) was seen in 27 of 76 (35%) vessels. At 2 weeks after kaolin injection, the number of the dehiscences had increased (39/7:56%) and some were enlarged, forming interendothelial blisters. At 4 weeks in hydrocephalic rats, both dehiscences and blisters were still prominent (45/7363%) and at 8 weeks the dehiscences were still prominent, but the number of the blisters had decreased (25/8131%). The blisters and dehiscences were most pronounced in the corpus callosum and occipital regions. Following i.v. injection of horseradish peroxidase, the interendothelial dehiscences and blisters were completely devoid of the marker substance. These findings indicate that in obstructive hydrocephalus the tight junctions may constitute part of a paracellular pathway for the resorption of interstitial edema fluid.     

Correction to: Longitudinal associations of physical fitness and affect with depression,anxiety and life satisfaction in adult women with fibromyalgia

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