[Giardiasis with malabsorption syndrome: report of one case]

A 10-year-old mentally retarded girl was sent to our hospital due to generalized edema, vomiting and poor appetite for several days. Serum albumin level was low, but no proteinuria was detected. Her stool was bulky and foul. Stool examination for parasite with formalin-ether concentration method revealed negative result. Trypsin activity test of stool revealed low trypsin activity as compared with normal specimen. Daily fecal fat exceeded upper normal limit. The diagnosis of giardiasis was confirmed by duodenal juice examination. Intestinal histology revealed mild shortening of the villi with increased mononuclear cell infiltration in the lamina propria. The daily stool amount decreased markedly after treatment with metronidazole 250 mg three times a day for 7 days. The edema subsided during the treatment. Serum albumin bevel returned to normal after the treatment. Giardiasis with malabsorption syndrome has often been overlooked in Taiwan. It is advised that in case of malabsorption syndrome giardiasis should be included in the list of differential diagnosis.

Inhibition of Ca2+/calmodulin-dependent protein kinase II by arachidonic acid and its metabolites

A variety of evidence indicates that activation of Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) in nerve terminals leads to enhanced neurotransmitter release. Arachidonic acid and its 12-lipoxygenase metabolite, 12-hydroperoxyeicosatetraenoic acid (12-HPETE), have been suggested to act as second messengers mediating presynaptic inhibition of neurotransmitter release. In the present study it was found that CaM-kinase II, purified from rat brain cortex, was inhibited both by arachidonic acid (IC50 = 24 microM) and by 12-HPETE (IC50 = 0.7 microM). Neither substance inhibited CaM-kinase I or III, protein kinase C, or the catalytic subunit of cAMP-dependent protein kinase. Specific inhibition of Ca2+/calmodulin-dependent protein phosphorylation by arachidonic acid was also demonstrated in intact synaptic terminals (synaptosomes) isolated from rat forebrain. These results suggest that arachidonate and its metabolites may modulate synaptic function through the inhibition of CaM-kinase II-dependent protein phosphorylation.

Arrhythmogenic right ventricular dysplasia: report of one case

Arrhythmogenic right ventricular dysplasia is a rare disease that sometimes leads to sudden death in young people. In this report, we describe our experience with diagnosis and treatment of a case of arrhythmogenic right ventricular dysplasia.

Calcium/diacylglycerol-dependent protein kinase and its major 87-kilodalton protein substrate are differentially distributed in rat basal ganglia

When brain tissue is subjected to subcellular fractionation, both calcium/diacylglycerol-dependent protein kinase (protein kinase C) and an 87-kilodalton (kDa) protein substrate for this enzyme are enriched in the crude nerve terminal fraction. The present study, using chemical and surgical lesions of neurons in the rat neostriatum and substantia nigra, has examined whether the 87-kDa protein is colocalized with protein kinase C in identified neurons and nerve terminals. Our results show that, in the basal ganglia, protein kinase C is highly enriched in local striatal neurons and the striatonigral fibers and terminals. In contrast, the 87-kDa protein appears to be widely and evenly distributed in both neuronal and nonneuronal cells. The 87-kDa protein may therefore mediate functions of protein kinase C not restricted to nerve terminals.

Translocation of synapsin I in response to depolarization of isolated nerve terminals

Depolarization of isolated nerve terminals (synaptosomes) has been shown to stimulate neurotransmitter release and to increase the phosphorylation state of a number of proteins, including synapsin I, in a Ca2+-dependent manner. Synapsin I, a prominent nerve terminal phosphoprotein, interacts with the cytoplasmic surface of small synaptic vesicles and with cytoskeletal elements in a phosphorylation-dependent manner. In the present study we have found that depolarization of synaptosomes resulted in a rapid (2-5 sec) translocation of synapsin I from the particulate to the cytosolic (soluble) fraction. This translocation of synapsin I correlated with its phosphorylation state and was dependent on the presence of Ca2+ in the incubation medium. The stoichiometry of phosphorylation of soluble synapsin I was considerably higher than that of synapsin I in the particulate fraction, under both basal and depolarizing conditions. These data are consistent with the hypothesis that, in situ, the phosphorylation of synapsin I promotes its translocation from synaptic vesicles/cytoskeleton to the cytosol. This phosphorylation/translocation may be instrumental in regulating the release of neurotransmitter.

