Stress-first single photon emission computed myocardial perfusion imaging

BACKGROUND

Myocardial perfusion imaging (MPI) with single photon emission tomography (SPET) is widely used in coronary artery disease evaluation. Recently major dosimetric concerns have arisen. The aim of this study was to evaluate if a pre-test scoring system could predict the results of stress SPET MPI, thus avoiding two radionuclide injections.

METHODS

All consecutive patients (n=309) undergoing SPET MPI during the first 6 months of 2014 constituted the study group. The scoring system is based on these characteristics: age >65 years (1 point), diabetes (2 points), typical chest pain (2 points), congestive heart failure (3 points), abnormal ECG (4 points), male gender (4 points), and documented previous CAD (5 points). The patients were divided on the basis of the prediction score into 3 classes of risk for an abnormal stress-first protocol.

RESULTS

An abnormal stress SPET MPI was present in 7/31 patients (23%) with a low risk score, in 24/90 (27%) with an intermediate score risk, and in 124/188 (66%) with an high score risk. ROC curve analysis showed good prediction of abnormal stress MPI.

CONCLUSIONS

Our results suggest an appropriate use of a pre-test clinical prediction formula of abnormal stress MPI in a routine clinical setting.

Activated c-Kit receptor in the heart promotes cardiac repair and regeneration after injury

The role of endogenous c-Kit receptor activation on cardiac cell homeostasis and repair remains largely unexplored. Transgenic mice carrying an activating point mutation (TgD814Y) in the kinase domain of the c-Kit gene were generated. c-Kit^TgD814Y receptor was expressed in the heart during embryonic development and postnatal life, in a similar timing and expression pattern to that of the endogenous gene, but not in the hematopoietic compartment allowing the study of a cardiac-specific phenotype. c-Kit^TgD814Y mutation produced a constitutive active c-Kit receptor in cardiac tissue and cells from transgenic mice as demonstrated by the increased phosphorylation of ERK1/2 and AKT, which are the main downstream molecular effectors of c-Kit receptor signaling. In adult transgenic hearts, cardiac morphology, size and total c-Kit⁺ cardiac cell number was not different compared with wt mice. However, when c-Kit^TgD814Y mice were subjected to transmural necrotic heart damage by cryoinjury (CI), all transgenic survived, compared with half of wt mice. In the sub-acute phase after CI, transgenic and wt mice showed similar heart damage. However, 9 days after CI, transgenic mice exhibited an increased number of c-Kit⁺CD31⁺ endothelial progenitor cells surrounding the necrotic area. At later follow-up, a consistent reduction of fibrotic area, increased capillary density and increased cardiomyocyte replenishment rate (as established by BrdU incorporation) were observed in transgenic compared with wt mice. Consistently, CD45⁻c-Kit⁺ cardiac stem cells isolated from transgenic c-Kit^TgD814Y mice showed an enhanced endothelial and cardiomyocyte differentiation potential compared with cells isolated from the wt. Constitutive activation of c-Kit receptor in mice is associated with an increased cardiac myogenic and vasculogenic reparative potential after injury, with a significant improvement of survival.

Looking for Calcium Phosphate Composite Suitable to Study Osteoclast Endocytosis: Preliminary Observations

One of the issues regarding in vitro study of bone resorption is the synthesis of a bone-like biomaterial forming a thin layer onto either glass or plastic. The synthesis of a bone-like material suitable for in vitro studies can be valuable both to investigate osteoclast differentiation, that in vivo proceeds within the local microenvironment of bone and to understand how its presence triggers activation of macrophages present in situ when bone is damaged (a scenario that can occur for example in case of bone fracture). Despite the intensive studies committed to recreate synthetic bone analogues, the most used substrates for in vitro studies on bone resorption are slices of bone or dentine. Therefore morphological investigations (i.e. fluorescence analysis and phase contrast) are strongly compromised due to the thickness of the bone analogue. In the present study, with the aim to guarantee a versatile (and easy to be made) substrate, that could be suitable to study cell adhesion and morphology by epifluorescence, phase contrast and TEM, we developed a biomaterial containing a calcium phosphate salt and type I collagen. This material (made specifically for in vitro studies) forms a very thin layer that allowed to merge the morphological information derived from phase-contrast and epifluorescence observation, making possible the observation of the interface between cell and matrix. Moreover the electron microscopy evaluation of the endocytosis performed on cell differentiated could be more suitable because sample does not need the process of demineralization.

