The upregulation of Na+,K(+)-ATPase pump numbers in lymphocytes from the first-degree unaffected relatives of patients with manic depressive psychosis in response to in vitro lithium and sodium ethacrynate

Patients with manic depressive disorder (DSM-III-R bipolar disorder) have an abnormality of the Na+,K(+)-ATPase pumps in their lymphocytes: the pump numbers do not upregulate to stimulation with lithium and ethacrynate. We have now investigated the in vitro adaptive responses of lymphocyte Na+,K(+)-ATPase pumps in the first-degree unaffected relatives of patients with a clear history of manic depressive disorder. The lymphocytes of the healthy relatives upregulated their Na+,K(+)-ATPase pumps normally, suggesting that the abnormal response that we have previously observed in patients with the disorder reflects a complex relation between the biochemical phenotype and the development of clinical symptoms.

Overview of morphological changes in enamel organ cells associated with major events in amelogenesis

The formation and mineralization of enamel is controlled by epithelial cells of the enamel organ which undergo marked, and in some cases repetitive, alterations in cellular morphology as part of the developmental process. The most dramatic changes are seen in ameloblasts which reverse their secretory polarity during differentiation to allow for extracellular release of large amounts of proteins from plasma membrane surfaces that were originally the embryonic bases of the cells. Secreted enamel proteins at first do not accumulate in a layer but, in part, percolate into the developing predentin and subjacent odontoblast layer. Appositional growth of an enamel layer begins with mineralization of the dentin, and ameloblasts develop a complicated functional apex (Tome's processes) to direct release of matrix proteins, and perhaps proteinases, at interrod and rod growth sites. Once the full thickness of enamel is produced, some ameloblasts degenerate, and the surviving cells shorten in height and spread out at the enamel surface. They reform a basal lamina to cover the immature enamel, and continue producing small amounts of enamel proteins that pass through the basal lamina into the enamel. Ameloblasts also undergo cycles of modulation where apical invaginations enriched in Ca-ATPases and other enzymes are formed and shed on a repetitive basis (ruffle-ended/smooth-ended transitions). As this happens, apatetic crystals seeded earlier expand in volume by gradual layering of new mineral at the surfaces of the preformed crystals. Ameloblasts stop modulating when the crystals almost fill existing volume formerly occupied by protein and water.(ABSTRACT TRUNCATED AT 250 WORDS)

HTM 2022 medical gas pipeline systems

The new edition of HTM 2022 was published in April 1994 and supersedes HTM 22 which was last published in 1978. The new HTM was prepared following extensive consultation within the NHS and with contractors, manufacturers and other health care professionals. This article summarises the significant changes and developments which have been incorporated into the new HTM 2022. These developments are operational and technical and have considerable implications for Estates Managers. There are many significant changes in HTM 2022 for example Validation and Verification. It is strongly recommended that all staff who are in any way responsible for the operation of a medical gas pipeline system should attend an appropriate training or updating course.

Characterization and expression of an antifungal zeamatin-like protein (Zlp) gene from Zea mays

A cDNA clone encoding a basic thaumatin-like protein of Zea mays was recovered from a mid-development seed cDNA library. The gene, Zlp, encoded a protein that was nearly identical with maize zeamatin and alpha-amylase/trypsin inhibitor. Expression of Zlp mRNA was highest in the endosperm tissue of seed 4 weeks after pollination. Expression of zeamatin-like (ZLP) protein correlated with mRNA; also, a low basal level of ZLP expression in leaf was not appreciably induced by abiotic stresses. ZLP was expressed with its own signal peptide in insect cells and in transgenic Arabidopsis and tomato plants. ZLP was secreted in all three systems, with correct processing of the signal peptide. ZLP expressed in transgenic tomato was found to be partially subjected to a proteolytic cleavage after residue 180, by an unknown mechanism, to give a "nicked" isoform of ZLP. Purified ZLP from all three sources, as well as purified "nicked" ZLP from tomato, demonstrated fungal inhibition against Candida albicans and Trichoderma reesei, with marginal inhibition observed against Alternaria solani and Neurospora crassa.

A model of caregiving effectiveness for technologically dependent adults residing at home

Caregiver-care-receiver interactions unique to this model of caregiving effectiveness were tested longitudinally in a randomly drawn national sample of 111 caregivers. Path analyses results indicate that variables explain variance in caregiver and patient quality of life, patient condition, and technological side effects. These findings extend nursing knowledge related to caregiving motivation-to-help and mutual interactions and thus have implications for home care practice. Effective family caregiving of loved ones dependent on technology for survival can result in enhanced patient condition, return to work, normalization of family life, and for society a reduction in health care costs.

Protein synthesis elongation factor EF-1 alpha is essential for ubiquitin-dependent degradation of certain N alpha-acetylated proteins and may be substituted for by the bacterial elongation factor EF-Tu