Echocardiographic changes following balloon valvuloplasty in valvular pulmonic and aortic stenosis

Nineteen patients with pulmonary valvular stenosis and two with aortic valvular stenosis, aged 20 days to 12 years, were studied before and after balloon dilatation valvuloplasty (BDV) by M-mode, 2-D, pulsed wave (PW) and continuous wave (CW) Doppler, and color flow mapping echocardiography. In those with pulmonary stenosis, a dome-shaped valve was found in 16(84%) of 19 cases before BDV, and the valve remained dome shaped only in 4(27%) of 15 after procedure (P less than 0.001). Restricted valve motion which was noted in 18(95%) of 19 before BDV, persisted only in 2(13%) of 15 after procedure (P less than 0.001). Thickening of the pulmonic valve and poststenotic dilatation of the main pulmonary artery stayed almost unchanged. The pressure gradient across the pulmonic valve measured by cardiac catheterization and CW Doppler agreed well (r = 0.862). Echocardiographic evidence of pulmonary regurgitation was detected in 1(25%) of 4 patients before, and 7(50%) of 14 after BDV. In two patients with aortic stenosis, the echocaardiograms showed the valve was thickened and dome-shaped. Following BDV, echocardiographic evidence of mild aortic regurgitation was observed only in one patient who had had such a regurgitationn before BDV. The diameter of the valve annulus measured on 2-D echo and angiocardiograms correlated well (r = 0.912), and it stayed unchanged following BDV. It is concluded that 2-D and Doppler echocardiographic examinations proved to be useful in the measurement of valve annulus, delineation of stenotic semilunar valves and monitoring of the efficacy of BDV.

Reconstruction of right ventricular outflow tract by autologous pericardial tri-semilunar valve with sinus of Valsalva: report of a case with absent pulmonary valve

The choice of a valved conduit or a valve in the right ventricular outflow tract remains a problem. We propose to reconstruct the pulmonary valve inside the patient's own pulmonary trunk by autologous pericardium in tri-semilunar fashion with concomitant formation of the sinus of Valsalva and commissure. This operation was carried out on a 7-year-old girl suffering from Fallot's tetralogy with an absent pulmonary valve. The ventricular septal defect was repaired and the pulmonary valve reconstructed as above. The postoperative cross-sectional echocardiogram, color Doppler echocardiogram and angiogram showed a pliable tri-semilunar valve across the pulmonary outflow tract without regurgitation. It is concluded that firstly, the sinus of Valsalva is indispensable for a stentless semilunar valve to be competent; secondly, reconstruction of the semilunar valve inside the pulmonary trunk by autologous pericardium is recommended for the absent pulmonary valve syndrome, but the long-term fate of this pericardial valve awaits further evaluation.

Mesenchymal-epithelial interactions between normal and transformed human bladder cells

Epithelial cells obtained from normal human urothelium, a cell line derived from a papillary bladder carcinoma, and cells derived from an invasive carcinoma were grown in a serum-free fully defined medium. The interaction between these cell types and normal bladder stromal cells obtained by explant culture in serum were investigated in mixed cultures. These studies showed that normal urothelium was not responsive to the growth factors produced by cultured bladder fibroblasts and the cells did not grow at increased rates in association with living fibroblast layers. Cells derived from a papillary human bladder carcinoma cell line also did not associate well with fibroblast layers or show marked stimulation of growth by preformed layers of fibroblast cells. On the other hand, cells of the EJ carcinoma line, originally derived from a patient with highly invasive disease, easily infiltrated fibroblast layers and were strongly stimulated to grow by the presence of the stromal cells. This model system might therefore be used to determine key elements associated with malignant progression in human bladder carcinoma.

Phosphorylation and associated translocation of the 87-kDa protein, a major protein kinase C substrate, in isolated nerve terminals

A protein of 87 kilodaltons (87 kDa) was previously identified as a major specific substrate for protein kinase C in neuronal and other tissues. We have now studied the effect of protein kinase C-catalyzed phosphorylation of this protein on its association with membranes in isolated nerve terminals (synaptosomes) from rat cerebral cortex. Incubation of synaptosomal membranes under conditions associated with activation of protein kinase C led to the release of the phosphorylated 87-kDa protein into the incubation medium. In intact synaptosomes, activation of protein kinase C by phorbol esters or by depolarization-induced Ca2+ influx caused an increased phosphorylation of the 87-kDa protein and its translocation from membrane to cytosol. This translocation showed time courses, calcium dependency, and reversibility similar to those observed for the protein kinase C-induced phosphorylation of the protein. These results suggest that protein kinase C-catalyzed phosphorylation of the 87-kDa protein is responsible for its subcellular translocation into the cytosol of nerve terminals.

Color flow mapping in perimembranous ventricular septal defect with left ventricular-to-right atrial shunts

The natural history of ventricular septal defect (VSD) varies with the exact location of the defect and also with the tissue changes surrounding it. Seven cases of perimembranous trabecular VSD were noted during color Doppler echocardiographic examination to have left ventricular-to-right atrial (LV-to-RA) shunts in association with aneurysmal transformation of VSD. Repeated cardiac catheterization documented the role of aneurysmal transformation in the increase of LV-to-RA shunts. A VSD located near the antero-septal commissure was diagnosed in all cases by echocardiography from the apical 5-chamber and parasternal inflow views. Echocardiographic signs of LV-to-RA shunts are high velocity backward turbulence in the RA without the presence of an elevated right ventricular systolic pressure and a two-directional turbulence through the "transformed" VSD. Corrective surgery confirmed the diagnosis in one case. Another case was complicated by an episode of viridans streptococcal endocarditis. The significance of LV-to-RA shunts in perimembranous trabecular VSD remains unknown.

