Doppler echocardiographic evaluation of left ventricular diastolic function after percutaneous transluminal coronary angioplasty for unstable angina pectoris or acute myocardial infarction

The effect of percutaneous transluminal coronary angioplasty (PTCA) on left ventricular (LV) diastolic function has not been systematically investigated in patients treated for unstable angina or ischemia after acute myocardial infarction (AMI). To assess the relation between reduction of stenosis severity and improvement in diastolic function in this setting, 42 patients with either unstable angina (n = 22) or post-AMI ischemia (n = 20) were serially monitored by Doppler echocardiography 8 +/- 5 hours before and 2 +/- 1 days after PTCA. Doppler LV filling indexes included isovolumic relaxation time, mitral deceleration time, E/A peak velocity ratio and atrial filling fraction. Eighteen aged-matched control subjects served to establish normal values for comparison. Before PTCA, both groups exhibited abnormal diastolic function demonstrated by prolonged isovolumic relaxation time and mitral deceleration time, decreased E/A ratio and increased atrial filling fraction. After PTCA isovolumic relaxation time and deceleration time decreased 18 +/- 28 (p less than 0.005) and 33 +/- 43 ms (p less than 0.002) in the unstable angina group and 18 +/- 23 (p less than 0.003) and 14 +/- 34 ms (difference not significant), respectively, in the post-AMI ischemia group. An increase in E/A ratio and a decrease in atrial filling fraction occurred in both groups; however, these changes were significant only in patients with post-AMI ischemia (+21%, p less than 0.03 and -11.4%, p less than 0.005, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Reversible segmental left ventricular dysfunction after coronary angioplasty

Patients with chronic segmental myocardial dysfunction may demonstrate improvement after coronary revascularization. To evaluate the early effects of percutaneous transluminal coronary angioplasty (PTCA) on resting left ventricular segmental function, we obtained serial two-dimensional echocardiograms 1.1 +/- 0.9 days before and 3.1 +/- 2 days after elective PTCA in 40 patients. Echocardiograms were reviewed in a blind fashion; left ventricular segmental wall motion was analyzed in four short-axis views, and a score was assigned to each region (0, normal; 1, hypokinetic; and 2, akinetic). Abnormal regional wall motion was present in 20 of the patients before PTCA. Summed segment scores in these 20 patients showed an improvement in regional wall motion from 4.5 +/- 2.5 to 1.6 +/- 2.1 (p less than 0.01) after successful PTCA. Similar results were obtained when the patients were divided into those with or without a previous myocardial infarction. Improvement occurred in the seven patients without a previous myocardial infarction; the summed segment score decreased from 4.2 +/- 3.4 to 0.86 +/- 1.6 (p less than 0.05) after PTCA. Ten of the 13 patients with a prior myocardial infarction demonstrated improvement in wall motion after PTCA; the summed segment scores decreased 54% (p less than 0.001). Of the 260 segments analyzed in the study, 180 were normal before and after PTCA. Forty-nine of the 69 hypokinetic segments were normal, and 10 of 12 akinetic segments were hypokinetic after successful coronary revascularization. There was no deterioration in wall motion after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hyperosmotic challenge on basolateral membrane potential in rabbit urinary bladder