Targeting of different cellular proteins for conjugation and subsequent degradation via the ubiquitin pathway involves diverse recognition signals and distinct enzymatic factors. A few proteins are recognized via their N-terminal amino acid residue and conjugated by a ubiquitin-protein ligase that recognizes this residue. Most substrates, including the N alpha-acetylated proteins that constitute the vast majority of cellular proteins, are targeted by different signals and are recognized by yet unknown ligases. We have previously shown that degradation of N-terminally blocked proteins requires a specific factor, designated FH, and that the factor acts along with the 26S protease complex to degrade ubiquitin-conjugated proteins. Here, we demonstrate that FH is the protein synthesis elongation factor EF-1 alpha. (a) Partial sequence analysis reveals 100% identity to EF-1 alpha. (b) Like EF-1 alpha, FH binds to immobilized GTP (or GDP) and can be purified in one step using the corresponding nucleotide for elution. (c) Guanine nucleotides that bind to EF-1 alpha protect the ubiquitin system-related activity of FH from heat inactivation, and nucleotides that do not bind do not exert this effect. (d) EF-Tu, the homologous bacterial elongation factor, can substitute for FH/EF-1 alpha in the proteolytic system. This last finding is of particular interest since the ubiquitin system has not been identified in prokaryotes. The activities of both EF-1 alpha and EF-Tu are strongly and specifically inhibited by ubiquitin-aldehyde, a specific inhibitor of ubiquitin isopeptidases. It appears, therefore, that EF-1 alpha may be involved in releasing ubiquitin from multiubiquitin chains, thus rendering the conjugates susceptible to the action of the 26S protease complex.

The influence of tape type and of skin preparation on the force required to dislodge angiocatheters

The study evaluated the effects of different techniques used to secure intravenous (i.v.) catheters. An angiocatheter attached to standard i.v. tubing was taped to human forearm using a standard taping method. A calibrated piezoelectric force transducer was attached to the i.v. tubing. The force applied along the longitudinal axis to pull out the taped catheter was measured and recorded on paper. Three tape types, Curity, Leukopor and Transpore, were evaluated alone, with benzoin skin pretreatment and with mastisol pretreatment. A randomized 3 x 3 block design with 20 replications per block was utilized, and a total of 180 pullout tests were performed on two adult volunteers. Without pretreatment, the forces required to dislodge catheters were (means +/- SEM) 46 +/- 2, 37 +/- 2 and 38 +/- 2 Newtons for Curity, Leukopor and Transpore tape, respectively. Corresponding values for mastisol pretreatment (64 +/- 1, 64 +/- 3 and 52 +/- 3 Newtons) were greater (P < 0.05) for each tape compared with benzoin (54 +/- 3, 53 +/- 2 and 40 +/- 2 Newtons) and no pretreatment. The most frequent failure mode for Transpore tape was by tape fracture, for Curity tape was by separation from the skin of tape and catheter as a single unit, and for Leukopor tape was by catheter separation while tape remained attached to skin (P < 0.001). The data suggest that the application of mastisol prior to taping i.v. catheters with Curity or Leukopor tape helps to minimize the risk of accidental dislodgement.

Rhabdomyoma of the larynx: a rare cause of stridor

Rhabdomyomas of the larynx are rare tumours. In the literature to date 18 cases have been reported. They usually present with slowly progressive symptoms typical of their benign nature. We present a case that has many atypical features for an 'adult' type rhabdomyoma and discuss the relevant associated literature.

Isolation of Escherichia coli synthesized recombinant eukaryotic proteins that contain epsilon-N-acetyllysine

Recombinant porcine (rpST) and bovine somatotropins (rbST) synthesized in Escherichia coli contain the amino acid, epsilon-N-acetyllysine. This amino acid was initially discovered in place of the normal lysine144 in a modified reversed-phase HPLC (RP-HPLC) species of rpST. Mass spectrometry and amino acid sequencing of a tryptic peptide isolated from this RP-HPLC purified protein were used to identify this altered residue as epsilon-N-acetyllysine. Ion-exchange chromatography was utilized to prepare low isoelectric point (pI) forms of rpST and rbST, which are enriched in epsilon-N-acetyllysine. Electrospray mass spectrometry demonstrated that the majority of the protein in these low pI fractions contained species 42 Da larger than normal. Immobilized pH gradient electrophoresis (IPG) of the ion-exchange purified low pI proteins was used to isolate several monoacetylated species of rpST and rbST. The location of the acetylated lysine in each IPG-purified protein was determined by tryptic peptide mapping and amino acid sequencing of the altered tryptic peptides. Amino acid analyses of enzymatic digests of rpST and rbST were also used to confirm the presence of epsilon-N-acetyllysine in these recombinant proteins. These data demonstrate that a significant portion of rpST and rbST produced in E. coli contain this unusual amino acid.

Purification and characterization of a novel species of ubiquitin-carrier protein, E2, that is involved in degradation of non-"N-end rule" protein substrates

Ubiquitin-carrier proteins (E2s, ubiquitin-conjugating enzymes, UBCs) participate in proteolysis by catalyzing transfer of activated ubiquitin to the protein substrates, which are bound to specific ubiquitin-protein ligases (E3s). Yeast UBC2 (RAD6) and the mammalian E2(14kDa) bind to the ligase that recognizes and is involved in the degradation of certain free amino-terminal substrates ("N-end rule" substrates). As such proteins are rather scarce, the role of these E2s in general proteolysis is probably limited. Here, we report the purification and characterization of a novel 18-kDa species of E2 from rabbit reticulocytes. Unlike most members of the E2 family, this enzyme does not adsorb to anion exchange resin in neutral pH, and it is purified from the unadsorbed material (Fraction 1). Thus, it is designated E2-F1. Like all members of the E2 family, it generates a thiol ester with ubiquitin that serves as an intermediate in the conjugation reaction. Sequence analysis revealed a significant homology to many known species of E2s. The enzyme generates multiply ubiquitinated proteins in the presence of an E3 that has not been characterized yet. Most importantly, the ubiquitination via this E2 leads to the degradation of certain non-"N-end rule" substrates such as glyceraldehyde-3-phosphate dehydrogenase (Val at the NH2 terminus) and to the ubiquitination and degradation of certain N-alpha-acetylated proteins such as histone H2A, actin, and alpha-crystallin. The enzyme is also involved in the conjugation and degradation of the tumor suppressor protein p53.