Autophosphorylation and activation of Ca2+/calmodulin-dependent protein kinase II in intact nerve terminals

The autophosphorylation of purified Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II) on a threonine-containing phosphopeptide common to both the alpha and beta subunits was previously shown to convert this enzyme into a catalytically active Ca2+-independent species. We now have examined the phosphorylation and activation of Ca2+/CaM kinase II in synaptosomes, a Ca2+-dependent neurosecretory system consisting of isolated nerve terminals. Synaptosomes were prelabeled with 32Pi and the alpha subunit of Ca2+/CaM kinase II was immunoprecipitated. Under basal incubation conditions the alpha subunit was phosphorylated. Depolarization of synaptosomes produced a rapid (2-5 s) Ca2+-dependent increase of about 50% in the state of phosphorylation of the alpha subunit. This was followed by a slower increase in the 32P content of the alpha subunit over the next 5 min of depolarization. The enhanced phosphorylation was characterized by an initial rise (2 s) and subsequent decrease (30 s) in the phosphothreonine content of the alpha subunit. In contrast, the phosphoserine content of the alpha subunit slowly increased during the course of depolarization. Thermolytic two-dimensional phosphopeptide maps of the alpha subunit demonstrated that depolarization stimulated the labeling of a phosphopeptide associated with autoactivation. In parallel experiments, unlabeled synaptosomes were depolarized, and lysates of these synaptosomes were assayed for Ca2+/CaM kinase II activity. Depolarization produced a rapid (less than or equal to 2 s) increase in Ca2+-independent Ca2+/CaM kinase II activity. This activity returned to basal levels by 60 s. Thus, depolarization of intact synaptosomes is associated with the transient phosphorylation of Ca2+/CaM kinase II on threonine residues, presumably involving an autophosphorylation mechanism and concomitantly the transient generation of the Ca2+-independent form of Ca2+/CaM kinase II.

Clinical implications of atrial isomerism

Right atrial isomerism or left atrial isomerism is frequently diagnosed as situs ambiguous without further discrimination of the specific morbid anatomy. Thirty six cases of right atrial isomerism and seven cases of left atrial isomerism were collected from the records and pathological museum at the National Taiwan University Hospital. There was a necropsy report for 18 cases. In all patients one or more of the following conditions was met: (a) isomeric bronchial anatomy, (b) echocardiographic and angiocardiographic evidence of isomerism, and (c) surgical or necropsy evidence of abnormal atrial anatomy. An anomalous pulmonary venous connection was present in 55% of patients with right atrial isomerism; in left atrial isomerism one case (14%) had a partial anomalous pulmonary venous connection. Forty per cent of cases of anomalous pulmonary venous connection with right atrial isomerism had obstruction. Six (86%) of seven cases with left atrial isomerism had an ambiguous biventricular atrioventricular connection. In contrast, univentricular atrioventricular connection (26 of 36, 72%) was significantly more common in right atrial isomerism. A common atrioventricular valve was the most frequent mode of connection in both forms. Two discrete atrioventricular valves were significantly more common in left atrial isomerism. Atrioventricular valve regurgitation was detected in 14 cases. Double outlet right ventricle was the most common type of ventriculoarterial connection. The most commonly cited causes of death after either palliative or definitive operation were undetected anomalous pulmonary venous connection, pulmonary venous stricture, and uncorrected atrioventricular valve or aortic regurgitation complicated by abnormal coagulation. Although the prognosis is poor, successful operation depends on knowledge of the precise anatomical arrangement associated with atrial isomerism.

Membrane depolarization and carbamoylcholine stimulate phosphatidylinositol turnover in intact nerve terminals

Synaptosomes, purified from rat cerebral cortex, were prelabeled with [3H]inositol to study phosphatidylinositol turnover in nerve terminals. Labeled synaptosomes were either depolarized with 40 mM K+ or exposed to carbamoylcholine (carbachol). K+ depolarization increased the level of inositol phosphates in a time-dependent manner. The inositol trisphosphate concentration increased rapidly and transiently, reaching maximum (250% of control) in less than 3 sec and returning to near basal levels by 30 sec. The inositol bisphosphate level also increased rapidly, but its elevated level (220% of control) was sustained during continued depolarization. The elevated level of inositol bisphosphate was reversed upon repolarization of the synaptosomes. The level of inositol monophosphate increased slowly to 120-130% of control. These effects of K+ depolarization depended on the presence of Ca2+ in the incubation medium. Carbachol stimulated the turnover of phosphatidylinositol in a dose- and time-dependent manner. The level of inositol trisphosphate increased only slightly (120-130% of control) during carbachol stimulation. The level of inositol bisphosphate increased to 210% of control, and this maximal response was seen from 15 to 60 min. Accumulation of inositol monophosphate (250% of control) was larger than that of inositol bisphosphate, but its time course was slower. Atropine and pirenzepine inhibited the carbachol effect with high affinities of 0.8 nM and 16 nM, respectively, indicating that the effect of carbachol was mediated by activation of a M1 muscarinic receptor. Incubation of synaptosomes in Ca2+-free buffer reduced the response to carbachol by 30%, and addition of EGTA abolished it. These data show that both Ca2+ influx and M1 muscarinic receptor activation stimulate phospholipase C activity in synaptosomes, suggesting that phosphatidylinositol turnover may be involved in regulating neurotransmitter release from nerve terminals.

