Potentiation by thyroxine of interferon-gamma-induced antiviral state requires PKA and PKC activities

Added to HeLa cells previously exposed to recombinant human interferon (IFN)-gamma for 20 h, thyroid hormone [L-thyroxine (T4)] in physiological concentrations potentiates the antiviral action of IFN-gamma by more than 100-fold in 4 h. We examined protein kinase activities for their contributions to the mechanism of this posttranslational effect of thyroid hormone. Added concurrently with thyroid hormone, the protein kinase C (PKC) inhibitor CGP-41251 (5 nM) blocked T4 potentiation of IFN-gamma action. Coincubated with CGP-41251, phorbol 12-myristate 13-acetate (PMA) reversed the effect of the inhibitor on thyroid hormone action. U-73122 (10 nM), a phospholipase C inhibitor, also blocked hormone potentiation. KT-5720 (500 nM), a protein kinase A (PKA) inhibitor, completely inhibited the T4 effect, whereas 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) restored hormone action in the presence of KT-5720. In the absence of T4, 8-BrcAMP and PMA, added together to cells in the 4-h paradigm, fully reproduced hormone potentiation of the antiviral effect of IFN-gamma. Incubated individually with IFN-gamma-treated cells, the two agonists had no potentiating action. Thyroid hormone apparently must activate both PKA and PKC in the nongenomic pathway of IFN-gamma action to enhance antiviral activity in HeLa cells.

Nongenomic actions of thyroid hormone

Nongenomic actions of thyroid hormone are by definition independent of nuclear receptors for the hormone and have been described at the plasma membrane, various cell organelles, the cytoskeleton, and in cytoplasm. The actions include alterations in solute transport (Ca2+, Na+, glucose), changes in activities of several kinases, including protein kinase C, cAMP-dependent protein kinase and pyruvate kinase M2 (PKM2), effects on efficiency of specific mRNA translation and mRNA t1/2, modulation of mitochondrial respiration, and regulation of actin polymerization (promotion of formation of F-actin). Iodothyronines also can regulate nongenomically the state of contractile elements in vascular smooth muscle cells (VSMC). The physiologic significance at the cellular level of certain of these actions has been demonstrated, for example, in the cases of myocardiocyte Na+ current, red cell Ca2+ content, and the control by hormone-induced alterations in actin solubility of cell surface activity of iodothyronine 5'-monodeiodinase activity and the intracellular distribution of protein disulfide isomerase activity. The physiologic significance of these actions at the organ or system level is less clear, but extranuclear effects of thyroid hormone on myocardial Na+ channel, sarcoplasmic reticulum Ca(2+)-ATPase activity, and contractile state of VSMC may each contribute to acute effects of thyroid hormone on cardiac output that have recently been described clinically. The molecular mechanisms for nongenomic actions are incompletely understood; relevant binding sites and signal transduction pathways have been described for hormone actions on plasma membrane Ca(2+)-ATPase activity, and PKM2 monomer is known to bind T3 and, as a result, prevent activation of the kinase via tetramer formation. Nongenomic actions of thyroid hormone may have different structure-activity relationships of iodothyronines from those effects that depend upon nuclear receptors; they may have different time courses and may invoke complex signal transduction pathways before the action is detected.

Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane

BACKGROUND

Sevoflurane is an inhalational anesthetic with characteristics suited for use in children. To determine whether the induction, recovery, and safety characteristics of sevoflurane differ from those of halothane, the following open-labeled, multicenter, randomized, controlled, phase III study in children undergoing ambulatory surgery was designed.

METHODS

Three hundred seventy-five children, ASA physical status 1 or 2, were randomly assigned in a 2:1 ratio to receive either sevoflurance or halothane, both in 60% N2O and 40% O2. Anesthesia was induced using a mask with an Ayre's t piece or Bain circuit in four of the centers and a mask with a circle circuit in the fifth center. Maximum inspired concentrations during induction of anesthesia were 7% sevoflurane and 4.3% halothane. Anesthesia was maintained by spontaneous ventilation, without tracheal intubation. End-tidal concentrations of both inhalational anesthetics were adjusted to 1.0 MAC for at least 10 min before the end of surgery. Induction and recovery characteristics and all side effects were recorded. The plasma concentration of inorganic fluoride was measured at induction of and 1 h after anesthesia.