Complementary therapy in polycystic ovary syndrome

Polycystic Ovary Syndrome (PCOS) is an endocrine disease. PCOS afflicts 5 to 10 % of women of reproductive age. The symptoms are: amenorrhea, oligomenorrhea, hirsutism, obesity, infertility, chronic hyperandrogenic anovulation and acne.

OTHER RISK FACTORS AGGRAVATE THIS CONDITION

insulin resistance, obesity, hypertension, dyslipidemia, inflammation and subclinical cardiovascular disease. Anxiety, depression and reduced quality of life are also common. This review highlights the mechanisms and the beneficial effects of acupuncture, exercise and resveratrol on animal models and on humans affected by PCOS.

AD-linked, toxic NH2 human tau affects the quality control of mitochondria in neurons

Functional as well as structural alterations in mitochondria size, shape and distribution are precipitating, early events in progression of Alzheimer's Disease (AD). We reported that a 20-22kDa NH2-tau fragment (aka NH2htau), mapping between 26 and 230 amino acids of the longest human tau isoform, is detected in cellular and animal AD models and is neurotoxic in hippocampal neurons. The NH2htau -but not the physiological full-length protein- interacts with Aβ at human AD synapses and cooperates with it in inhibiting the mitochondrial ANT-1-dependent ADP/ATP exchange. Here we show that the NH2htau also adversely affects the interplay between the mitochondria dynamics and their selective autophagic clearance. Fragmentation and perinuclear mislocalization of mitochondria with smaller size and density are early found in dying NH2htau-expressing neurons. The specific effect of NH2htau on quality control of mitochondria is accompanied by (i) net reduction in their mass in correlation with a general Parkin-mediated remodeling of membrane proteome; (ii) their extensive association with LC3 and LAMP1 autophagic markers; (iii) bioenergetic deficits and (iv) in vitro synaptic pathology. These results suggest that NH2htau can compromise the mitochondrial biology thereby contributing to AD synaptic deficits not only by ANT-1 inactivation but also, indirectly, by impairing the quality control mechanism of these organelles.

Inhibition of bone resorption by Tanshinone VI isolated from Salvia miltiorrhiza Bunge

During the last decade, a more detailed knowledge of molecular mechanisms involved in osteoclastogenesis has driven research efforts in the development and screening of compound libraries of several small molecules that specifically inhibit the pathway involved in the commitment of the osteoclast precursor cells. Natural compounds that suppress osteoclast differentiation may have therapeutic value in treating osteoporosis and other bone erosive diseases such as rheumatoid arthritis or metastasis associated with bone loss. In ongoing investigation into anti-osteoporotic compounds from natural products we have analyzed the effect of Tanshinone VI on osteoclasts differentiation, using a physiologic three-dimensional osteoblast/bone marrow model of cell co-culture. Tanshinone VI is an abietane diterpene extracted from the root of Salvia miltiorrhiza Bunge (Labiatae), a Chinese traditional crude drug, “Tan-Shen”. Tashinone has been widely used in clinical practice for the prevention of cardiac diseases, arthritis and other inflammation-related disorders based on its pharmacological actions in multiple tissues. Although Tanshinone VI A has been used as a medicinal agent in the treatment of many diseases, its role in osteoclast-related bone diseases remains unknown. We showed previously that Tanshinone VI greatly inhibits osteoclast differentiation and suppresses bone resorption through disruption of the actin ring; subsequently, we intended to examine the precise inhibitory mechanism of Tanshinone VI on osteoclast differentiating factor. This study shows, for the first time, that Tanshinone VI prevents osteoclast differentiation by inhibiting RANKL expression and NFkB induction.

Methylated tin toxicity a reappraisal using rodents models

Trimethyltin-induced intoxication has a great impact on human health due to the widespread occurrence of methyltin compounds. Acute TMT intoxication in humans leads to a variety of neurological symptoms which involve primarily the limbic system. In the present review we summarized the neuromorphological correlates of this neurological syndrome extending the analysis to various extra-limbic regions and detailing the fine ultrastructure of TMT-induced neuronal alterations. In order to comprehend the pathophysiology of TMT-induced neuronal damage we analysed the various experimental models of TMT-induced neurotoxicity. When comparing various animal species, it seems that the variety of neuropathological correlates are not related to species difference in the sensitivity to TMT toxicity but to a different susceptibility to secondary effects produced by TMT. In fact, apart from a primary neurotoxic damage induced by TMT at neuronal level, this compound promotes the onset of limbic and generalized seizures, which in turn add a secondary damage to that induced immediately by TMT. Thus, the different neuropathology observed in different animal species is produced mainly by a different sensitivity to epilepsy-induced brain damage.