Stimulus-dependent myristoylation of a major substrate for protein kinase C

Bacterial lipopolysaccharide (LPS), the major surface component of gram-negative bacteria, exerts a profound effect on the immune system by enhancing the release of proteins and arachidonic acid metabolites from macrophages (for review see ref. 1). The molecular mechanism(s) by which LPS induces these various secretory responses is unknown. We previously reported that LPS promotes the myristoylation of several macrophage proteins including one with a relative molecular mass (Mr) of 68K2. We have now found that by several criteria the 68K myristoylated protein is similar or identical to the 80/87K protein, a major specific substrate for protein kinase C (PKC) found in brain and fibroblasts (for review see refs 7,8). We have also found that the myristoylated PKC substrate is quantitatively associated with the membrane fraction. Myristoylation of the PKC substrate may target it to the membrane and constitute a transduction pathway for stimulus-response coupling.

Protein tyrosine phosphorylation in synaptic vesicles

Protein tyrosine phosphorylation in purified synaptic vesicles from rat forebrain has been studied in the presence of Mn2+ and orthovanadate. High levels of endogenous protein tyrosine phosphorylation were observed. Four major phosphoproteins, with apparent molecular masses of 105, 94, 38, and 30 kDa, were shown to contain phosphotyrosine. The 38-kDa phosphoprotein was identified as synaptophysin (p38), a well-characterized integral membrane protein of synaptic vesicles. The three other phosphotyrosine-containing proteins distributed in the same manner as synaptophysin in all subcellular fractions. Like synaptophysin, the two high molecular weight phosphotyrosine proteins (105 and 94 kDa) were found to be glycoproteins by lectin chromatography. Tyrosine phosphorylation of synaptophysin was an intravesicular reaction and reached 50% of maximal level within 3 min. Triton X-100, a nonionic detergent, inhibited tyrosine phosphorylation of endogenous protein substrates but not the phosphorylation of an exogenous substrate, poly(Glu80,-Tyr20). Tyrosine phosphorylation of synaptophysin was also demonstrated in synaptosomes, indicating that tyrosine phosphorylation of synaptic vesicle proteins occurs in intact nerve terminals.

Protein phosphorylation in nerve terminals: comparison of calcium/calmodulin-dependent and calcium/diacylglycerol-dependent systems

Rat cerebral cortical synaptosomes that had been prelabeled with 32P-orthophosphate were exposed to either (1) K depolarization which causes Ca2+ influx and hence would be expected to activate Ca2+-dependent enzymes, including Ca2+/calmodulin-dependent and Ca2+/diacylglycerol-dependent protein kinases (Ca/CaM kinases and protein kinase C, respectively); or (2) phorbol esters or 1-oleoyl-2-acetyl-glycerol (OAG), which selectively activate protein kinase C. Proteins whose state of phosphorylation was affected by these treatments could be divided into 3 classes. Class A includes 5 phosphoproteins that showed rapidly increased phosphorylation by synaptosomal depolarization but not by OAG or phorbol ester. Four of these proteins, synapsins Ia and Ib and proteins IIIa and IIIb, are neuron-specific, synaptic vesicle-associated proteins known to be substrates for Ca/CaM kinases I and II. These phosphoproteins were rapidly dephosphorylated upon synaptosomal repolarization. Class B is composed of 2 phosphoproteins that showed rapidly increased phosphorylation by either synaptosomal depolarization or treatment with phorbol ester or OAG. These 2 acidic proteins of Mr87 and 49 kDa are known from in vitro studies to be specific substrates for protein kinase C. Thermolytic peptide mapping indicated that the 87 kDa protein in synaptosomes was phosphorylated by protein kinase C in situ. These 2 phosphoproteins were slowly dephosphorylated upon synaptosomal repolarization. Class C comprises 4 phosphoproteins that were rapidly dephosphorylated upon synaptosomal depolarization and may be substrates for Ca2+-activated protein phosphatase(s). These data suggest that Ca2+ influx into nerve terminals activates Ca/CaM kinases I and II, protein kinase C, and unidentified protein phosphatase(s).(ABSTRACT TRUNCATED AT 250 WORDS)

Phorbol ester enhancement of neurotransmitter release from rat brain synaptosomes