RESULTS

During induction of anesthesia, the time to loss of the eyelash reflex with sevoflurane was 0.3 min faster than with halothane (P < 0.001). The incidence of airway reflex responses was similar, albeit infrequent with both anesthetics. The total MAC.h exposure to sevoflurane was 11% less than the exposure to halothane (P < 0.013), although the end-tidal MAC multiple during the final 10 min of anesthesia was similar for both groups. Early recovery as evidenced by the time to response to commands after sevoflurane was 33% more rapid than it was after halothane (P < 0.001), although the time to discharge from hospital was similar for both anesthetics. The mean ( +/- SD) plasma concentration of inorganic fluoride 1 h after discontinuation of sevoflurane was 10.3 +/- 3.5 microM. The overall incidence of adverse events attributable to sevoflurane was similar to that of halothane, although the incidence of agitation attributable to sevoflurane was almost threefold greater than that attributable to halothane (P < 0.004).

CONCLUSIONS

Sevoflurane compared favorably with halothane. Early recovery after sevoflurane was predictably more rapid than after halothane, although this was not reflected in a more rapid discharge from the hospital. The incidence of adverse events was similar for both anesthetics. Clinically, the induction, recovery, and safety characteristics of sevoflurane and halothane are similar. Sevoflurane is a suitable alternative to halothane for use in children undergoing minor ambulatory surgery.

Thyroid hormone analogues potentiate the antiviral action of interferon-gamma by two mechanisms

L-thyroxine (L-T4) potentiates the antiviral activity of human interferon-gamma (IFN-gamma) in HeLa cells. We have added thyroid hormone and analogues to cells either 1) for 24 h pretreatment prior to 24 h of IFN-gamma (1.0 IU/ml), 2) for 24 h cotreatment with IFN-gamma, 3) for 4, after 20 h cell incubation with IFN-gamma, alone, or 4) for 24 h pretreatment and 24 h cotreatment with IFN-gamma. The antiviral effect of IFN-gamma was then assayed. L-T4 potentiated the antiviral action of IFN-gamma by a reduction in virus yield of more than two logs, the equivalent of a more than 100-fold potentiation of the IFN's antiviral effect. 3,3 of the IFN's antiviral effect. 3,3',5-L-triiodothyronine (L-T3) was as effective as L-T4 when coincubated for 24 h with IFN-gamma but was less effective than L-T4 when coincubated for only 4 h. D-T4, D-T3, 3,3',5-triiodothyroacetic acid (triac), tetraiodothyroacetic acid (tetrac), and 3,5-diiodothyronine (T2) were inactive. When preincubated with L-T4 for 24 h prior to IFN-gamma treatment, tetrac blocked L-T4 potentiation, but, when coincubated with L-T4 for 4 h after 20 h IFN-gamma, tetrac did not inhibit the L-T4 effect. 3,3',5-L-triiodothyronine (rT3) also potentiated the antiviral action of IFN-gamma, but only in the preincubation model. Furthermore, the effects of rT3 preincubation and L-T3 coincubation were additive, resulting in 100-fold potentiation of the IFN-gamma effect. When L-T4, L-T3, or rT3, plus cycloheximide (5 micrograms/ml), was added to cells for 24 h and then removed prior to 24 h IFN-gamma exposure, the potentiating effect of the three iodothyronines was completely inhibited. In contrast, IFN-gamma potentiation by 4 h of L-T4 or L-T3 coincubation was not inhibited by cycloheximide (25 micrograms/ml). These studies demonstrate two mechanisms by which thyroid hormones can potentiate IFN-gamma's effect: 1) a protein synthesis-dependent mechanism evidenced by enhancement of IFN-gamma's antiviral action by L-T4, L-T3, or rT3 preincubation, and inhibition of enhancement by tetrac and cycloheximide, and 2) a protein synthesis-independent (posttranslational) mechanism, not inhibited by tetrac or cycloheximide, demonstrated by 4 h coincubation of L-T4 or L-T3, but not rT3, with IFN-gamma. The protein synthesis-dependent pathway is responsive to rT3, a thyroid hormone analogue generally thought to have little effect on protein synthesis. A posttranslational mechanism by which the antiviral action of IFN-gamma can be regulated has not previously been described.