Methamphetamine induces ectopic expression of tyrosine hydroxylase and increases noradrenaline levels within the cerebellar cortex

Methamphetamine produces locomotor activation and typical stereotyped motor patterns, which are commonly related with increased catecholamine activity within the basal ganglia, including the dorsal and ventral striatum. Since the cerebellum is critical for movement control, and for learning of motor patterns, we hypothesized that cerebellar catecholamines might be a target of methamphetamine. To test this experimental hypothesis we injected methamphetamine into C57 Black mice at the doses of 5 mg/kg two or three times, 2 h apart. This dosing regimen is known to be toxic for striatal dopamine terminals. However, we found that in the cerebellum, methamphetamine increased the expression of the primary transcript of the tyrosine hydroxylase (TH) gene, followed by an increased expression of the TH protein. Increased TH was localized within Purkinje cells, where methamphetamine increased the number of TH-immunogold particles, and produced a change in the distribution of the enzyme by increasing the cytoplasmic percentage. Increased TH expression was accompanied by a slight increase in noradrenaline content. This effect was highly site-specific for the cortex of posterior vermal lobules, while only slight effects were detectable in the hemispheres. The present data indicate that the cerebellum does represent a target of methamphetamine, which produces specific and fine alterations of the catecholamine system involving synthesis, amount, and compartmentalization of TH as well as increased noradrenaline levels. This may be relevant for motor alterations induced by methamphetamine. In line with this, inherited cerebellar movement disorders in various animal species including humans are associated with increased TH immunoreactivity within intrinsic neurons of the same lobules of the cerebellar cortex.

Ultrastructural characterization of calcification onset and progression in subdermally implanted aortic valves. Histochemical and spectrometric data

Detailed characterization of the subdermal model is a significant tool for better understanding of calcification mechanisms occurring in heart valves. In previous ultrastructural investigation on six-week-implantated aortic valve leaflets, modified pre-embedding glutaraldehyde-cuprolinic-blue reactions (GA-CB) enabled sample decalcification with concurrent retention/staining of lipid-containing polyanionic material, which lined cells and cell-derived matrix-vesicle-like bodies (phthalocyanin-positive layers: PPLs) co-localizing with the earliest apatite nucleation sites. Additional post-embedding silver staining (GA-CB-S) revealed PPLs to contain calcium-binding sites. This investigation concerns valve leaflets subjected to shorter implantation times to shed light on the modifications associated with PPLs generation and calcification onset/progression. Spectrometric estimations revealed time-dependent calcium increase, for unreacted samples, and copper modifications indicating an increase in acidic, non-glycanic material, for GA-CB-reacted samples. Two-day-implant thin sections showed emission and subsequent reabsorption of lamellipodium-like protrusions by cells, originating ECM-containing vacuoles, and/or degeneration stages characterized by the appearance of GA-CB-S-reactive, organule-derived dense bodies and progressive dissolution of all cell membranes. In one-week-implants, the first PPL-lined cells were found to co-exist with cells where GA-CB-S-reactive material accumulated, or exudated towards their edges, or outcropped at the ECM milieu, so acquiring PPL features. PPL-derived material was observed increasingly to affect the ECM on thin sections of one-week- to six-week-implants. These results show an endogenous source for PPLs and reveal that a peculiar cascade of cell degenerative steps is associated with valve mineralization in the subdermal model, providing new useful parameters for more reliable comparison of this experimental calcification process versus the physiological and pathological processes.