Order and specificity of the Plasmodium falciparum hemoglobin degradation pathway

The human malaria parasite, Plasmodium falciparum, degrades nearly all its host cell hemoglobin during a short segment of its intraerythrocytic development. This massive catabolic process occurs in an acidic organelle, the digestive vacuole. Aspartic and cysteine proteases have been implicated in this pathway. We have isolated three vacuolar proteases that account for most of the globin-degrading activity of the digestive vacuole. One is the previously described aspartic hemoglobinase that initiates hemoglobin degradation. A second aspartic protease is capable of cleaving hemoglobin with an overlapping specificity, but seems to prefer acid-denatured globin. The third is a cysteine protease that does not recognize native hemoglobin but readily cleaves denatured globin. It is synergistic with the aspartic hemoglobinase, both by in vitro assay of hemoglobin degradation, and by isobologram analysis of protease inhibitor-treated parasites in culture. The cysteine protease is highly sensitive to chloroquine-heme complex, suggesting a possible mechanism of 4-aminoquinoline antimalarial action. The data suggest an ordered pathway of hemoglobin catabolism that presents an excellent target for chemotherapy.

Waiting time after non-depolarizing relaxants alter muscle fasciculation response to succinylcholine

The purpose of the study was to determine the effect of nondepolarizing muscle relaxants and waiting time on muscle fasciculations after succinylcholine in anaesthetized patients. Adult men and women, 60-80 kg, received pretreatment doses of atracurium 5 mg (n = 160), pancuronium 1 mg (n = 123), d-tubocurarine 3 mg (n = 97), or vecuronium 1 mg (n = 62). Waiting times between pretreatment and succinylcholine, 100 mg, ranged between 0.6 and 5 min. Data points (presence or absence of fasciculations and waiting time) were entered for each patient. Waiting time response curves were obtained between the logit transformation of the probability of no fasciculations and the log waiting time for each drug. Statistical differences between wait time response curves were determined by non-overlapping of the associated 95% confidence intervals. The frequency of muscle fasciculations was reduced with increased waiting time for all nondepolarizers tested. Following wait times of three, four and five minutes, the probability of not fasciculating was greatest with d-tubocurarine (90, 97 and 99%, respectively) and atracurium (89, 93 and 96%). Corresponding values for pancuronium were 70, 82 and 88% and for vecuronium were 74, 82 and 86%. Waiting times to prevent fasciculations in 80% and 90% of patients were shorter with d-tubocurarine (2.46 and 3.02 min, respectively) or atracurium (2.16 and 3.24 min) than pancuronium (3.77 and 5.35 min) or vecuronium (3.73 and 6.36 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Caregiver learning needs and reactions to managing home mechanical ventilation

OBJECTIVE

To identify caregivers' learning needs and reactions to providing care for adult patients receiving mechanical ventilation in the home. This report originated from a study that was undertaken to describe family function and reactions of family members.

DESIGN

Prospective, descriptive.

SETTING

Data collected at clients' homes in a midwestern city.

SUBJECTS

Twenty caregivers and adult patients who are dependent on mechanical ventilation at home.

INSTRUMENTS

Patients and their caregivers completed family coping and family function instruments. Caregivers also completed a Learning Needs Checklist and a caregiving inventory.

RESULTS

The results indicate that caregivers, all relatives, provided an average of 7.3 hours per day direct care with little assistance from extended family or professionals. More disrupted schedules, financial strain, increased burden, and negative reaction to caregiving was associated with increasing ventilator hours per day. Family function was perceived as satisfactory by both patients and caregivers. Survival knowledge and skills were being taught, but additional information was needed by caregivers. There were no differences by gender in perceived learning needs, family function, or tasks of daily caregiving.

CONCLUSIONS

Preferences for types of information suggest the use of a three-phase teaching program that should be sensitive to individual learning needs. A variety of coping strategies were used by families to manage home mechanical ventilation including problem-solving and mobilizing help from friends, extended family, community, or church.

Synaptic transmission in a diffusion model for neural activity

Equations for a diffusion neuronal model describing the production of nerve impulses have been derived for the case in which the noisy depolarizations of the membrane potential are restricted by the reversal potentials. Identifying neuron firing intervals with the first-passage-time distribution for the associated process allows us to compute the interspike interval statistics and relate them to the parameters characterizing the neuronal input. Methods for approximation of the first two moments of the interspike intervals are proposed. The analytical results are numerically illustrated and simultaneous computer simulations were performed for the same purpose. A comparison of the achieved results is made with those from other diffusion models or the models with discontinuous trajectories. The model is proposed mainly as an alternative to the Ornstein-Uhlenbeck neuronal model.

Characterization of human uroguanylin: a member of the guanylin peptide family

Guanylin, a peptide homologue of the bacterial heat-stable enterotoxins (ST), is an endogenous activator of guanylate cyclase C (GC-C). We have initiated a search for other members of the guanylin peptide family and in the current study describe a "guanylin-like peptide" from human urine. Bioactivity was monitored by determining the effect of urine extracts on T84 cell guanosine 3',5'-cyclic monophosphate (cGMP) levels. Purification yielded two bioactive peaks of peptides that, when sequenced by NH2-terminal analysis, possessed 15 and 16 amino acids. The sequence of the smaller peptide represented an NH2-terminal truncation of the larger peptide. We have termed the larger peptide human uroguanylin; it has the following amino acid sequence: NDDCELCVNVACTGCL. Human uroguanylin shares amino acid sequence homology with guanylin and ST. Synthetic uroguanylin increased cGMP levels in T84 cells, competed with 125I-labeled ST for receptors, and stimulated Cl- secretion as reflected by an increased short-circuit current. Thus we report the isolation from human urine of a unique peptide, uroguanylin, that behaves in a manner similar to guanylin and appears to be a new member of this peptide family.