Neurotransmitter release from rat brain synaptosomes was measured following pretreatment with various phorbol esters. Ca2+-dependent, evoked neurotransmitter release was increased by phorbol esters that were active in stimulating protein kinase C. Protein kinase C activation was demonstrated by increased incorporation of 32P into 87-kilodalton phosphoprotein, a specific substrate for that kinase. Inactive phorbol esters had no effect on neurotransmitter release or on the phosphorylation of 87-kilodalton phosphoprotein. The increased release was observed in either crude cortical synaptosomal fractions (P2) or purified cortical synaptosomal fractions. The enhancement was found for all neurotransmitters (norepinephrine, acetylcholine, gamma-aminobutyric acid, serotonin, dopamine, and aspartate), all brain regions (cerebral cortex, hippocampus, and corpus striatum), and all secretagogues (elevated extracellular K+ level, veratridine, or A23187) examined. It was also observed at all calcium concentrations present during stimulation of release. The phorbol ester enhancement of Ca2+-dependent release occurred whether or not calcium was present during pretreatment. These results indicate that stimulation of protein kinase C leads to an enhanced sensitivity of the stimulus-secretion coupling processes to calcium within the nerve terminal. The results support the possibility that presynaptic activation of protein kinase C modulates nerve terminal neurotransmitter release in the CNS.

The type-1 protein phosphatase activating factor FA is a membrane-associated protein kinase in brain, liver, heart and muscles

Although the activating factor FA of the type-1 protein phosphatase has long been recognized as a cytosolic enzyme involved in the regulation of cell metabolism and nervous functions, strong indications have been obtained that FA is in fact a membrane-bound protein kinase in most mammalian tissues. For instance, direct treatment of the tissue extracts including brain, liver, cardiac, smooth and skeletal muscles with 1% Triton X-100 can cause several fold stimulation of the FA activity. Moreover, at least 50% of the FA can be detected in the particulate fractions of the extracts. Chromatography of the extracts in the presence and absence of Triton X-100 further demonstrate these results. The data can now explain the reason why most people can not isolate reasonable amount of FA from mammalian tissues. It is recommended that Triton X-100 should be used for purification of FA from most mammalian tissue extracts. The results also suggest that most previous studies on the action of FA involved in the regulation of cell functions should be re-evaluated and the membrane-associated FA should be taken into consideration.

Vitamin D3 derivatives inhibit the differentiation of Friend erythroleukemia cells

A number of vitamin D3 metabolites inhibit benzodiazepine- and dimethyl sulfoxide-induced differentiation of Friend erythroleukemia cells. The inhibition is dose dependent and occurs at nM concentrations. The order of potency of these compounds is 1,25-dihydroxycholecalciferol greater than 1,25,26-trihydroxycholecalciferol greater than 1,24R,25-trihydroxycholecalciferol greater than 1 alpha-hydroxycholecalciferol greater than 24R,25-dihydroxycholecalciferol greater than 25S,26-dihydroxycholecalciferol. The inhibition is maximal when the vitamin D3 analogs are added together with the inducer, and becomes progressively decreased with delayed addition. These results suggest that the vitamin D3 metabolites may play a regulatory role in erythropoiesis.

Downregulation of [3H]Ro5-4864 binding sites after exposure to peripheral-type benzodiazepines in vitro

Peripheral-type benzodiazepine (BZD) binding sites undergo a rapid and pronounced downregulation after exposure to these compounds in vitro. Friend erythroleukemia cells were incubated with micromolar concentrations of BZD after which they were washed thoroughly and the binding of the specific peripheral-type BZD radioligand [3H]Ro5-4864 was determined. Exposure to the peripheral-type BZD Ro7-3351 decreased the number of [3H]Ro5-4864 binding sites from 324 to 41 fmol/10(6) cells with no change in affinity. Downregulation appears to require active cellular processes because it is blocked when exposure to BZD is at 4 degrees C rather than at 37 degrees C. Furthermore, whereas [3H]Ro5-4864 binding is decreased substantially in membrane preparations made from downregulated cells, it is not altered when membrane preparations from control cells are exposed to BZD. The time course of downregulation is quite rapid, as it occurs within minutes. In contrast, the return of sites requires days and there is a close relationship between return of sites and growth of new cells. The ability of BZDs to downregulate correlates more closely with affinity for the peripheral-type site than with biological activity. The ability to undergo downregulation is characteristic of receptors and its occurrence suggests that peripheral-type BZD binding sites are functional receptors.

Intrathecal morphine for post-thoracotomy pain

We wished to investigate possible differences in the duration of postoperative analgesia and the incidence of respiratory depression after the intrathecal injection in the lumbar area of 10 micrograms/kg morphine in hypobaric and hyperbaric solution for relief of post-thoracotomy pain. Twenty-nine patients received morphine plus dextrose (hyperbaric) and 21 received morphine in preservative-free normal saline. The duration of analgesia was longer with the morphine in the normal saline group than in the hyperbaric group (P less than 0.04). One patient developed delayed respiratory depression. Our data support the use of morphine in normal saline mixtures for greater duration of analgesia after thoracic operations.