Malachite green and phthalocyanine-silver reactions reveal acidic phospholipid involvement in calcification of porcine aortic valves in rat subdermal model

Subdermal implant models are helpful in the study of calcification "in vivo" and for testing anticalcific treatments. After implantation of porcine aortic valve leaflets in rat subcutis, we previously found that glutaraldehyde-Cuprolinic blue reactions (GA-CB) at low pH induce favourable tissue unmasking from mineral deposits, and visualize peculiar, electrondense layers that outline the calcifying cells and matrix vesicle-like structures. The layer-forming material seemed to consist of acidic phospholipids because of its anionic nature and differential susceptibility to chemical/enzymatic extractivity. In the present investigation, pre-embedding glutaraldehyde-Malachite green (GA-MG) reactions and subsequent osmium post-fixation were compared with pre-embedding GA-CB reactions, combined with post-embedding von Kossa silver staining (GA-CB-S), to assess whether the layer-forming material is actually composed of acidic phospholipids and exhibits calcium-binding properties. After lowering standard pH, GA-MG reactions also caused sample demineralization and the appearance of pericellular osmium-MG-reactive layers comparable to CB-reactive ones. Moreover, GA-CB-S reactions showed that major silver precipitation was superimposed to the CB-reactive layers, whereas minor metal extra-precipitation occurred at three distinct, additional sites. These results demonstrate that a unique process of cell degeneration occurs in this calcification model, in which acidic phospholipids accumulate at cell surface, replacing cell membrane and acting as major apatite nucleator. However, the overall observations are consistent with the hypothesis that certain phases are common to the various types of normal and/or abnormal calcification.

Altered balance of proteinase inhibitors in atrophic muscle after denervation

Skeletal muscle denervation leads to an increase of proteolytic activity, which is also favoured by reduced levels of alpha1 antichymotrypsin and nexin II, two serine-proteinase inhibitors normally acting at the neuromuscular junction. In the present experiments we extended our investigation to other muscular proteinase inhibitors after denervation. In all muscles examined (soleus, plantaris, extensor digitorum longus) specific immunoreactivity for alpha2macroglobulin (alpha2M) and alpha1proteinase inhibitor (alpha-1-antitrypsin, ATI) was distributed in peri-endomysial structures as well as in small patches inside the fibres. By contrast, inter-alpha-trypsin inhibitor (ITI) was mainly localized in the extracellular matrix. These localization patterns did not change substantially in 15-days denervated muscles. Dot-blot analysis revealed a small decrease (about 15%) of alpha2M in 15-days denervated muscles, while ATI and ITI specific activities were substantially unchanged. RT-PCR allowed us to detect the above protease inhibitor mRNAs in normal muscle homogenates. Denervation atrophy induced by section of the sciatic nerve resulted in a remarkable reduction of (2macroglobulin mRNA (60%) and ITI (30%), but not ATI, as measured by computer-assisted semiquantitative densitometry of electrophoresed RT-PCR bands. The marked decrease of alpha2M we have detected in denervated muscle may be responsible, at least in part, for the proteolytic increase which is known to occur in skeletal muscle during denervation atrophy.

Immunohistochemical detection of three serum protease inhibitors in mouse skeletal muscle by confocal laser scanning microscopy

The tissue-associated counterpart of some plasmatic protease inhibitors has been studied in mouse skeletal muscle by combining immunoperoxidase confocal microscopy and Western blot analysis. To remove serum contamination all experiments were performed on C57 BL/10 adult mice perfused extensively with physiological solution under deep anesthesia. The following serum inhibitors were investigated in skeletal muscle by immunoperoxidase staining: alpha-2-macroglobulin (alpha2M), antithrombin III (ATIII) and inter-alpha-trypsin inhibitor (ITI). The resulting localization patterns were analysed by laser transmittance scanning at 488 nm using a confocal microscope. Images obtained from a series of optical sections were then digitally intensified by a computerized program, allowing detection of even negligible amounts of immunoreaction product. In all muscles examined (soleus and extensor digitorum longus mm.) an extracellular (endomysial) localization was apparent for all inhibitors. By contrast remarkable differences were observed for the intracellular component: in fact alpha2M was present in about a half of the muscle fibers; ATIII was present inside all fibers; intracellular ITI was completely absent. Western blotting analysis of muscle homogenate was performed to biochemically characterize the above immunoreactivities. In preliminary experiments alpha2M-related immunoreactivity could not be found in the soluble fraction of perfused muscle, confirming an absence of serum contamination after in vivo perfusion. By contrast experiments on detergent-solubilized extracts (0.3% Triton X-100) revealed that tissue-bound alpha2M consisted of two main bands (168-166 KDa) and a minor component (35 KDa); ATIII of a single band (50 KDA); ITI of four bands (180, 50, 45, 40 KDa). These results confirmed that the specific immunoreactivities visualized by morphological techniques corresponded to muscle-associated plasmatic inhibitors. The present data suggest that in mouse skeletal muscle i) numerous tissue-associated plasmatic inhibitors may protect the extracellular matrix from an excess of proteolysis; ii) a more restricted set of inhibitors may be also involved in the down-regulation of intracellular proteolytic processes.