In the rabbit urinary bladder, serosal hyperosmotic challenge (SHOC) with either 33 mM NaCl or 66 mM mannitol caused basolateral membrane potential (Vbl) to initially depolarize from -52.6 +/- 1.6 to -48.4 +/- 1.4 mV, followed by a recovery of Vbl to -57.5 +/- 1.3 mV after 13.7 +/- 1.0 min. The voltage recovery was dependent on both serosal HCO3- and Cl-, and in the absence of both, Vbl depolarized to -11.6 +/- 1.5 mV and the ratio of apical-to-basolateral resistance (Ra/Rbl) decreased from 21.0 +/- 3.4 to 8.3 +/- 3.1. This decrease in Ra/Rbl and consequent depolarization of Vbl is caused by a decrease in basolateral K+ conductance. Replacement of serosal Cl- with NO3- or SCN- followed by SHOC caused a sustained depolarization of Vbl to -32.5 +/- 4.4 and -40.9 +/- 0.9 mV, respectively. However, when Br- was used to replace Cl-, voltage recovery occurred but was slowed (24.0 +/- 2.7 min) and reduced in magnitude (-47.5 +/- 3.5 mV). Addition of amiloride (1 mM) or niflumic acid (100 microM), but not bumetanide (1 microM), to the serosal bathing solution inhibited voltage recovery causing Vbl to depolarize to -36.3 +/- 2.6 and -41.5 +/- 4.5 mV, respectively. Serosal addition of ouabain after SHOC caused Vbl to depolarize by 10.8 +/- 0.9 mV in 2 min. We speculate that the SHOC-induced initial depolarization of Vbl is a loss of Ba2(+)-sensitive K+ conductance caused by cell shrinkage. The subsequent repolarization/hyperpolarization of Vbl is caused by an enhanced basolateral membrane Na+ pump current and a reappearance of the Ba2(+)-sensitive K+ conductance. The parallel operation of Na(+)-H+ and Cl(-)-HCO3- exchanges will then supply Na+ for the pump current and, via cellular accumulation of Na+, K+, and Cl-, might result in a partial recovery of cell volume and thus Ba2(+)-sensitive K+ conductance.

Mercury levels in the plumage of red-billed gulls Larus novaehollandiae scopulinus of known sex and age

Samples of 4-8 small body feathers were taken from 27 chicks and 35 adult red-billed gulls caught at their nests on the Kaikoura Peninsula, New Zealand, in December 1988. The adults had been ringed as chicks and were of known ages from 2 to 15 years old. Analysis of total mercury in the feather samples showed that levels were independent of sex and age in adults. Mean fresh weight concentration in adult body feathers was 2.4 microg g(-1). The lack of age accumulation of mercury in gull feathers contrasts with the well known age related accumulation of mercury in tissues of fish and marine mammals, but agrees with predictions of recent studies on mercury dynamics in birds. Mercury levels in chick feathers were about 80% of levels in adult feathers.

The microtubule binding domain of microtubule-associated protein MAP1B contains a repeated sequence motif unrelated to that of MAP2 and tau

We report the complete sequence of the microtubule-associated protein MAP1B, deduced from a series of overlapping genomic and cDNA clones. The encoded protein has a predicted molecular mass of 255,534 D and contains two unusual sequences. The first is a highly basic region that includes multiple copies of a short motif of the form KKEE or KKEVI that are repeated, but not at exact intervals. The second is a set of 12 imperfect repeats, each of 15 amino acids and each spaced by two amino acids. Subcloned fragments spanning these two distinctive regions were expressed as labeled polypeptides by translation in a cell-free system in vitro. These polypeptides were tested for their ability to copurify with unlabeled brain microtubules through successive cycles of polymerization and depolymerization. The peptide corresponding to the region containing the KKEE and KKEVI motifs cycled with brain microtubules, whereas the peptide corresponding to the set of 12 imperfect repeats did not. To define the microtubule binding domain in vivo, full-length and deletion constructs encoding MAP1B were assembled and introduced into cultured cells by transfection. The expression of transfected polypeptides was monitored by indirect immunofluorescence using anti-MAP1B-specific antisera. These experiments showed that the basic region containing the KKEE and KKEVI motifs is responsible for the interaction between MAP1B and microtubules in vivo. This region bears no sequence relationship to the microtubule binding domains of kinesin, MAP2, or tau.

Organization of microtubules in dendrites and axons is determined by a short hydrophobic zipper in microtubule-associated proteins MAP2 and tau

Here we report that the microtubule-associated proteins MAP2 and tau share two separable functional domains. One is the microtubule-binding site which serves to nucleate microtubule assembly; the second is a short C-terminal alpha-helical sequence which can crosslink microtubules by means of a hydrophobic zipper interaction into dense stable parallel arrays characteristic of axons or dendrites. Thus, interactions between molecules of a single type are capable of drastically reorganizing microtubules and completely suppressing their dynamic properties.