Widespread occurrence of "87 kDa," a major specific substrate for protein kinase C

An 87-kDa phosphoprotein, identified previously as a major, specific substrate for Ca2+/phospholipid/diacylglycerol-dependent protein kinase (protein kinase C) in broken cell preparations from rat brain, has been characterized with respect to its species, tissue, and subcellular distribution. A similar protein was present in monkey, human, mouse, and bovine brain and in Torpedo californica electric organ. The protein was also identified in a variety of nonneuronal rat and bovine tissues. The rat protein had an apparent molecular mass 4-7 kDa lower, and was slightly more acidic, than the protein in bovine tissues. The 87-kDa proteins from various bovine tissues were identical by the following criteria: each was phosphorylated by exogenous protein kinase C, was of comparable molecular mass, generated multiple spots within the pH range of 4.4-4.9 upon isoelectric focusing, yielded identical patterns upon digestion with Staphylococcus aureus V8 protease, and was recognized by a specific 87-kDa antiserum. The relative concentrations of the 87-kDa protein in bovine tissues were highest in brain, spleen, and lung, moderate in testis, pancreas, adrenal, kidney, and liver, and lowest in heart and skeletal muscle. In the brain, the 87-kDa protein was concentrated in the synaptosomal membrane and in the cytosol. The membrane-bound protein was extractable with nonionic detergents but not with NaCl. This species, tissue, and subcellular distribution of the 87-kDa protein is similar to that of protein kinase C.

Differentiation of Friend erythroleukemia cells induced by benzodiazepines

Many benzodiazepines of the type whose receptors are found in peripheral tissues cause the differentiation of cultured Friend erythroleukemia cells. The maximal level of induction of hemoglobin synthesis is 10-80% of the cells, depending on the compound tested. The induction is concentration and time dependent, requiring micromolar amounts of the drugs and about 5 days of treatment for full expression. The time course is very similar to that observed for a well-studied inducer, dimethyl sulfoxide. The affinities of the agents for the peripheral-type benzodiazepine binding site are not correlated with their capacity to induce differentiation. Also, the biological effect is stereospecific since the (3S) stereoisomer Ro11 -6896 is at least an order of magnitude more potent than its (3R) enantiomer, Ro11 -6893. The benzodiazepine effect exhibits definite structure-activity relationships. A 1-methyl group is an absolute requirement, although this is not sufficient in itself. Hydroxyl and methoxyl groups at the 4' position enhance the biological activity, but 4'-chloro decreases it. Substitutions at the 2', 6', and 4 positions also decrease the biological activity, as does the lack of a 2-carbonyl group. These data suggest that the benzodiazepines act in a specific manner to induce the differentiation of Friend erythroleukemia cells.

Structural requirements for the binding of benzodiazepines to their peripheral-type sites

The DS19 Friend erythroleukemia cells possess peripheral-type benzodiazepine recognition sites that are similar to those characterized in other tissues and cells. These sites recognize only specific and well-defined ligand structures. In order for the benzodiazepines to bind to these sites, an alkyl group of 3 carbons or less is required at position 1, together with a carbonyl group at position 2. In addition, the binding affinity is enhanced by 4'-halogen or 4'-methoxy substituents, and by 7- or 2'-halogens. However, the affinity is decreased by substitutions at position 3 or 4. Central-type benzodiazepine binding in brain, on the other hand, is not affected by 1-alkyl groups and is inhibited by 4'-substitutions. Furthermore, unlike the peripheral-type site, the brain receptor is stereo-selective. These results demonstrate that the two binding sites are fundamentally different in their recognition of benzodiazepine ligands.

Benzodiazepines that bind at peripheral sites inhibit cell proliferation

[3H]Ro5-4864 binds to mouse thymoma cells in a specific, saturable, and reversible manner. Scatchard analysis shows a single class of binding sites with a Kd of 4.4 nM and a Bmax of 477 fmol per 10(6) cells. This benzodiazepine binding site is of the peripheral type, based on the relative potencies of Ro5-4864 and clonazepam in competing for [3H]diazepam binding. Fifteen benzodiazepines that bind to this site with affinities ranging from 6 nM to 1 microM also reversibly inhibit the proliferation of thymoma cells in culture at the micromolar dose range. There is a strong positive correlation (r = 0.85) between the binding constants of these compounds for the peripheral-type sites and their ED50 in inhibiting the uptake of [3H]thymidine into the cells. These sites may be involved in the regulation of thymoma cell proliferation.