Increased plasma IGF-1 levels but lack of changes in adipocyte glucose transport in weanling rats with dorsomedial hypothalamic nucleus lesions 1 year after lesion production

Experimental destruction of the dorsomedial hypothalamic nuclei (DMN) in weanling rats exerts an antiaging effect by preventing microalbuminuria and kidney lesions both 1 month and 1 year after lesion production. In the present study we report further on antiaging effects of DMN lesions (DMNL) by measuring glucose transport into adipocytes and plasma levels of insulin-like growth factors 1 and 2 (IGF-I, IGF-II). Male and female weanling Sprague-Dawley rats received bilateral electrolytic lesions in the DMN; sham-operated animals served as controls (SCON). The rats were maintained for 1 year and food intake was measured 3 weeks after surgery and 3 weeks prior to sacrifice. As expected, DMNL resulted in profound reductions of body weight and food intake, with male DMNL rats showing higher body weights and body weight gains than their female counterparts. The same was true of the respective SCON. In male DMNL rats, carcass fat in absolute terms was significantly reduced vs. SCON, but it was comparable among all groups when expressed in percent. Lean body mass (LBM), although significantly reduced in absolute terms in DMNL rats vs. SCON, was, however, significantly higher in male DMNL vs. SCON when expressed in percent, but not in females. LBM laid down per food energy taken in was higher in DMNL rats of both sexes than in their respective SCON. Efficiency of food utilization was normal in male DMNL vs. male SCON but was higher in female DMNL vs. SCON. Both male and female DMNL rats had significantly higher plasma IGF-1 concentrations than their respective SCON, and male DMNL rats had higher values than female DMNL rats. Plasma concentrations of IGF-II were significantly higher in DMNL vs. SCON, but only in females. Under both basal and insulin-stimulated conditions, DMNL rats had normal 3-0-methylglucose flux in adipocytes from epididymal fat pads vs. SCON. However, DMNL and SCON responded similarly to the stimulating effect of insulin. Although one-year-old rats may not be considered "aged", we do consider the observed lack of a drop in plasma IGF-I levels that occurs with aging as an "anti-aging" effect of DMN lesions.

Sequence of the nucleocapsid protein gene of subgroup A and B avian pneumoviruses

The nucleocapsid protein (N) gene of two subgroup A and one subgroup B strains of avian pneumovirus has been cloned and sequenced. The gene of all three isolates comprised 1197 nucleotides (nt), which formed a single major open reading frame, potentially encoding a protein of 391 amino acid residues. The N gene of the two subgroup A isolates differed by only 1 nt but differed by 282 (24%) nt and 35 (11%) amino acids from the B isolate. The predicted protein was identical in length to that of human, bovine and ovine respiratory syncytial viruses, the amino acid identity being approximately 41% overall but with some regions of identity > 90%.

Neural control of vocalization: respiratory and emotional influences

Previous research has shown that a region of the midbrain, the periaqueductal gray matter (PAG), is critical for vocalization. In this review, we describe the results of previous investigations in which we sought to find out how PAG neurons integrate the activity and precise timing of respiratory, laryngeal, and oral muscle activity for natural-sounding vocalization using the technique of excitatory amino acid microinjections in cats. In these studies, all surgical procedures were carried out under deep anaesthesia. In the precollicular decerebrate cat two general types of vocalization, classified as voiced and unvoiced, could be evoked by exciting neurons in the lateral part of the intermediate part of the PAG. The patterns of evoked electromyographic activity were strikingly similar to previously reported patterns of human muscle activity. Coordinated patterns of activity were evoked with just-threshold excitation leading to the conclusion that patterned muscle activity corresponding to the major categories of voiced and voiceless sound production are represented in the PAG. In a parallel series of human and animal experiments, we also determined that the speech and vocalization respiratory patterns are integrated and coordinated with afferent signals related to lung volume. These data have led to the proposal of a new hypothesis for the neural control of vocalization: that the PAG is a crucial brain site for mammalian voice production, not only in the production of emotional or involuntary sounds, but also as a generator of specific respiratory and laryngeal motor patterns essential for human speech and song.