Exacerbation of asthma after pyridostigmine during Operation Desert Storm

Pyridostigmine was first used extensively during Operation Desert Storm for prophylaxis against the effects of nerve agents. After initial reports of asthma exacerbations following its use, we gave 10 asthmatic and 6 non-asthmatic soldiers a 30-mg dose of pyridostigmine. We found no changes in forced vital capacity in any of the soldiers, but observed exacerbation of asthma symptoms in seven of the asthmatics. Severity of the exacerbation correlated best with severity of asthma in the desert and inversely with body weight. The irritant effect of the dust may predispose asthmatics to worsen after pyridostigmine, an effect not seen in the laboratory.

Uroguanylin: structure and activity of a second endogenous peptide that stimulates intestinal guanylate cyclase

The intestinal hormone guanylin and bacterial heat-stable enterotoxins (STs) are members of a peptide family that activates intestinal membrane guanylate cyclase. Two different peptides that activate the human intestinal T84 cell guanylate cyclase have been purified from urine and intestinal mucosa of opossums (Didelphis virginiana). The highly acidic peptide, QEDCELCINVACTGC, was named uroguanylin because it was isolated from urine and shares 53% identity with guanylin. A second peptide, SHTCEICAFAACAGC, was purified from urine and intestinal mucosa. This alanine-rich peptide was 47% identical to uroguanylin and 73% identical to human guanylin, suggesting that it may be an opossum homologue of guanylin. Synthetic uroguanylin-(2-15) (i.e., EDCELCINVACTGC) was 10-fold more potent than synthetic rat guanylin, but both peptides were less potent than Escherichia coli ST in the T84 cell cGMP bioassay. Uroguanylin-(2-15) and guanylin inhibited 125I-ST binding to T84 cell receptors in competitive radioligand binding assays. Transepithelial Cl- secretion was stimulated by 1 microM uroguanylin, indicated by an increase in the short circuit current of T84 cells. Thus, uroguanylin is another paracrine hormone in the emerging peptide family that activates intestinal membrane guanylate cyclase. The second peptide may be the opossum form of guanylin, or perhaps, it is still another member of this peptide family. The presence of uroguanylin and guanylin in urine and receptors in proximal tubules suggests that these peptides may also originate from renal tissue and may regulate kidney function.

Quality of life in long-term total parenteral nutrition patients and their family caregivers

The purpose of this study was to identify individual and family variables associated with patient and caregiver quality of life. Perceived quality of life has been associated with improved outcomes and compliance. Methods included telephone interviews of 178 families, randomly selected from academic, hospital, and infusion agencies across the United States, with 116 follow-up questionnaires returned. Patients had varied bowel disorders requiring total parenteral nutrition for an average of 4.6 years. Patients were an average of 52.0 years old; caregivers averaged 52.5 years of age. Coded interview data indicated that caregivers assist patients daily (for a mean of 4.2 hours) and provide emotional support. Problems such as loss of friends, loss of employment, and depression were reported in two thirds of the families. Overall low quality of life was associated with length of time on total parenteral nutrition, fewer family coping skills, and inability to get along on income, whereas higher quality of life was associated with higher self-esteem and quality in the relationship. Preparing families for potential social problems or situations related to depression while also enhancing financial assistance, self-esteem, quality in the relationship, and coping skills may increase both patient and caregiver quality of life.

Effects of chronic fluoride exposure on morphometric parameters defining the stages of amelogenesis and ameloblast modulation in rat incisors

The response of ameloblasts to long-term (6 weeks) exposure to 100 ppm fluoride was examined in continuously erupting mandibular incisors of female Sprague-Dawley rats as compared to control rats receiving a similar diet (Teklad L-356) but no sodium fluoride in their drinking water. After treatment, animals from both groups were perfused intravascularly with glutaraldehyde, and the incisors were removed and processed for light microscope morphometric analyses directly from 1 microns thick Epon sections. Other animals were injected intravenously with calcein (green fluorescence) followed 4 hours later by xylenol orange (red fluorescence) in order to reveal smooth-ended ameloblast modulation bands and thereby allow quantification of parameters related to the creation and movement of modulation waves within the maturation zone of these teeth. The results indicated that rat incisors expressed four major changes in normal amelogenesis which could be attributed to the chronic fluoride treatment. First, ameloblasts produced a thinner than normal enamel layer by the time they completed the secretory stage and entered the maturation stage of amelogenesis. Second, enamel organ cells within the maturation zone, especially those from the papillary layer, were shorter in height than normal. Third, ameloblasts related to maturing enamel in areas where it was partially soluble and/or fully soluble in EDTA modulated at a rate that was much slower than normal. In some locations ameloblasts remained ruffle-ended for as much as 30% longer than normal per cycle. This upset the usual pattern such that fewer total modulation cycles were completed per unit time by these ameloblasts. Fourth, enamel proteins were lost from the maturing enamel layer at a rate that was about 40% slower than normal. The data suggested that ameloblasts detected the delay in the extracellular breakdown and/or loss of enamel proteins and they responded by remaining ruffle-ended for longer intervals than usual (positive feedback).

