The enzymes responsible for the posttranslational processing of precursor proteins to form alpha-amidated peptide hormones require the availability of several cofactors, including zinc, copper and ascorbate ions. Major changes in the availability of these cofactors, as well as the rate of hormone precursor conversion to active hormone, occur during neonatal development, aging and caloric restriction. The effects of 6 weeks of a zinc-deficient (ZD1) diet, pair feeding (PF) and partial zinc deficiency (ZD6) compared to a control diet on the enzymatic cleavage and processing of prepro-TRH to form TRH have been studied in the hypothalamus, brain, and pituitary of young adult male Sprague-Dawley rats. Reverse phase high pressure liquid chromatography (HPLC) revealed that TRH was the major TRH-IR component of the hypothalamus, brain and pituitary. The effect of zinc deficiency on the TRH-Gly-IR HPLC profile of rat brain was to reduce selectively the are of the peaks for TRH-Gly and other low molecular weight pro-TRH peptide fragments with a C-terminal Gly compared to the corresponding TRH-Gly-IR peaks of the control group. We conclude that the processing of prepro-TRH to form TRH is zinc dependent via posttranslational processing enzymes such as carboxypeptidase H.

Amino Acid Sequence↗

PubMedDate not supplied

Testosterone increases TRH biosynthesis in epididymis but not heart of zinc-deficient rats.

Enzymes responsible for the posttranslational processing of precursor proteins to form alpha-amidated peptide hormones require the availability of several cofactors, including zinc, copper, and ascorbic acid. For this reason, we studied the effects of 6 weeks of a zinc-deficient diet (ZD1; 1 microgram zinc per g diet), pair-feeding (PF), and marginal zinc deficiency (ZD6; 6 micrograms zinc per g diet) compared to a control diet (36 micrograms/g zinc) on the conversion of prepro-TRH to TRH in epididymides, testes, prostate, pancreas, and heart of young adult, male Sprague-Dawley rats. In the epididymis, severe zinc deficiency (ZD1 diet) reduced TRH and TRH-like peptides to undetectable levels. In ZD6 animals, TRH was selectively inhibited 80%, while pair-feeding increased all of these peptide levels compared to controls. A similar effect of zinc deficiency on the TRH precursor peptides was observed. A quantitative loss of TRH from the testes of ZD1 was also observed. Zinc deficiency results in a substantial reduction in body weight and testosterone production in male rats. Exogenous testosterone (T) supplementation of ZD1 rats resulted in a selective increase in the TRH concentration of the epididymis but not of the heart. The change in steady-state levels of TRH precursor peptides in the hearts of the ZD1+T rats was consistent with a reduction in the activity of the zinc-dependent carboxypeptidase H enzyme. We conclude that severe zinc deficiency inhibits TRH biosynthesis in reproductive tissues of the male rat due to the combined effects of hypogonadism and inhibition of the zinc-dependent carboxypeptidase H.

Amino Acid Sequence↗

PubMedDate not supplied

Automatic ventricular edge detection for determination of left ventricular volumes, ejection fraction and regional ejection fractions from first pass radioisotope angiography.

An automated method for detection of left ventricular (LV) outline (including the aortic and mitral valve planes) was developed for measurements of end-diastolic volume (EDV), end-systolic volume (ESV), global ejection fraction (EF), and regional EFs from first pass radioisotope ventriculography. The procedure includes: (1) interpolative background subtraction, (2) construction of gradient images, (3) automatic detection of valve planes, and (4) automatic radial search of LV outlines. The correlation between contrast angiography and Tc-99m first pass study was r = 0.84 (SEE = 23.4) for EDV, r = 0.93 (SEE = 12.8) for ESV, r = 0.84 (SEE = 6.91) for EF (via counts) and r = 0.80 (SEE = 8.56) for EF (via area-length method). Tests of intra-observer, inter-observer and inter-study variability revealed low level of variability. The results showed the potential of the automation of data processing for first pass radioisotope ventriculography.

Cardiac Volume↗

PubMedDate not supplied

Computerized localization of brain structures in single photon emission computed tomography using a proportional anatomical stereotactic atlas.

An accurate identification of cerebral structures is necessary to perform quantification of single photon emission computed tomography (SPECT). We have developed an anatomical localization system that accounts for individual brain shapes and sizes by using the Talairach proportional grid system. The locations of the commissural lines, which define the stereotactic coordinate system, are calculated from the external landmarks provided by the canthomeatal line. This is validated on MRI images. When applied to SPECT data, the use of a neuroanatomical atlas data along with the automaticity of the processing guarantees a high degree of objectivity and inter-observer reproducibility.