Study of the performance of 5 French and 7 French catheters in coronary angiography: a functional comparison

The functional efficacy of a conventional 7F (high flow) coronary catheter (hand injection) was compared with a 5F (high flow) catheter using hand and powered injection in 29 patients with ischemic heart disease. Patients were randomized to 5F or 7F catheters as the initial catheter. Consecutive comparative coronary angiograms were performed in the 15 degrees right anterior oblique (RAO) view using Judkin's technique. Visual diagnostic grade (Grade 1 = Diagnostic, Grade 2 = Equivocal, Grade 3 = Nondiagnostic), vessel filling, vessel density (using a densitometer and corrected for background), streaming, and dislodgement were all evaluated independently by two experienced angiographers with correlation of results. Mean diagnostic grade (1.31 +/- 0.48) was significantly better with the 7F compared to 5F (hand) 1.72 +/- 0.81 and 5F (power) 2.00 +/- 0.71 (P less than or equal to 0.05) for each. Streaming was seen in 55% of injections with 5F (hand) versus 88.5% with 5F (power) and 20.7% with 7F. Measured vessel density was not different for the two catheters. Coronary injection dislodgement occurred significantly more often with 5F power injections than with hand injection of either catheter. Finally, in 6 (30%) of 20 patients in which the 5F was randomly the second catheter used, the operator had to revert to the 7F catheter in order to obtain adequate images. In conclusion, angiographic quality is reduced with 5F catheters compared to 7F high flow in certain patients. Thus, to achieve optimal diagnostic angiograms, larger lumen catheters may be required during certain procedures initially begun with 5F catheters.

Human selenite metabolism: a kinetic model

A model is developed to describe the kinetics of sodium selenite metabolism in humans, based on plasma, urine, and fecal samples obtained from six subjects over a 4-wk period after a single oral 200-micrograms dose of the enriched stable isotope tracer 74Se. The model describes absorption, distributed along the gastrointestinal tract, and enterohepatic recirculation. The model includes four kinetically distinct plasma components, a subsystem consisting of the liver and pancreas, and a slowly turning-over tissue pool. For the six subjects, the ranges of mean residence times for the four plasma components are, respectively, 0.2-1.1 h, 3-8 h, 9-42 h, and 200-285 h; for the hepatopancreatic subsystem 4-41 days; and for the tissue pool 115-285 days. Approximately 84% of the administered dose was absorbed, and after 12 days approximately 65% remained in the body. The model predicts that after 90 days approximately 35% of this Se would be retained, primarily in the tissues. Separating Se metabolism into several distinct kinetic components is a first step in identifying the efficacious, nutritious, and toxic forms of the element.

Simultaneous left ventricular and ascending aortic pressure measurements via single artery access for assessment of aortic stenosis

In order to determine the reliability of a single arterial access technique for hemodynamic assessment of aortic stenosis, data obtained from this method was compared with that from dual arterial access in 13 patients. A 59 cm long, 8 Fr. Mullins Transseptal Sheath (MTS) was placed in the ascending aorta (AA) and a 5 Fr. pigtail catheter advanced through the MTS (using a hemostatic "Y" adapter) into the left ventricle for simultaneous pressure recordings. Another 5 Fr. pigtail catheter (PTC) was advanced in the AA from the contralateral femoral artery. Peak pressures, AA pressure-tracing characteristics, mean gradients, and the aortic valve area using tracings from the MTS and the PTC were compared. Peak pressures 120 +/- 8 vs. 119 +/- 8 mmHg (r = .998), "T" time .16 +/- .01 vs. .15 +/- .01 sec. (r = .913), "U" time .36 +/- .02 vs. .36 +/- .02 sec. (r = .983), mean gradients 38.4 +/- 6.1 vs. 39.6 +/- 6.9 mmHg (r = .990) and the AV area .78 +/- .08 vs. 79 +/- .08 cm2 (r = .994) were similar. Therefore, this single arterial technique provides data comparable to the traditional dual access system for hemodynamic assessment of aortic stenosis.