Isolation and characterization of porcine somatotropin containing a succinimide residue in place of aspartate129

Aspartate129 in porcine somatotropin was converted into a cyclic imide residue (succinimide) under acidic solution conditions. Reversed-phase high performance liquid chromatography was utilized to isolate and quantitate this altered species, which accounted for approximately 30% of the total protein. The molecular mass of this modified species was determined by electrospray mass spectrometry to be 18 Da less than normal porcine somatotropin, indicative of a loss of 1 H2O molecule. Tryptic peptide mapping demonstrated that the peptide composed of residues 126-133 was altered in this modified protein. Amino acid analysis, amino acid sequencing, mass spectrometry, and capillary zone electrophoresis were used to demonstrate that aspartate129 in this peptide had been converted into a succinimide residue. Further confirmation that this peptide contained a succinimide was obtained by hydrolyzing the modified peptide at pH 9.0, which yielded both the aspartate and isoaspartate peptides.

Responsibilities and reactions of family caregivers of patients dependent on total parenteral nutrition at home

This prospective study assessed the caregiving responsibilities and reactions of family members who provide home care to a relative who is dependent on total parenteral nutrition (TPN). A short, semistructured interview based on the Roy adaptation model was used to gather data about the caregiving experiences of 20 relatives of adult TPN-dependent patients. Data were content analyzed, and frequently occurring themes identified. Results indicated that altered family responsibilities as well as negative and positive psychologic reactions to caregiving do occur. The interviews suggested that caregivers master TPN technology but make little use of assistance from extended family or professionals. Although depression and fatigue were reported as common, these family members felt capable and successful in their caregiving roles. Further longitudinal research with larger samples should allow for comparison of caregivers on demographic differences, stress, and other variables pertinent to managing complex home care.

Prevention of hypoxemia during lumbar puncture in infancy with preoxygenation

Hypoxemia has previously been reported during lumbar puncture (LP) in infancy. The purpose of this study was to determine whether preoxygenation before the LP would reduce hypoxemia during the procedure in infants. Twenty-one infants (one to 15 weeks of age) undergoing LP for evaluation of possible sepsis were randomly assigned to the control group (12) or treatment group (9). The treatment group was preoxygenated breathing oxygen (FiO2 = 1.0) spontaneously via snug face mask for three minutes prior to being positioned for the LP. The control group spontaneously breathed room air during this interval. Oxyhemoglobin saturation was measured prior to, and continuously during, the LP with pulse oximetry. The groups were comparable in age, resting respiratory rate, baseline saturation, and duration of the procedure. The treatment group developed significantly less desaturation during the procedure than the control group (P < 0.05). We conclude that preoxygenation prior to LP prevents most of the hypoxemia resulting from the procedure in infants.

Identification of the sites of phosphorylation in insulin-like growth factor binding protein-1. Regulation of its affinity by phosphorylation of serine 101

Serine phosphorylation of insulin-like growth factor binding protein-1 (IGFBP-1) has been shown to alter its affinity for the insulin-like growth factors (IGF-I and IGF-II) and to modify its capacity to modulate cellular responses to the IGFs. Because of this, we determined the sites of serine phosphorylation. Purification of 32P-labeled IGFBP-1 was followed by digestion with trypsin and endoproteinase Glu-C and radiosequencing of labeled peptides. Three serines were found to be phosphorylated, with Ser101, Ser119, and Ser169 containing 70%, 5%, and 25% of the incorporated 32P, respectively. A mutated IGFBP-1, substituting alanine for serine at positions 98 and 101, was expressed in CHO cells. On nondenaturing gels, the wild type protein migrated as five isoforms (one non-phosphorylated and four phosphorylated). However, in the mutated protein, the most rapidly migrating band (a phosphorylated form) was not present. The cells containing the mutated cDNA incorporated 60% less 32P into immunoprecipitable IGFBP-1. The mutated protein had a 3-fold reduction in affinity for IGF-I compared to the wild type protein. We conclude that Ser101 represents the major site of phosphorylation containing 63% of the total 32P incorporated and that phosphorylation of Ser101 is important for maintenance of high affinity binding for this growth factor.

Atrial septal lipomatous hypertrophy and ischemic heart disease: an unusual presentation

Lipomatous hypertrophy of the interatrial septum consists of the abnormal accumulation of fatty tissue. We report a patient with unsuspected massive lipomatous hypertrophy of the interatrial septum scheduled to undergo coronary artery surgery. This patient had experienced atrial arrhythmias and obstructive symptoms preoperatively that were ascribed to her coronary artery disease (CAD). The perioperative anesthetic and surgical management of patients with lipomatous hypertrophy of the interatrial septum and CAD is discussed.

High-level production of active HIV-1 protease in Escherichia coli

High levels of active HIV-1 protease (PR) were produced in Escherichia coli, amounting to 8-10% of total cell protein. High production levels were achieved by altering the following parameters: (1) codon preference of the coding region, (2) A+T-richness at the 5' end of the coding region, and (3) promoter. To circumvent the toxicity of HIV-1 PR in E. coli, the gene was expressed as a fusion protein with two different proteolytic autocleavage sequences. In both the cases, the fusion protein could be cleaved in vivo to give an active molecule with the native sequence at the N terminus.