Dimerization occurs during the reversible acid inactivation of 2-oxo-4-hydroxyglutarate aldolase from Escherichia coli

Exposure of Escherichia coli 2-oxo-4-hydroxyglutarate aldolase (4-hydroxy-2-oxoglutarate glyoxylate-lyase, EC 4.1.3.16) (molecular weight = 63 000) to phosphoric acid at pH 1.6 for 10 min at 4 degrees C causes 95% or greater inactivation. No significant effect on the rate or extent of inactivation is caused by varied aldolase concentrations or the presence of exogenous proteins. Chloride ion (50-100 mM) or 10 mM 2-oxo-4-hydroxyglutarate markedly decreases both the rate and extent of inactivation; good protection is also afforded by 10 mM pyruvate, glyoxylate, glyoxal, 2-oxoglutarate or 2-oxobutyrate. Whereas native aldolase has two free and three buried sulfhydryl groups, all five are exposed in the acid-inactivated enzyme and the molecular weight of this species at pH 1.6 is 126 000. Ultraviolet absorbance difference spectra, circular dichroism spectra and ultracentrifugation studies establish that the inactivation process is characterized by an alteration of secondary and tertiary structure as well as an aggregation to a dimer of the native molecule. Reactivation of enzyme activity to 60-80% of the original level is seen within 20 min at pH 6 to 8; examination of inactivation/reactivation as a function of pH indicates that these two processes occur via kinetically distinct pathways. Native and reactivated enzymes are identical in molecular weight, sulfhydryl titer, Km and alpha-helix content.

The binding of [3H]-diazepam to guinea-pig ileal longitudinal muscle and the in vitro inhibition of contraction by benzodiazepines

1--The longitudinal muscle-myenteric plexus strip preparation of the guinea-pig ileum was used to study the binding of [3H]-diazepam and the effect of benzodiazepines on its contraction. 2--Scatchard analysis of binding indicated a single class of binding sites with KD = 43 nM and Bmax = 229 fmol/mg prótein. Binding was of peripheral type based on the much greater binding affinity of Ro5-4864 as compared to clonazepam. Binding of [3H]-diazepam reached equilibrium at 10 min and dissociated rapidly (T1/2 = 1.3 min). The KD derived from the rate constants agreed with that from the Scatchard analysis. 3--Benzodiazepines produced a dose-dependent decrease in the electrically induced contractions of the longitudinal muscle strip, but their potencies in this effect did not correlate with their binding affinities. 4--Diazepam antagonized the contractions of the longitudinal muscle strip induced by K+, Ca2+, histamine and carbachol. The inhibition of Ca2+-induced contractions was reversed by increasing the concentration of Ca2+ in the medium.

The structure of bovine rhodopsin

We have isolated 16 peptides from a cyanogen bromide digest of rhodopsin. These cyanogen bromide peptides account for the complete composition of the protein. Methionine-containing peptides from other chemical and enzymatic digests of rhodopsin have allowed us to place the cyanogen bromide peptides in order, yielding the sequence of the protein. We have completed the sequence of most of the cyanogen bromide peptides. This information, in conjunction with that from other laboratories, forms the basis for our prediction of the secondary structure of the protein and how it may be arranged in the disk membrane.

[Incidence of hepatotoxic side effects during antituberculous therapy (INH, RMP, EMB) in relation to the acetylator phenotype (author's transl)]

In 95 patients with active tuberculosis, we investigated in a prospective study the influence of the acetylator phenotype on the hepatotoxic side effects of the antituberculous regimen isoniazid (INH) 10 mg/kg, rifampicin (RMP) 10 mg/kg, and ethambutol (EMB) 25 mg/kg. Besides a much higher incidence of isoniazid hepatitis (SGOT, SGPT greater than 200 U/l) in 12.6% of patients treated--as compared to the incidence reported in large chemoprophylaxis trials with isoniazid monotherapy in the range of 0.5%-1% (IUAT 1969, U.S.P.H.S. 1971)--we observed a significant, higher risk of isoniazid-induced hepatotoxicity in slow acetylators (p less than 0.01): in 26 of 56 slow acetylators (= 46.4%), but only in 4 of 30 rapid acetylators (=13.3%) were transaminases in the serum elevated greater than 50 U/l. The 12 patients with the most severe hepatotoxic side effects (SGOT, SGPT greater than 200 U/l) were all slow acetylators. Women developed severe hepatic injury more often than men (p less than 0.05). In cases with isoniazid hepatitis, triple therapy was either stopped or reduced to a combination RMP, EMB. In cases with less severe liver injury, triple therapy was continued. In all patients transaminases normalized within 2-4 weeks. On return to full triple therapy, none of the patients developed new elevation of transaminases. The constant occurrence of isoniazid hepatitis during the 2nd-4th week (19 +/- 7 days) as well as the normalization without any new hepatotoxic reaction suggest that there may be an interaction between RMP and isoniazid metabolism limited to the early phase of chemotherapy.

Steady-state kinetics and inhibition studies of the aldol condensation reaction catalyzed by bovine liver and Escherichia coli 2-keto-4-hydroxyglutarate aldolase