Anatomy, Artistic↗

PubMedDate not supplied

Enhanced artistic creativity with temporal lobe degeneration.

Explore the source record for details and available documents.

Art↗

PubMedDate not supplied

Testing the count rate performance of the scintillation camera by exponential attenuation: decaying source; multiple filters.

An algorithm and two FORTRAN programs have been developed to evaluate the count rate performance of scintillation cameras from count rates reduced exponentially, either by a decaying source or by filtration. The first method is used with short-lived radionuclides such as 191mIr or 191mAu. The second implements a National Electrical Manufacturers' Association (NEMA) protocol in which the count rate from a source of 191mTc is attenuated by a varying number of copper filters stacked over it. The count rate at each data point is corrected for deadtime loss after assigning an arbitrary deadtime (tau). A second-order polynomial equation is fitted to the logarithms of net count rate values: ln(R) = A + BT + CT2 where R is the net corrected count rate (cps), and T is the elapsed time (or the filter thickness in the NEMA method). Depending on C, tau is incremented or decremented iteratively, and the count rate corrections and curve fittings are repeated until C approaches zero, indicating a correct value of the deadtime (tau). The program then plots the measured count rate versus the corrected count rate values.

Algorithms↗

PubMedDate not supplied

Neuronal ultrastructural abnormalities in a patient with frontotemporal dementia and motor neuron disease.

Motor neuron disease (MND) can be associated with frontotemporal dementia (FTD) and circumscribed lobar atrophy of frontal and temporal lobes. Neuropathological correlations were sought in postmortem studies from a woman with these associated conditions. Cerebral blood flow imaging and autopsy showed cortical abnormalities in the frontal and temporal lobes, but typical argyrophilic Pick's bodies were absent and ubiquitin-positive neuronal cytoplasmic inclusions were rare. However, hematoxylin and eosin staining revealed eosinophilic, granular, central cytoplasmic 'clearing' in most neurons of the substantia nigra and in cervical anterior horn cells. Electron microscopy showed that these neurons contained a central cytoplasmic zone cleared of neuromelanin and normal cytoplasmic organelles containing small mitochondria with matrix inclusions and randomly oriented filamentous material. A mitochondrial dysfunction or defective transport of mitochondria into axonal processes needs to be studied as a potential cause for the coassociation of MND and FTD.

Atrophy↗

PubMedDate not supplied

Dietary changes, compulsions and sexual behavior in frontotemporal degeneration.

The occurrence of weight gain, sweet and carbohydrate craving, hyposexuality, and compulsions in frontal lobe dementia (FLD) compared to Alzheimer's disease (AD) was evaluated. FLD is a progressive dementia with a high rate of misdiagnosis and therefore better diagnostic criteria for FLD are needed. Fourteen patients meeting research criteria for AD were compared to 14 with suspected FLD. All had cerebral perfusion measured with xenon-133 and imaged with HMPAO using brain-dedicated SPECT. The FLD group showed frontotemporal and AD posterior temporoparietal hypoperfusion. The primary caregivers were queried regarding weight gain, sweet/carbohydrate preference, sexual drive, and compulsions. Differences were compared with Fisher's exact test. The following was found in FLD versus AD: Weight gain in FLD patients amounted to 64% (AD 7%), carbohydrate craving was 79% (vs. 0%) and compulsive behavior 64% (vs. 14%). The differences for these symptoms were statistically significant, whereas for the symptoms increased sexual drive (8 vs. 8%) and reduced sexual drive (54 vs. 23%) no significant difference could be found. In FLD the first symptoms were often dietary changes or hyposexuality. Compulsions were more bizarre and severely disabling in FLD than in AD. Dietary changes, hyposexuality, and disabling compulsions are prominent early symptoms in FLD but not AD. The cause of these symptoms may be due to both frontal and subcortical serotonin loss and dysfunction of the anterior temporal lobes.

Alzheimer Disease↗

PubMedDate not supplied

Progressive right frontotemporal degeneration: clinical, neuropsychological and SPECT characteristics.

The behavioral, neuropsychological and single photon emission computerized tomography characteristics of 5 patients with progressive degeneration of the right hemisphere are described. In all, the brain regions with greatest involvement were right-frontal and temporal. Psychosis, compulsions and behavioral disinhibition were the dominant, and often first, symptoms. Affect was flattened and the patients seemed distant and remote. Neuropsychological testing did not reveal a consistent pattern that helped localize the abnormality to the right frontotemporal region. These patients contrast dramatically to those with left frontotemporal degeneration in whom behavior and psychiatric status is often normal. This study suggests that the right hemisphere may be primary for the control of social conduct.

Aged↗