Effect of skeletonization of the internal thoracic artery on vessel wall integrity

BACKGROUND

This study was conceived to evaluate the effect of internal thoracic artery (ITA) skeletonization on vessel wall integrity.

METHODS

Forty consecutive patients undergoing coronary artery bypass were randomized to receive a skeletonized (n = 22) or a pedicled (n = 18) ITA graft. ITA harvesting was performed by 2 experienced surgeons using the same instrumentation and technique. Specimens were examined by light and electron microscope in order to assess vascular wall integrity. A specific immunohistochemical staining and a computerized method were used to quantify the degree of endothelial integrity after surgical preparation.

RESULTS

Morphologic analysis revealed 2 cases of limited subadventitial hemorrhage (one for each group) and no case of major arterial damage. Immunohistochemical staining demonstrated an extremely high degree of maintenance of the endothelial integrity in both groups (97.2% +/- 1.9% in the skeletonized and 96.8% +/- 2.1% in the pedicled one; p = 0.53).

CONCLUSIONS

Skeletonization does not affect ITA wall integrity in humans submitted to coronary artery bypass procedures.

Sensitivity of human melanoma cells to oestrogens, tamoxifen and quercetin: is there any relationship with type I and II oestrogen binding site expression?

We investigated the effect of oestrogens, anti-oestrogens and flavonoids on the growth of a human melanoma cell line (SK-Mel-28) and, at the same time, the presence of both type I oestrogen receptors (ERs) and type II oestrogen binding sites (type II EBS) to gain a fuller picture of the relationship between melanoma cell proliferation and receptor status. 17beta-Oestradiol (E2) and the flavonoid quercetin (Q) produced a marked inhibition of proliferation, but only at the highest dose used (10(-5) M) and only when added daily to the medium. Diethylstilboestrol (DES) (10(-5) M) was effective in inhibiting cell growth when the medium was renewed every 3 days and produced a more pronounced reduction when added daily to the medium. Tamoxifen (TAM) inhibited cell proliferation at a dose starting from 10(-7) M when the medium was renewed every 3 days. When added daily to the medium, it did not induce a greater inhibitory effect and it was cytotoxic at 5 x 10(-6) M and 10(-5) M. The antiproliferative effect of E2, DES and Q did not seem to be dependent on their interaction with ERs, which were minimally detected in SK-Mel-28 in both immunocytochemical and biochemical assays. Our model revealed, through a biochemical assay, a large number of type II EBSs which could be involved in the anti-oestrogen action, but this does not exclude the involvement of other mechanisms. Finally, TAM (10(-5) M) appeared to reduce the activity of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase, an effect that could be interesting from the point of view of the therapeutic efficacy of alkylating agents.

Pharmacological and histochemical evidence for P2X receptors in human umbilical vessels

The presence of P2X purinoceptors in human umbilical vessels were studied with organ bath recording, radioligand binding assays, autoradiography, and immunohistochemistry. In isolated umbilical arteries and veins from normal term pregnancy, both ATP and alpha,beta-methylene ATP caused concentration-dependent contractions. ATP-induced responses were blocked by desensitisation with alpha,betamethylene ATP. However, both the ATP- and alpha,beta-methylene ATP-induced responses were not antagonised by suramin. No significant difference in responses was observed in the vessels with or without endothelial cells. Radioligand binding assays using [3H]alpha,beta-methylene ATP showed the presence of a population of high-affinity binding sites in both the arteries and veins. The Kd values of the binding sites were 2.77 + 1.10 nM for the arteries, and 3.23+/-1.22 nM for the veins. The maximum binding site densities were 634+/-237 and 947+/-308 fmol/mg protein for the arteries and the veins, respectively. Autoradiographic localisation with [3H]alpha,beta-methylene ATP demonstrated that the specific binding sites were only distributed over the smooth muscle cells of the vessels. Immunohistochemical studies with specific polyclonal antibodies against P2X1-6 receptors showed that positive immunostaining was also restricted to smooth muscle cells. Antibodies against P2X1 receptors produced the strongest signals, while antibodies against the other five P2X subtypes produced much weaker signals. The results in the present study indicate the existence of P2X purinoceptors in the smooth muscle of human umbilical vessels. Their physiological functions remain to be studied.