Isolation and characterization of a 25 kDa antifungal protein from flax seeds

We have purified a 25 kDa protein from flax seeds to homogeneity by polyethyleneimine precipitation, ammonium sulfate precipitation, chitin extraction, Mono S cation exchange and C18 reversed phase column chromatographies. The purified protein strongly inhibited the growth of the agronomically important pathogen Alternaria solani, the causative agent of tomato early blight and in synergy with nikkomycin Z strongly inhibited the human pathogen Candida albicans. Amino terminal sequence analysis of the purified protein indicated that it has a high degree of homology to other reported pathogenesis-related antifungal proteins.

Immunolocalization of enamel proteins during amelogenesis in the cat

Amelogenesis in the cat has been suggested to closely resemble enamel formation in human teeth. In order to further characterize the sequence of events leading to enamel formation in the cat, the expression and distribution of enamel proteins throughout amelogenesis were examined by postembedding immunocytochemistry using an antibody to mouse amelogenins and the high resolution protein A-gold technique. Enamel proteins were first immunodetected in ameloblasts and in the extracellular matrix during the presecretory stage. Secretory stage ameloblasts showed the most intense cellular reactivity. In these cells, protein synthetic organelles, secretory granules, and large lysosome-like structures were all intensely labeled. Extracellularly, numerous gold particles were observed over enamel and over patches of material found at the baso-lateral surfaces of these ameloblasts. During the early maturation stage, the protein synthetic organelles and secretory granules of ameloblasts still showed some immunoreactivity, although the most conspicuous labeling at this later stage was found over enamel and over material present among the extensive apical membrane infoldings of ruffle-ended ameloblasts. Qualitative analysis of lysosome-like elements in ameloblasts suggested that their frequency and immunoreactivity in the maturation stage were relatively lower than in the secretory stage, where some groups of cells often showed numerous large labeled structures. The enamel matrix was intensely labeled at all stages; however, cervical-occlusal and surface-depth gradients were readily apparent by conventional staining and by quantitative analysis of immunolabeling in the late secretory and early maturation stages. These data suggest that the cellular and extracellular distribution of enamel proteins in the cat is generally similar to that reported in other species, although some particularities were observed, perhaps reflecting variation in the timing of developmental parameters.

A severe, unusual reaction to trimethoprim-sulfamethoxazole in patients infected with human immunodeficiency virus

The clinical features of three patients with a life-threatening reaction to trimethoprim-sulfamethoxazole (TMP-SMZ) are presented along with seven other cases from the literature. All patients developed sudden fever and hypotension immediately after the administration of TMP-SMZ; usually this reaction occurred within approximately 2 weeks of completion of a previous course of the drug. All but one patient had a rash. Most patients were hypoxemic and developed diffuse pulmonary infiltrates. All patients responded rapidly to supportive care, while bacterial cultures remained negative. The presence, absence, or character of previous adverse reactions to TMP-SMZ did not predict subsequent severe reactions. Although its mechanism remains unclear, this reaction has features of both IgE-mediated anaphylaxis and cytokine (tumor necrosis factor)-mediated effects. We advise extreme caution, with close observation, when this drug is first readministered to patients who have experienced any TMP-SMZ-associated toxicity within the previous 6-8 weeks.

Antifungal proteins from plants. Purification, molecular cloning, and antifungal properties of chitinases from maize seed

We have purified two 28-kDa chitinases, designated Chitinase A (Chit A) and Chitinase B (Chit B), from maize seeds to homogeneity and isolated cDNA clones encoding these two enzymes using an oligonucleotide probe based on an amino acid sequence of a peptide derived from Chit A. Although these two enzymes share 87% homology in their amino acid sequences, which were deduced from the nucleotide sequences of the isolated cDNA clones, they are significantly different in their biochemical and in vitro antifungal activities. When tested in vitro for antifungal activity against the growth of Trichoderma reesei, Alternaria solani, and Fusarium oxysporum, Chit A showed greater antifungal activity than Chit B. The specific activity of Chit A was determined to be 3-fold higher than that of Chit B. Chit A also had a 10-fold lower binding constant (Kd) against the substrate analogue N,N',N'',N'''-tetraacetyl chitotetrose than Chit B, indicating that the two enzyme may differ in their affinities for binding to the substrate chitin. Comparison of the amino acid sequences of maize seed chitinases with those of previously published chitinases from monocot and dicot plants indicates that maize seed chitinases have diverged significantly from other chitinases.

Guanylin: an endogenous activator of intestinal guanylate cyclase

Intestinal guanylate cyclase mediates the action of the heat-stable enterotoxin to cause a decrease in intestinal fluid absorption and to increase chloride secretion, ultimately causing diarrhea. An endogenous ligand that acts on this guanylate cyclase has not previously been found. To search for a potential endogenous ligand, we utilized T84 cells, a human colon carcinoma-derived cell line, in culture as a bioassay. This cell line selectively responds to the toxin in a very sensitive manner with an increase in intracellular cyclic GMP. In the present study, we describe the purification and structure of a peptide from rat jejunum that activates this enzyme. This peptide, which we have termed guanylin, is composed of 15 amino acids and has the following amino acid sequence, PNTCEICAYAACTGC, as determined by automated Edman degradation sequence analysis and electrospray mass spectrometry. Analysis of the amino acid sequence of this peptide reveals a high degree of homology with heat-stable enterotoxins. Solid-phase synthesis of this peptide confirmed that it stimulates increases in T84 cyclic GMP levels. Guanylin required oxidation for expression of bioactivity and subsequent reduction of the oxidized peptide eliminated the effect on cyclic GMP, indicating a requirement for cysteine disulfide bond formation. Synthetic guanylin also displaces heat-stable enterotoxin binding to cultured T84 cells. Based on these data, we propose that guanylin is an activator of intestinal guanylate cyclase and that it stimulates this enzyme through the same receptor binding region as the heat-stable enterotoxins.