Effects of serosal anion composition on the permeability properties of rabbit urinary bladder

This study describes the effects of serosal Cl- and HCO3- substitution on transepithelial Na+ transport and basolateral membrane properties of the rabbit urinary bladder. Replacement of Cl- with NO3-, SCN-, and Br- had no effect on transepithelial Na+ transport or the basolateral membrane potential (Vbl). However, gluconate, isethionate, and cyclamate (anions that were shown previously to be not as permeable as Cl- through the basolateral membrane anion channel), decreased transepithelial Na+ transport and depolarized Vbl. Replacement of HCO3- also produced a decrease in transepithelial Na+ transport and a depolarization of Vbl. Utilizing conventional and K+-specific microelectrodes, we found the depolarization to be due to a reduction in basolateral K+ conductance. This depolarization was reversible only when Cl- was returned to the serosal solution, the normally permeant anion NO3- being unable to affect repolarization, suggesting that both the K+ and Cl- conductance are reduced during depolarization. A lag period of some 4 min preceded the repolarization of Vbl. The Na+-H+ exchange blocker amiloride prolonged the lag phase associated with repolarization, whereas niflumic acid, a Cl-(-)HCO3- exchange blocker (in red blood cells) reduced the magnitude of Vbl repolarization. Because of the possible involvement of the exchangers it is believed that the lag phase represents a volume-dependent and/or pH-dependent reactivation of the basolateral membrane conductances.

Use of ionophores in epithelia: characterizing membrane properties

In this chapter we have described the use of antibiotics for studying epithelial membrane resistances and permeabilities, as well as active and passive transport processes. We placed particular emphasis on sources of artifacts that could result in erroneous determination of any of the above parameters, as well as methods for assessing such artifacts (where possible). Although the number of possible artifacts seems large, it is not our intention to dissuade researchers from using this probe of epithelial function, but rather to point out how data might be incorrectly interpreted.

Characterization of a partially degraded Na+ channel from urinary tract epithelium

The mammalian urinary bladder contains in its apical membrane and cytoplasmic vesicles, a cation-selective channel or activating fragment which seems to partition between the apical membrane and the luminal (or vesicular space). To determine whether it is an activating fragment or whole channel, we first demonstrate that solution known to contain this moiety can be concentrated and when added back to the bladder causes a conductance increase, with a percent recovery of 139 +/- 25%. Next, we show that using tip-dip bilayer techniques (at 21 degrees C) and a patch-clamp recorder, the addition of concentrated solution resulted in the appearance of discrete current shots, consistent with the incorporation of a channel (as opposed to an activating fragment) into the bilayer. The residency time of the channel in the bilayer was best described by the sum of two exponentials, suggesting that the appearance of the channel involves an association of the channel with the membrane before insertion. The channel is cation selective and more conductive to K+ than Na+ (by a factor of 1.6). It has a linear I-V relationship, but a single-channel conductance that saturates as KCl concentration is raised. This saturation is best described by the Michaelis-Menten equation with a Km of 160 mM KCl and a Gmax of 20 pS. The kinetics of the channel are complex, showing at least two open and two closed states.(ABSTRACT TRUNCATED AT 250 WORDS)

Microtubule-associated protein MAP2 shares a microtubule binding motif with tau protein

The microtubule-associated protein MAP2 is a prominent large-sized component of purified brain microtubules that, like the 36- to 38-kilodalton tau proteins, bears antigenic determinants found in association with the neurofibrillary tangles of Alzheimer's disease. The complete sequence of mouse brain MAP2 was determined from a series of overlapping cloned complementary DNAs. The sequence of the carboxyl-terminal 185 amino acids is very similar (67 percent) to a corresponding region of tau protein, and includes a series of three imperfect repeats, each 18 amino acids long and separated by 13 or 14 amino acids. A subcloned fragment spanning the first two of the 18-amino acid repeats was expressed as a polypeptide by translation in vitro. This polypeptide copurified with microtubules through two successive cycles of polymerization and depolymerization, whereas a control polypeptide derived from the amino-terminal region of MAP2 completely failed to copurify. These data imply that the carboxyl-terminal domain containing the 18-amino acid repeats constitutes the microtubule binding site in MAP2. The occurrence of these repeats in tau protein suggests that these may be a general feature of microtubule binding proteins.