Aging and the hypothalamus: research perspectives

There are several hypothalamic theories of aging, none of which has been validated. An approach to validation is to search for consequences of anatomic ablations of hypothalamic regions that are functional hallmarks of aging, or consequences of ablation that postpone the appearance of hallmarks of aging or extend longevity. Ablation of the hypothalamic ventromedial nucleus (VMN) in the weanling rat is associated with subsequent increased body fat, glucose intolerance, hyperlipidemia, and decreased renal function. Each of these consequences is characteristic of aging in humans and in several animal models of aging. Ablation of the hypothalamic dorsomedial nucleus (DMN) in the weanling rat leads to a symmetrically smaller animal with normal glucose and lipid metabolism, decreased body fat for size, and reduced risk of decreased renal function and circulating IGF-I levels. These are findings consistent with calorie restriction models in rodents that significantly extend life span. This review compares outcomes of lesions in the VMN, DMN, and lateral hypothalamic area (LHA) for relevance to aging. To establish a relationship between these anatomic areas of the hypothalamus and aging, it is concluded that the VMN, DMN, and LHA lesions should be examined for impact on longevity and compared with data obtained from simultaneously studied intact ad-lib-fed and 40% calorie-restricted animals. Lesioned animals also should be rigorously studied for neurotransmitters (e.g., neuropeptide Y, beta-endorphin, serotonin, corticotropin-releasing factor, and galanin), and for behavioral changes consistent with aging, for accumulation of specific tissue lipofuscin and amyloid that are associated with normal aging and for other age-dependent findings, such as incidence of tumors and cataract.

Potentiation by thyroxine of interferon-gamma-induced HLA-DR expression is protein kinase A- and C-dependent

L-Thyroxine (T4) and 3,3',5-L-triiodothyronine (T3) potentiate the antiviral state induced by interferon-gamma(IFN-gamma) in homologous cells by a mechanism that is dependent upon calcium/phospholipid-dependent protein kinase (PKC). L-T4 and T3 also potentiate induction by IFN-gamma of MHC class II HLA-DR antigen expression in HeLa cells. In the present studies of HLA-DR expression, the PKC inhibitor staurosporine (0.1-1 nM) enhanced the expression of HLA-DR when the inhibitor was added simultaneously with IFN-gamma, 100 IU/ml. In the presence of IFN-gamma and 10(-7) M T4, the same concentrations of staurosporine inhibited potentiation of HLA-DR expression by thyroid hormone. A more specific PKC inhibitor, CGP41251 (0.5-5 nM), similarly enhanced HLA-DR expression in the presence of IFN-gamma but inhibited thyroid hormone potentiation of antigen expression. Both actions of CGP41251 were suppressed when cells were also treated with phorbol 12-myristate 13-acetate (PMA). A phospholipase C inhibitor, U73122 (1-1000 nM), did not alter the potentiating ability of T4, although it inhibited in a concentration-dependent manner the expression of HLA-DR induced by IFN-gamma. The potentiating effect of T4 was much more sensitive to a cyclic AMP-dependent protein kinase (PKA) inhibitor,KT5720 (1-1000nM), than was the induction of HLA-DR by IFN-gamma. The inhibitory effects of KT5720 were reversed by concurrent 8-bromo-cAMP treatment. The calmodulin antagonist W-7 (5-50 microM) did not alter IFN-gamma induction of HLA-DR in either the presence or absence of T4. HLA-DR expression in HeLa cells appears to be under PKC-associated inhibition; IFN-gamma reverses this inhibition to promote the appearance of the DR antigen. In contrast, potentiation by T4 of induction of HLA-DR by IFN-gamma requires activation of PKC. PKA is involved both in DR induction by IFN-gamma and in potentiation of the latter by T4. Thus, PKA and PKC have discrete roles in IFN-gamma-induced MHC class II antigen expression and its modulation by thyroid hormone.

The effects of cold, touch, and chemical stimulation of the anterior faucial pillar on human swallowing

Cold stimulation of the oropharyngeal mucosa, including the faucial pillar region, is used a specific technique for the treatment of swallowing disorders. The physiological mechanisms underpinning this clinical technique are unclear. Thermal (cold), chemical (saline, glucose and water), mechanical (light touch) and feigned stimulation of the faucial pillar were assessed for their effects on the latency to swallow and the repetitive frequency of swallowing. There was no significant difference between these variables following light stimulation of the faucial pillar with a metal probe warmed to body temperature compared with feigned stimulation. However, cold touch stimulation evoked a significant increase in swallowing latency and repetitive frequency compared to feigned stimulation. The results suggest the existence of thermo-sensitive receptors in the faucial pillars that evoke swallowing when stimulated by cold touch. The clinical and physiological importance of these findings are discussed.