OSHA's final rule on occupational exposure to bloodborne pathogens

This report is intended as a brief review of some of the key points of the new OSHA rule. It should not be used in place of the complete rule, and you should contact your legal advisor with any questions about interpretations of the rule. Because circumstances of occupational exposure vary among employers, it is advisable that employers be thoroughly acquainted with all requirements of the rule. The preamble to the rule, starting on page 64004 of the December 6, 1991 Federal Register, may provide helpful background information for understanding specific provisions of the rule.

Identification of an essential tyrosine residue in the catalytic site of a chitinase isolated from Zea mays that is selectively modified during inactivation with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide

Chitinase isolated from Zea mays seeds is inactivated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) in the absence of exogenous nucleophiles. Oligomers of N-acetylglucosamine,N,N',N",N"'-tetra-N-acetylchitotetraose (GlcNAc4), and to a lesser extent, N,N',N"-tri-N-acetylchitotriose (GlcNAc3) and N,N'-di-N-acetylchitobiose (GlcNAc2) provide partial protection against inactivation by the reagent. An examination of the concentration dependence of the protection afforded by GlcNAc4 revealed direct competition between the substrate analog and the reagent for the same binding sites on the enzyme. Isolation and Edman degradation of a "new" tryptic fragment, observed after inactivation of chitinase with EDC, revealed the sequence G-P-L-Q-I-S-W-N-*-N-Y-G-P-A-G-R, where the asterisk represents a cycle in which no amino acid was detected, presumably as a consequence of derivatization with EDC. In basic chitinases from dicotyledonous plants such as Arabidopsis thaliana, Phaseolis vulgaris (bean), Nicotiana tabacum (tobacco), and Solanum tuberosum (potato), as well as in the chitinase isolated from the monocotyledonous plant Hordeum vulgare (barley), this position is invariably occupied by a tyrosine. However, in the Oryza sativa (rice) basic chitinase, this position is occupied by a phenylalanine. The following additional evidence supports identification of this residue as tyrosine in Z. mays chitinase. (a) Inactivation of chitinase with EDC is reversible by treatment with hydroxylamine. (b) Liquid secondary ion mass spectrometric analysis of the isolated derivatized peptide revealed the presence of a molecular ion with a mass to charge ratio consistent with the peptide containing a derivatized tyrosine residue. These results provide evidence for an essential tyrosine residue at or near the catalytic site of chitinase that is selectively modified during inactivation with EDC.

A note on neuronal firing and input variability

The Ornstein-Uhlenbeck process with a constant forcing function has often been used as a model for the subthreshold membrane potential of a neuron. The mean, variance and coefficient of variation of the first passage time to a constant threshold are examined for this model in the limit of small synaptic noise and low thresholds. A comparison is made between the asymptotic results of Wan & Tuckwell, who used perturbation analysis, and several computationally simpler approximation methods. A generalization of Stein's method gives an overestimate of the mean interval while an approximation by a Wiener process with linear drift gives an underestimate of the mean interval. These bounds are simple to calculate and can be used as a prelude to a more detailed perturbation analysis.

Effects of afterhyperpolarization on neuronal firing

Stein's model for a neuron is studied. This model is modified to take into account the effects of afterhyperpolarization on the neuronal firing. The relative refractory phase, following the absolute one, is modelled by a time-increasing amplitude of postsynaptic potentials and it is also incorporated into the model. Besides the simulation of the model, some theoretical results and approximation methods are derived. Afterhyperpolarization tends to preserve the linearity of the frequency transfer characteristic and it has a limited effect on the moments of the interspike intervals in general. The main effects are seen at high firing rates and in the removal of short intervals in the interspike interval histogram.

Correlated biochemical and radioautographic studies of protein turnover in developing rat incisor enamel following pulse-chase labeling with L-[35S]- and L-[methyl-3H]-methionine

The movement of proteins into and out of enamel was followed over time using a highly sensitive microprecipitation technique to quantify the amount of TCA-insoluble radioactivity present within small pieces of freeze-dried enamel and cells (enamel organ) dissected from the mandibular incisors of rats injected with L-[35S]-methionine. Conventional image processing techniques were also used to estimate the number of silver grains over enamel and cells in radioautographs of mandibular incisors from rats similarly injected with L-[methyl-3H]-methionine. Data from both techniques indicated that the average half-life for labeled proteins secreted into enamel was about 8.9 days. Typically, radioactive proteins accumulated in increasing amounts for 8 hours after which they were lost slowly up to 4 days and more rapidly thereafter when enamel formed during the secretory stage underwent maturation. The half-life for radioactive proteins in cells was only about 20.7 hours. No significant accumulation of radioactivity could be detected in the TCA-soluble or TCA-insoluble fractions of cells as enamel development proceeded. Results from this study suggest that radioautographs provide an accurate estimate of changes occurring to proteins in enamel and cells except at early time intervals (less than 1 hour) when a high percentage of total radioactivity is present within the TCA-soluble fraction of cells.

Technological dependency: a preliminary model and pilot of home total parenteral nutrition

As hospital costs increase and durations of hospital stays decrease, clients are being discharged to home care in more acute states and often with demands for high technology therapy. To assist in understanding the experiences families face in adapting to either short- or long-term dependence on technology, a model was developed from literature and research review. The literature review suggested that self-care practices affected each of the family members' adaptation. The model was developed to indicate self-care issues and problems impacting adaptation to high technology at home. A pilot study was conducted to determine if interviews and questionnaires would collect data necessary to test the model. This article describes the pilot study results. Data indicated that relationships and role changes did occur after the family became technologically dependent. Also, although depression and anxiety were common responses, the family members felt capable and successful in their caregiving roles.