P2X purinoceptors in postmortem human cerebral arteries

Pharmacological studies have demonstrated that various purinoceptors are involved in the control of the cerebral vascular tone in many species. In this study, the existence of P2X purinoceptors in the postmortem human cerebral arteries was investigated with organ-bath pharmacology, autoradiography, and immunohistochemistry. Specimens were obtained from the M2 region of the middle cerebral arteries from human cadavers with an age range of 53-91 years and postmortem time of 37-54 h. Application of alpha,beta-methylene adenosine triphosphate (ATP) produced concentration-dependent contraction in the arterial ring, whereas transmural nerve stimulation and noradrenaline did not elicit contraction. Autoradiography using [3H]alpha,beta-methylene ATP (a radioligand for P2X purinoceptors) showed specific [3H]alpha,beta-methylene ATP binding sites in the smooth-muscle cells of the postmortem human cerebral arteries. Immunohistochemistry with specific P2X1 purinoceptor antibodies revealed positive staining exclusively in the smooth muscle of the same specimens. All these results demonstrate the existence of P2X purinoceptors in human cerebral arteries, which were still functionally active despite the long postmortem time. The results from this study suggest that the postmortem human cerebral arteries can be useful specimens for studying the P2X purinoceptor-mediated responses.

Protease inhibitors in mouse skeletal muscle: tissue-associated components of serum inhibitors and calpastatin

The proteinase inhibitor set in skeletal muscle is poorly characterized at present. This study was aimed to investigate in mouse skeletal muscle 1) the tissue-associated counterpart, if any, of serum protease inhibitors (which may also play antiproteolytic functions in tissues) and 2) calpastatin, a tissue inhibitor of calcium-activated neutral proteases (calpains). Triton-extracts were prepared from muscle homogenates of mice, which had been perfused extensively with phosphate buffered saline (PBS) (under deep anesthesia) to remove blood inhibitors. Among various inhibitors tested, the following muscle-associated inhibitors were identified by western-blotting: alpha-2-macroglobulin (185, 165, 35 kDa), alpha-1-antitrypsin (52 kDa), inter-alpha-trypsin inhibitor (220, 180 kDa) and calpastatin (70 kDa). Combined light microscope and confocal immunohistochemical experiments revealed that, in all muscles examined (soleus, plantaris, extensor digitorum longus) the above specific immunoreactivities were localized outside the muscle fibers (in periendomysium, blood vessel wall) as well as within them. Inter-alpha-trypsin inhibitor, however, completely lacked the intracellular localization. This wide distribution of proteinase inhibitors suggests that numerous muscular structures may be normally protected from unwanted proteolysis, thus providing an essential background for further studies on pathological models with altered proteolysis (m. dystrophy, denervation atrophy, etc.).

Evidence for tissue-associated alpha(2) macroglobulin in mouse skeletal muscle

Alpha(2)-Macroglobulin (alpha(2)M), a major serum protease inhibitor, was localized in mouse skeletal muscle by immunoperoxidase histochemistry. In all muscles examined (mm. soleus, plantaris, and extensor digitorum longus) specific immunoreactivity occurred diffusely in extracellular structures (periendomysium, blood vessel wall) as well as inside about a half of the muscle fibers. This localization pattern did not change substantially by extensively perfusing deeply anesthetized mice with phosphate buffered saline (PBS) to remove serum alpha(2)M. In release experiments on fresh (nonfixed) cryostat sections, specific immunoreactivity persisted after an extensive prewash with PBS (up to 5-6 h), but a new specific staining appeared inside those fibers that were originally negative. Western blotting experiments were negative on the soluble fraction of muscle homogenate, thus confirming that the perfusion procedure was effective in removing serum alpha(2)M. By contrast, three specific bands (185, 165, and 35 kDa) appeared in detergent-solubilized extracts (0.3% Triton X-100), indicating the occurrence of tissue-associated alpha(2)M. Confocal immunofluorescence microscopy revealed that the intracellular specific staining was associated to a longitudinal network, probably corresponding to the sarcoplasmic reticulum. A multifunctional role of alpha(2)M in skeletal muscle was hypothesized.