Brain stem integration of vocalization: role of the nucleus retroambigualis

1. The descending pathways that mediate the periaqueductal gray (PAG)-evoked coordination of respiratory, laryngeal, and orofacial activity for vocalization have yet to be delineated. Two hypotheses have been offered. One theory is that this activity is mediated by a diffuse descending projection to parvocellular reticular interneurons, adjacent to the relevant laryngeal and orofacial motoneuronal pools. The second hypothesis is that the motor activity for vocalization is integrated via a projection from the PAG to a caudal medullary column of neurons, the nucleus retroambigualis (NRA). These hypotheses were tested with the use of a series of medullary transections combined with PAG stimulation. Transections that eliminated, in a series of caudal-to-rostral steps, the NRA, also eliminated the PAG-evoked cricothyroid and most of the thyroarytenoid laryngeal motor activity. These results indicate that the final common pathway for much of the laryngeal activity in PAG-evoked vocalization includes un initial synapse in the caudal medulla, presumably in the NRA. 2. The electromyographic changes evoked by microinjection of D,L-homocysteic acid (DLH) in the NRA of the unanesthetized, precollicular decerebrate cat were analyzed in order to delineate the NRA contribution to the coordinated respiratory, laryngeal, and oral muscle changes in vocalization. A total of 415 DLH injection sites were located at or caudal to the level of the obex. Vocalization was evoked at 46 of these sites, which were all confined to a restricted region of the ventrolateral medulla 1-3 mm caudal to the obex. This region corresponded to the rostral half of the NRA and the immediately adjacent medullary tegmentum. 3. In all experiments evidence was obtained that variable muscle activation, rather than functional and integrated muscle patterns, was represented within the NRA. Vocalization evoked by DLH microinjection in the NRA was usually associated with excitation of the cricothyroid, thyroarytenoid, external oblique, internal oblique, internal intercostal, and diaphragm muscles that occurred in a different manner from site to site. That is, injection at sites separated by 0.3-0.5 mm evoked quite different responses. 4. NRA-evoked vocalization was compared with PAG-evoked vocalization using small injections (1.5-4.5 nl) into each region. As well, larger microinjections (15-120 nl) into NRA were made for comparison with previous results from the PAG using similar doses. Within the PAG, stereotyped and relatively "fixed" patterns of muscle activity are represented, whereas within the NRA there was no representation of specific muscle patterns, but rather a partial topographic separation of "premotor neurons" regulating different muscles. Correspondingly, stereotyped vocalizations were never evoked from the NRA. Further, most NRA-evoked vocalizations were unusual in quality and would not be identified generally as feline. 5. Evidence was obtained for a separation of pathways from the PAG regulating sound production and orofacial modulation of that sound. In contrast to the results from the PAG, excitation of NRA neurons rarely evoked activity in the oral muscles (genioglossus or anterior belly of digastric) or orofacial modulation of sound production. 6. Our finding suggests that the NRA serves as an important substrate for the generation of respiratory pressure and larynges adduction, which are two essential aspects of not only vocalization but also several behaviors involving Valsava maneuvers such as coughing, vomiting, and defecation.

Effect of antiemetic therapy on recovery and hospital discharge time. A double-blind assessment of ondansetron, droperidol, and placebo in pediatric patients undergoing ambulatory surgery

BACKGROUND

Postoperative nausea and vomiting continue to be a significant problem for pediatric ambulatory surgery patients. Although ondansetron has been demonstrated to be effective in the prophylactic treatment of postoperative nausea and vomiting (surrogate end point) no one has demonstrated a benefit of antiemetic therapy on patient recovery, postanesthesia care unit length of stay, and hospital length of stay (nonsurrogate end points). In a double-blind manner, the effects of ondansetron, droperidol, and placebo on the incidence of emesis, postanesthesia care unit stay, and hospital discharge time were evaluated in children undergoing dental surgery.

METHODS

The subjects were 102 children aged 2-8 years undergoing complete dental restoration. All patients received midazolam before undergoing inhalation induction of anesthesia with N2O/O2 and halothane. Anesthesia was maintained with N2O/O2 and alfentanil. Patients were then randomized to receive ondansetron (0.1 mg/kg), droperidol (75 micrograms/kg), or placebo (normal saline) in a double-blind fashion. At the conclusion of the anesthesia, a trained nurse observer assessed patient recovery and recorded the time patients met specified criteria for postanesthesia care unit and hospital discharge as well as episodes of emesis in the hospital and at home during the first 24 hr after surgery.