Characterization of the genome of rice tungro bacilliform virus: comparison with Commelina yellow mottle virus and caulimoviruses

Rice tungro disease is caused by an infection of two different viruses, rice tungro spherical virus (a (+) sense RNA virus) and rice tungro bacilliform virus (RTBV) with a genome of circular double-stranded DNA. The genome of an RTBV isolate from the Philippines was cloned, sequenced, and found to be 8000 bp in length. It contains four open reading frames (ORFs) on a single strand, with ORF 1 having an internal termination codon (TAA). The 5' and 3' ends of a polyadenylated viral RNA transcript, of genome length, were mapped by primer extension and cDNA sequence analysis, respectively. The transcript is terminally redundant by 265-268 nucleotides. Purified virus particles contain two major proteins with molecular masses of 37 and 33 kDa, although only the 37-kDa protein was detected in the infected rice tissues. The N-terminal amino acid sequence of the 33-kDa protein was determined and its coding region was identified on the RTBV genome. The identity of the coat protein gene was further confirmed by expressing a region of the genome in Escherichia coli, the products of which reacted with anti-RTBV antibody. The unusually long ORF 3 of RTBV is predicted to encode a polyprotein of 194.1 kDa that includes: the coat protein(s), viral proteinase, reverse transcriptase, and ribonuclease H. The sections of the polyprotein show varying degrees of similarity to the counterparts of Commelina yellow mottle virus (a member of the proposed badnavirus group) and caulimoviruses. The functions of the other three ORFs are unknown.

Hemophagocytic syndrome: a cause of pancytopenia in human ehrlichiosis

A 67-year-old white man with human ehrlichiosis infection complicated by pancytopenia, hemophagocytic syndrome, disseminated intravascular coagulopathy and septic shock is presented. The patient had been on a three-week camping trip to California, Colorado, Utah, and New Mexico. The diagnosis of human ehrlichiosis was confirmed by sixteen-fold rise in antibody titer to Ehrlichia canis, and supported by the characteristic cytoplasmic inclusions. Human ehrlichiosis should be considered in the differential diagnosis in patients with fever and cytopenia associated with hemophagocytosis. Pancytopenia associated with ehrlichiosis is transient; however, it may be severe, and appears to be associated with destruction of normal blood elements.

Secretion of Active Bovine Somatotropin in Escherichia coli

We have expressed a chimeric protein, comprising the LamB secretion signal sequence fused to mature bovine somatotropin (bST), in Escherichia coli. Plasmid constructs with the recA promoter showed significant protein accumulation prior to induction and cell lysis occurred after induction. In contrast, the lacUV5 promoter was tightly regulated. With the lacUV5 promoter, temperature and inducer concentration had significant effects on the total amount of recombinant protein produced and the fraction processed to mature bST. Quantitation of bST from shake flask cultures showed that 1-2 micrograms/ml/OD550 could be released from the periplasm by osmotic shock. N-terminal sequence analysis of the purified protein indicated that the majority of the secreted bST was correctly processed. The bST present in the osmotic shock fraction was judged to be correctly folded by comigration with oxidized methionyl-bST standard on a non-reducing polyacrylamide gel and activity in a bovine liver radioreceptor assay. These results provide a rapid method to produce bST for use in structure-function studies.

Non-ketotic hyperglycinaemia in a neonate. A case report

Non-ketotic hyperglycinaemia was diagnosed in a newborn infant presenting with lethargy, apnoea, hiccoughs and myoclonic seizures. The typical findings of raised cerebrospinal fluid:plasma glycine ratio, a burst suppression pattern on electro-encephalography, hypodense areas seen on computed tomography and lack of acidosis, ketosis and serum organic acid abnormality confirmed the diagnosis. Prenatal diagnosis by investigating the glycine cleavage enzyme system from a chorionic villus sample is not yet available.

Adaptation in families with a member requiring mechanical ventilation at home

Current health care trends indicate that ventilator-dependent patients increasingly will be discharged to home after shorter hospitalizations. The purpose of this study was to determine how care givers adapt to having ventilator-dependent adults at home. Twenty families were interviewed in their homes by using an eight-question semistructured interview guide. The Roy model was used as a framework to analyze these data. Two instruments, the Family Coping Scale (F-COPES) and the Family APGAR, were administered to measure family coping and function. Patients, aged 18 to 74 years, required 24-hour (n = 9), 12- to 15-hour (n = 5), or 8- to 12-hour (n = 6) home ventilatory support and had neuromuscular or trauma-related diagnoses. Months receiving ventilation ranged from 2 to 312. Care givers, aged 20 to 74 years, were all relatives. Six care givers reported using support services outside their extended family. F-COPES scores fell within national norms whether the patient required 24-hour or less ventilation. Family APGAR results revealed satisfaction with overall family function although scores decreased over time. Interview data indicated that essential knowledge and skills are taught but additional information is desired. Both positive and negative responses to care giving were identified, with the majority of responses being concerned with role mastery, self-concept, and dependency issues. Positive themes in the interviews reflected confidence in ventilator care, satisfaction with the decision to care for their family member at home, and improved quality of life. Negative themes in the interviews reflected the burden of care giving, the dependence of the patient on the care giver, resentment, and hopelessness.(ABSTRACT TRUNCATED AT 250 WORDS)