Two sensitive assays, one which fluorometrically measures only the L isomer of 2-keto-4-hydroxyglutarate after decarboxylation to L-malate and the other which spectrophotometrically determines both enantiomers by reductive amination with glutamate dehydrogenase, are described. By use of these assays, the steady-state kinetics of the aldol condensation of pyruvate with glyoxylate, as catalyzed by 2-keto-4-hydroxyglutarate aldolase from either bovine liver or Escherichia coli, were studied as was the inhibition of this reaction by glyoxylate and other anions. For the E. coli aldolase, double-reciprocal plots are linear except at high (above 5 mM) glyoxylate concentrations; apparent Km values increase with increasing concentrations of the fixed substrate. The data are consistent with an ordered reaction sequence. Inhibition by halides follows the lyotropic or Hofmeister series. Esters are not good inhibitors; mono-, di-, and tricarboxylic acids are increasingly inhibitory. Of the substrate analogues tested, hydroxypyruvate is the most potent inhibitor. Inhibition studies with citrate, acetaldehyde, and glyoxylate (all competitive inhibitors) suggest there are two domains at the active site-the Schiff base forming lysyl residue which interacts with carbonyl analogues (like acetaldehyde) and a center of positive charge which binds anions (like citrate). In contrast to the bacterial enzyme, liver 2-keto-4-hydroxyglutarate aldolase is inhibited in a competitive manner by much lower concentrations (0.1 mM or even lower) of glyoxylate. Many salts and some carboxylic acids activate the liver enzyme. Similarly, substrate analogues like 2-ketobutyrate and fluoropyruvate are mild activators; no effect is seen with acetaldehyde. Besides glyoxylate, only glyoxal, 2-ketoglutarate, and hydroxypyruvate inhibit the aldol condensation reaction. A uniform value of 1 is found for the number of inhibitor molecules bound per active site of either liver or E. coli 2-keto-4-hydroxyglutarate aldolase.

Site of attachment of 11-cis-retinal in bovine rhodopsin

A dipeptide containing the binding site for retinal in bovine rhodopsin has been isolated and its sequence determined. Rhodopsin containing [11-3H]retinal was prepared in chromatographically pure form, and the [3H]retinal was reductively linked to its binding site on opsin by using borane--dimethylamine. The [3H]retinylopsin in octyl glucoside was exhaustively digested with Pronase, and its peptides were separated on silica gel in chloroform/methanol/ammonia [Bownds, D. (1967) Nature (London) 216, 1178--1181] followed by silica gel thin-layer chromatography in two solvent systems. The major retinyl peptide was shown to be alanyl-N epsilon-retinyllysine by amino acid composition, 3H content, and amino acid sequence analysis. The retinyl binding site is located in the carboxyl-terminal region of rhodopsin: when rod cell disk membranes containing [3H]retinal rhodopsin were digested with thermolysin and then reacted with sodium borohydride or borane--dimethylamine, [3H]retinal was reduced onto the F2 (Mr congruent to 6000) fragment, which derives from rhodopsin's carboxyl-terminal region.

Topography of rhodopsin in rod outer segment disk membranes. Photochemical labeling with N-(4-azido-2-nitrophenyl)-2-aminoethanesulfonate

Rod cell disk membranes have been photochemically reacted with the water-soluble, membrane-impermeable nitrene precursor N-(4-azido-2-nitrophenyl)-2-aminoethane-sulfonate [NAP-taurine, NAPT]. Rhodopsin, minor membrane proteins, and lipids all incorporate the (nitrophenyl)[35S]taurine (NPT) label. We also find that rhodopsin may be labeled in the dark using prephotolyzed NAPT. This reaction is presumably due to long-lived photoproducts of NAPT. NAPT modifies rhodopsin in the membrane in a selective manner; some cyanogen bromide peptides of NPT-rhodopsin contain appreciable NPT label and some contain essentially none. Precise specific radioactivities could not be determined for the [35S]NPT-peptides since loss of label from some of the peptides was observed during purification procedures. Rhodopsin's carboxyl-terminal cyanogen bromide peptides are well labeled when the protein is modified in disk membranes but the amino-terminal peptide is poorly labeled. When rhodopsin is labeled in reconstituted membranes in which both surfaces of rhodopsin are accessible to reagent, labeling of rhodopsin's amino-terminal peptide is enhanced. These results are consistent with a model in which rhodopsin's carboxyl-terminal region is located at the cytoplasmic (external) surface of disk membranes and its amino terminus is located at the intradiskal membrane surface.

Methylthiohydantoin amino acids: chromatographic separation and comparison to phenylthiohydantoin amino acids

Most phenylthiohydantoin (PTH) amino acids and most methylthiohydantoin (MTH) amino acids may be separated from one another by thin-layer chromatography (TLC) using the same sequential development technique with the same two solvents. Similarly, a single solvent system may be used in high-performance liquid chromatography (HPLC) to separate most PTH-amino acids and most MTH-amino acids. When both TLC and HPLC separations are performed on a sample, all MTH-and PTH-amino acids can be uniquely identified. Since many solid-phase protein sequencing techniques generate both MTH-and PTH-amino acids, these analytical systems simplify identification of the amino acid derivatives. Although the chromatographic properties of MTH-and PTH-amino acids are similar, they are not identical (contrary to a previous report).

Herpes zoster reactivation of phantom limb pain

A case is reported in which a herpes zoster infection caused recurrence of phantom limb pain in a man whose left arm had been amputated 7 years previously. It is, to our knowledge, the first such case reported, and it shows the importance of peripheral mechanisms in the generation of phantom limb pain.