RESULTS

Ninety-five patients completed the study. The three antiemetic groups were similar with respect to age, weight, length of surgery, dose of alfentanil, and route of preanesthetic medication. The 24-hr incidence of emesis was significantly less with ondansetron (9%) than with placebo (35%) or droperidol (32%). Ondansetron-treated patients had significantly shorter hospital stays than droperidol-treated patients, but recovery parameters were similar between the ondansetron- and placebo-treated patients.

CONCLUSIONS

Ondansetron is an effective prophylactic antiemetic agent for children undergoing dental surgery. Compared with droperidol, ondansetron decreases the length of hospital stay, but compared to placebo, there were no differences in the patient recovery parameters.

Abnormal cell proliferation and p52/p35-CSK expression in the colons of aging rats

In rodents and in humans, aging is associated with increased gastrointestinal epithelial cell proliferation and an expanded crypt proliferative compartment similar to that seen in the preneoplastic bowel. We have compared the distribution of a series of cytoskeletal antigens that are modified when colonic cancer cells differentiate in vitro in the colon of young (4-7 month) and aging (22-26 month) Fischer 344 rats. Two such proteins, p52 and p35, (that are increased in cultured senescent cells) differ in their position in the crypt axis and subcellular localization between young and aging rats. In young rats, immunoreactive p52 protein is present solely near the colonic crypt surface epithelium but in aging rats p52 expressing cells are found deeper in crypts. The intracellular localization of p35 also differs markedly in young and aging animals. The distribution of these proteins appears to be a reproducible biomarker of aging. Antigenic changes similar to those observed in aging colons also are seen in crypt cells of patients with ulcerative colitis and in the flat colonic mucosa of patients with adenomatous polyps and colon cancer. The combination of proliferative and differentiation changes suggest that the flat mucosa of the colon of aging rats has preneoplastic features.

Inositol phosphates modulate human red blood cell Ca(2+)-adenosine triphosphatase activity in vitro by a guanine nucleotide regulatory protein

D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] inhibits human red blood cell (RBC) Ca(2+)-stimulable, Mg(2+)-dependent adenosine triphosphatase (Ca(2+)-ATPase) activity in vitro. Because we have previously shown that adrenergic receptors exist on the human mature RBC membrane and can modulate Ca(2+)-ATPase activity, we examined the possibility that a guanine nucleotide regulatory protein (G protein) mediated the Ins(1,4,5)P3 effect. Guanosine 5'-O-(3-thiotrisphosphate) (GTP gamma S) 10(-4) mol/L also inhibited RBC Ca(2+)-ATPase activity. Pertussis toxin 200 ng/mL blocked the effects of both Ins(1,4,5)P3 and GTP gamma S on Ca(2+)-ATPase activity. In separate studies, pertussis toxin-catalyzed adenosine diphosphate (ADP) ribosylation was shown to occur in RBC membranes under conditions in which measurements of Ca(2+)-ATPase activity were performed. When Ins(1,4,5)P3 10(-7) mol/L and GTP gamma S 10(-6) mol/L were added to membranes concurrently, their inhibitory actions on the enzyme were additive. At greater concentrations of Ins(1,4,5)P3 (10(-6) to 10(-5) mol/L) and GTP gamma S (10(-4) mol/L), the inositol phosphate reversed the inhibitory effect of GTP gamma S. These observations indicate that the novel effect of Ins(1,4,5)P3 on the activity of a plasma membrane Ca(2+)-ATPase depends at least in part on the action of a pertussis toxin-susceptible G protein.

Structure-activity relationships of milrinone analogues determined in vitro in a rabbit heart membrane Ca(2+)-ATPase model