Applications of percutaneous transluminal coronary angioplasty in cardiac transplantation. Preliminary results in five patients

Atherosclerotic coronary artery disease is the major cause of late cardiac transplant failure secondary to silent ischemia and infarction. To increase the longevity of cardiac homografts, we performed percutaneous transluminal coronary angioplasty (PTCA) in five male patients (aged 45 +/- 7 years, mean +/- SEM); 17 lesions were dilated during eight procedures 83 +/- 11 months after cardiac transplant. PTCA was successful (greater than or equal to 20% change in vessel diameter) in 13 of 17 (76%) lesions (the degree of prePTCA stenosis was 84% +/- 3% vs. 40% +/- 4% postPTCA; p less than or equal to 0.01). Multiple PTCA procedures were performed for progressive coronary artery disease in two patients; in one patient, two procedures were 13 months apart, and, in the second patient, another three procedures were 2 and 6 months apart. Indications for PTCA included reversible thallium perfusion defects, segmental left ventricular wall-motion abnormalities, or both in the distribution of proximal coronary artery stenoses. No deterioration occurred in the four unsuccessful PTCA attempts (two patients with initial total occlusion, and two patients in whom the lesion could not be crossed with a guidewire). Noninvasive evidence of ischemia was improved immediately after PTCA in all cases. Three patients remain alive 5, 7, and 11 months, respectively, after PTCA without evidence of new ischemia. One patient died 39 months after his first PTCA, while another patient was retransplanted 8 months after the first PTCA. Thus, PTCA can be performed in cardiac transplant patients with proximal major vessel coronary artery disease and may prolong cardiac homograft function.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempted suicide in youth: its relationship to school achievement, educational goals, and socioeconomic status

Twenty-six suicide attempters, 9 to 18 years of age, were compared with 725 nonattempters on measures of school achievement, educational goals, socioeconomic status, and depression. As has been found in studies using clinical samples, suicide attempters in our community-based sample had significantly lower school achievement than nonattempters. The relationship between attempted suicide and low school achievement seemed to be explained by the effects of depression. Lower-SES youth tended to be more likely to attempt suicide than higher-SES youths. However, SES appeared to have little effect on the relationship between attempted suicide and school achievement. Results also suggest that children of mothers with low educational goals for them may be more at risk for attempted suicide than youths whose mothers have higher educational goals for their children.

Differential distribution of beta-tubulin isotypes in cerebellum

We describe the structure and expression of a mammalian beta-tubulin isotype (M beta 6) that is weakly expressed in testis but is abundant in developing brain, with transcripts declining to lower levels in the adult brain. The expression of M beta 6 was undetectable in any other mouse tissue examined. A serum specific for this isotype was prepared using a cloned fusion protein as immunogen. M beta 6 is one of five known beta-tubulin isotypes expressed in brain, and using the anti-M beta 6 serum along with sera, anti-M beta 2, anti-M beta 3/4 and anti-M beta 5, previously characterized, we have examined the pattern of expression of beta-tubulin isotypes in rat cerebellum. The isotypes each have characteristic cell-type specific patterns of localization in cerebellum. M beta 2, M beta 3/4 and M beta 5 are present in both neuronal and non-neuronal cells, but in contrast M beta 6 was only detectable in neurons in tissue sections and in dissociated cerebellar cell culture. The majority of sequence differences among the beta-tubulin isotypes lie at the carboxy terminus, the region of beta-tubulin involved in MAP binding. In the case of M beta 2 and M beta 6, the patterns of expression are similar or identical to the patterns of expression of MAP3 and MAP1A respectively. These results suggest that beta-tubulin isotypes may contribute to the determination of the specific association of MAPs with microtubules of diverse function. However, the strict subcellular segregation of other MAPs in brain may be determined by other factors.

Triple vessel coronary angioplasty: acute outcome and long-term results

Triple vessel coronary angioplasty, defined as angioplasty of one or more lesions in each of the three major coronary arteries (left anterior descending, left circumflex, right coronary artery) was performed in 50 (11%) of 469 patients who had angioplasty of multiple vessels. There were 32 men and 18 women with a mean age of 56 years. All 50 patients had severe three vessel coronary disease and represent approximately 5% of patients with three vessel disease who had revascularization in this institution; 8 (16%) had previous coronary bypass surgery, and 23 (46%) had previous myocardial infarction. Unstable angina was present in 33 patients (66%) and 96% had Canadian Heart Association class III or IV angina; mean left ventricular ejection fraction was 57 +/- 11%. Angioplasty was performed in 176 vessels (3.5 vessels per patient, range 3 to 6) and in 250 lesions (5 lesions per patient, range 3 to 9); angiographic success was achieved in 240 lesions (96%) and 166 vessels (94%). Success in all vessels attempted was achieved in 40 (80%) of the 50 patients. Clinical success (angiographic success associated with clinical improvement) was obtained in all 50 patients in whom triple vessel angioplasty was performed; none of them required urgent bypass surgery and 5 patients (10%) had a non-Q wave myocardial infarction. In four other patients triple vessel angioplasty was planned but not performed because of failure to dilate the primary vessel; urgent bypass surgery was required in one of these, who developed a Q wave infarction. Thus, overall clinical success in 54 patients was 93%; the incidence rate of myocardial infarction was 11%, and that of urgent surgery 1.8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Association between extent of coronary artery disease and ventricular premature beat frequency after myocardial infarction