Sensory Guillain-Barré syndrome

This report describes a clinical syndrome of a sensory variant of Guillain-Barré syndrome (GBS). A patient presented at our medical center with symptoms that began two weeks after she had had a normal childbirth. Symptoms included acute, rapidly progressive, and symmetrical sensory loss; areflexia; and mild nonprogressive weakness. Nerve conduction studies done at the time of her admission showed late response abnormalities consistent with GBS. Follow-up studies one week later were consistent with a predominantly sensory neuropathy with minimal motor deficits. Within a few months, both her sensory symptoms and motor weakness had markedly improved. Except for the predominance of sensory rather than motor deficits, these findings are consistent with those of GBS. The case for a sensory variant of GBS is further supported by autopsy findings as described by Dawson and associates.

Immunohistochemical evidence for sympathetic denervation and reinnervation after necrotic injury in rat myocardium

To study the short and long term effects of myocardial injury on sympathetic nerve fibers, a necrotizing lesion was performed on the diaphragmatic side of rat myocardium by freeze-thawing. Animals were sacrificed at 2, 6, 18, 28 and 105 days after the surgical procedure and paraffin-embedded hearts were subjected to peroxidase immunohistochemistry. According to previous studies cardiac nerves were visualized by staining their surrounding Schwann cells with an anti-S100 protein antibody. Catecholaminergic axons were specifically identified by an anti-tyrosine hydroxylase antibody. No S-100 positive structures were found in 2-day lesions (denervation). Starting from day 6,S-100 positive structures became progressively more evident (reinnervation) and persisted up to day 105. Many of these newly formed nerve fibers were positive for tyrosine hydroxylase, indicating that a necrotic injury of rat myocardium causes a disappearance of sympathetic innervation which is followed by a phase of sympathetic reinnervation.

Immunogold ultrastructural localization of calpastatin, the calpain inhibitor, in rabbit skeletal muscle

The ultrastructural localization of calpastatin, the endogenous inhibitor of the neutral calcium-dependent proteases (calpains), was investigated in rabbit skeletal muscle fibers using a polyclonal antibody against the 34 kDa form of the inhibitor isolated from rabbit. Quantitative studies by pre- and postembedding immunogold techniques revealed that the distribution pattern of the specific immunoreactivity included: 1) the sarcolemma with the adjacent cytoplasm (about 1 micron wide); 2) the myofibrils; 3) the mitochondria and 4) the nuclei (condensed as well as extended chromatin). Other cell substructures, such as lysosomes and the intermyofibrillar cytoplasm, were substantially devoid of immunoreactivity. Furthermore, in accordance to previous light microscope immunohistochemical experiments, an extracellular (endomysial) localization of specific immunoreactivity was confirmed. These results favour the view, which is also supported by a series of biochemical evidences, that calpastatin in rabbit skeletal muscle is present in cell structures also containing calpains and/or their putative substrates. The above multiple patterns of distribution also suggest that the muscular calpain-calpastatin system in skeletal muscle fibers may play different physiological roles in the various subcellular compartments.

Receptor-mediated endocytosis of alpha 2 macroglobulin by a glioma cell line

Previous experiments have shown that human neoplastic and embryonic glial cell lines synthesize and secrete in culture, alpha 2 macroglobulin (alpha 2M), a broad spectrum proteinase inhibitor present in serum and extracellular fluids. The present study was aimed to investigate the presence of alpha 2M receptors on glial cell membrane, since several non-neural cell types producing alpha 2M also express alpha 2M receptors. By flow cytometric analysis, immunofluorescence and immunoelectronmicroscopy techniques we demonstrate an alpha 2M receptor-related immunoreactivity on the plasma membrane of a human glioma cell line. Ultrastructural experiments reveal a close colocalization of immunoreactivities for alpha 2M and its receptor in clathrin-coated pits and vesicles, structures typically involved in receptor-mediated endocytic pathways.

Bovine pancreatic trypsin inhibitor and homologous polypeptide inhibitors in nephron cells

Bovine pancreatic trypsin inhibitor (BPTI, aprotinin) is a fifty-eight amino acid polypeptide, which is present together with related molecular isoforms in various bovine organs. In the present study these protease inhibitors were isolated from bovine kidney by affinity chromatography on immobilized trypsin and a subsequent FPLC step. Due to their electrophoretic, structural, and inhibitory properties, the inhibitors were strictly similar to the polypeptides identified previously in other bovine organs. Immunohistochemical experiments showed a widespread localization of these polypeptides in nephron epithelial cells (proximal and distal tubules, loop of Henle, collecting tubules).