Severe coronary artery disease (CAD) and frequent ventricular premature beats (VPBs) on ambulatory ECG monitoring in the late hospital phase after myocardial infarction are independent predictors of prognosis. To study the relationship between extent of CAD and VPB frequency, 128 consecutive (91 men, 37 women) patients surviving 6 days after myocardial infarction underwent 24-hour ECG, coronary angiography, and left ventriculography. CAD was graded as zero to one-, two-, and three-vessel (V), and also by a previously validated "jeopardy score" with 0 to 12 as grades of incremental CAD severity. Average VPB frequency was significantly correlated with CAD by V, CAD by jeopardy score, and by left ventricular ejection fraction (p less than 0.01 for all three). With the use of a multivariate ordinal logistic regression model, both VPB frequency and left ventricular ejection fraction were found to have independent association with CAD. The median VPB frequency was 1/hr, 0.6/hr, and 6/hr in zero to one-, two-, and three-V CAD, respectively (zero to one- and two-V CAD vs three-V CAD p less than 0.01, one-V CAD vs two-V CAD p = NS). In conclusion, frequent VPBs following myocardial infarction are associated with extensive CAD and are independent of left ventricular ejection fraction. Therefore, the prognostic value of frequent VPBs may be related to severe underlying ischemic disease.

Complex regulation and functional versatility of mammalian alpha- and beta-tubulin isotypes during the differentiation of testis and muscle cells

In the accompanying paper (Gu, W., S. A. Lewis, and N. J. Cowan. 1988. J. Cell Biol. 106: 2011-2022), we report the generation of three antisera, each of which uniquely recognizes a different mammalian alpha-tubulin isotype, plus a fourth antibody that distinguishes between microtubules containing the tyrosinated and nontyrosinated form of the only known mammalian alpha-tubulin gene product that lacks an encoded carboxy-terminal tyrosine residue. These sera, together with five sera we raised that distinguish among the known mammalian beta-tubulin isotypes, have been used to study patterns of tubulin isotype-specific expression in muscle and testis, two tissues in which characteristic developmental changes are accompanied by dramatic rearrangements in microtubule structures. As in the case of cells in culture, there is no evidence to suggest that there is subcellular sorting of different tubulin isotypes among different kinds of microtubule, even in a cell type (the developing spermatid) that simultaneously contains such functionally distinct structures as the manchette and the flagellum. On the other hand, the patterns of expression of the various tubulin isotypes show marked and distinctive differences in different cell types and, in at least one case, evidence is presented for regulation at the translational or posttranslational level. The significance of these observations is discussed in terms of the existence of the mammalian alpha- and beta-tubulin multigene families.

Generation of antisera that discriminate among mammalian alpha-tubulins: introduction of specialized isotypes into cultured cells results in their coassembly without disruption of normal microtubule function

To assay the functional significance of the multiple but closely related alpha-tubulin polypeptides that are expressed in mammalian cells, we generated three specific immune sera, each of which uniquely recognizes a distinct alpha-tubulin isotype. All three isotypes are expressed in a tissue-restricted manner: one (M alpha 3/7) only in mature testis, one (M alpha 4) mainly in muscle and brain, and the third (M alpha 6) in several tissues at a very low level. A fourth specific antiserum was also generated that distinguishes between the tyrosinated and nontyrosinated form of a single alpha-tubulin isotype. Because individual tubulin isotypes cannot be purified biochemically, these sera were raised using cloned fusion proteins purified from host Escherichia coli cells. To suppress the immune response to shared epitopes, animals were first rendered tolerant to fusion proteins encoding all but one of the known mammalian alpha-tubulin isotypes. Subsequent challenge with the remaining fusion protein then resulted in the elicitation of an immune response to unique epitopes. Three criteria were used to establish the specificity of the resulting sera: (a) their ability to discriminate among cloned fusion proteins representing all the known mammalian alpha-tubulin isotypes; (b) their ability to uniquely detect alpha-tubulin in whole extracts of tissues; and (c) their capacity to stain microtubules in fixed preparations of cells transfected with sequences encoding the corresponding isotype. The transfection experiments served to demonstrate (a) the coassembly of M alpha 3/7, M alpha 4, and M alpha 6 into both interphase and spindle microtubules in HeLa cells and NIH 3T3 cells, and (b) that the M alpha 4 isotype, which is unique among mammalian alpha-tubulins in that it lacks an encoded carboxy-terminal tyrosine residue, behaves like other alpha-tubulin isotypes with respect to the cycle of tyrosination/detyrosination that occurs in most cultured cells.

Nerve growth factor regulates both the phosphorylation and steady-state levels of microtubule-associated protein 1.2 (MAP1.2)

This study characterizes effects of nerve growth factor (NGF) on the steady-state level and phosphorylation of a high molecular mass microtubule-associated protein in PC12 rat pheochromocytoma cells. Past work showed that NGF significantly raises the relative levels of this phosphoprotein, designated MAP1.2, with a time course similar to that of neurite outgrowth. To study this in greater detail, MAP1.2 in PC12 cell lysates was resolved by SDS-PAGE in gels containing 3.25% acrylamide/4 M urea and identified by comigration with material immunoprecipitated from the lysates by MAP1 antibodies. Quantification by metabolic radiolabeling with [35S]methionine or by silver staining revealed a 3.0-3.5-fold increase in MAP1.2 levels relative to total cell protein after NGF treatment for 2 wk or longer. A partial increase was detectable after 3 d, but not after 2 h of NGF exposure. As measured by incorporation of [32P]phosphate, NGF had a dual effect on MAP1.2. Within 15 min to 2 h, NGF enhanced the incorporation of phosphate into MAP1.2 by two- to threefold relative to total cell phosphoproteins. This value slowly increased thereafter so that by 2 wk or more of NGF exposure, the average enhancement of phosphate incorporation per MAP1.2 molecule was over fourfold. The rapid action of NGF on MAP1.2 could not be mimicked by either epidermal growth factor, a permeant cAMP derivative, phorbol ester, or elevated K+, each of which alters phosphorylation of other PC12 cell proteins. SDS-PAGE revealed multiple forms of MAP1.2 which, based on the effects of alkaline phosphatase on their electrophoretic mobilities, differ, at least in part, in extent of phosphorylation. Before NGF treatment, most PC12 cell MAP1.2 is in more rapidly migrating, relatively poorly phosphorylated forms. After long-term NGF exposure, most is in more slowly migrating, more highly phosphorylated forms. The effects of NGF on the rapid phosphorylation of MAP1.2 and on the long-term large increase in highly phosphorylated MAP1.2 forms could play major functional roles in NGF-mediated neuronal differentiation. Such roles may include effects on microtubule assembly, stability, and cross-linking and, possibly for the rapid effects, nuclear signaling.

Copper, iron, zinc, and selenium dietary intake and status of Nepalese lactating women and their breast-fed infants

The dietary intake of copper, iron, zinc, and selenium of 26 Nepalese lactating mothers was estimated from chemical analysis of 24-h food and beverage composites. Fasting blood and milk samples were obtained from the mothers and blood samples were obtained from the infants. The Nepalese mothers consumed significantly more Cu, significantly less Fe and Se, and similar amounts of Zn as compared with American lactating women. Blood Fe status indices and plasma concentrations of Cu, Zn, and Se were lower in the Nepalese mothers than in the American mothers. These lower values may in part be related to the high neutral detergent fiber and phytate content of the Nepalese diet, which could make these minerals less available for absorption. The high exposure to infections in Nepal may also depress Fe status indices and plasma Zn concentrations. The lower dietary Se intake of the Nepalese mothers was reflected in lower milk concentrations.