The cardiac activity of a series of analogues of the positive inotropic bipyridines amrinone (5-amino-[3,4'-bipyridin]-6(1H)-one) and milrinone (2-methyl-5-cyano-[3,4'-bipyridin]-6(1H)-one) was evaluated in vitro in a rabbit myocardial membrane Mg(2+)-dependent, Ca(2+)-stimulable adenosine triphosphatase (Ca(2+)-ATPase) model and structure-activity relationships were compared for nine closely related derivatives. In the present studies, a 5-bromo analogue of milrinone stimulated myocardial membrane Ca(2+)-ATPase significantly (10(-7) M; P < 0.001 vs control, with 67% of the activity of milrinone), whereas a 2'-methyl-2H-milrinone derivative was inactive. Although amrinone was inactive in this assay, its 2-methyl analogue was stimulatory. However, analogues lacking a 2-substituent (with or without a 5-cyano group) or with the 3-N position blocked by a methyl group did not stimulate myocardial membrane Ca(2+)-ATPase activity. Structural data for these bipyridines show that those with either a 2- or 2'-methyl substituent have a twist conformation, whereas those without are nearly planar. Activity data reveal that those bipyridines with a nonplanar conformation are more active in the Ca(2+)-ATPase assay. Further study of milrinone analogues with a 2'-methyl substituent shows that even though the effect on the twist angle is equivalent to that of 2-methyl substitution, these analogues are less potent. Data for this series reveal that the prerequisites for Ca(2+)-ATPase stimulation include not only a 2-methyl to maintain a twist conformation but also a free 3-N position and a 5-substituent. This model for optimal activity in the myocardial membrane Ca(2+)-ATPase system differs from those proposed for phosphodiesterase enzyme receptor recognition only in the requirement for a nonplanar molecule. We have previously shown that milrinone, but not amrinone, shares structural homology with thyroxine and was able to stimulate myocardial membrane Ca(2+)-ATPase activity in a manner similar to the thyroid hormone. Additionally, milrinone, but not amrinone, was an effective competitor for thyroxine binding to the serum transport protein transthyretin. Analysis of the milrinone-transthyretin crystal complex confirms the structural homology between milrinone and thyroid hormone which is not shared by amrinone. Modeling studies of the binding interactions of milrinone analogues indicate that the 2-desmethylmilrinone analogue, the most inhibitory analogue, lacks the hydrophobic contacts present in milrinone in its transthyretin-bound complex.(ABSTRACT TRUNCATED AT 400 WORDS)

Sequence and in vitro expression of the phosphoprotein gene of avian pneumovirus

The phosphoprotein (P) gene of two subgroup A strains of avian pneumovirus comprised 855 nucleotides containing only one substantial open reading frame encoding a protein of 278 amino acids, with a predicted M(r) of 30,323. In vitro translation of P mRNA in a wheat germ system resulted in the synthesis of two polypeptides of M(r) 35,000. Comparison of the deduced P protein sequence with that of the known mammalian pneumoviruses revealed overall amino acid identities ranging from 31 to 34.5%, suggesting a distant relationship. However, there was a much higher identity (63.2-68.4%) in a region of 57 residues, which included a heptad repeat sequence.

Breathing patterns during spontaneous speech

Lung volumes, speech intensity, the linguistic location of inspirations, and the variability of each, were studied during spontaneous speech in 6 healthy young women over 7 to 10 sessions each, using respiratory inductance plethysmography. Although average lung volume levels were within the vital capacity range previously reported for speech (Hixon, Goldman, & Mead, 1973), significant inter- and intrasubject variability was observed. This variability was considerable for some subjects (average initiation lung volume varying between 42 and 63% VC over the sessions) and relatively small for others (between 47 and 53% VC). Some of the lung volume variation was associated with changes in mood state, examined by self-report questionnaire at each measurement occasion. Linguistic factors were important influences in the lung volume variation. The majority of breaths in the conversations and monologues preceded structural (clause) boundaries. The volume of air inspired preutterance was found to be linked to the length of the ensuing breath group in each of our 6 subjects, as longer breath groups, spanning up to seven clauses in the spontaneous speech, were anticipated by inspiring to a higher lung volume. The subjects used a comfortable speaking intensity range, which varied for different individuals and sessions over 4 to 18 dB. Increases in speech intensity within individual ranges were not associated with increased lung volumes. The data provide novel insight into associations between physiological and linguistic factors in the control of speech breathing, and are suggestive of the existence of neural planning of the respiratory system, in anticipation of the demands of the utterance.

Treatment of mild hypertension with low once-daily doses of a sustained-release capsule formulation of verapamil

The efficacy and safety of a low dose (120 mg) of a sustained-release capsule formulation of verapamil administered once daily in the treatment of 42 patients with mild hypertension were assessed in this clinical trial. After a 4-week placebo washout period (baseline), patients with diastolic clinic blood pressures of 91 to 100 mm Hg inclusive were treated for 4 weeks with once-daily verapamil sustained-release 120 mg capsules. Clinic blood pressure was measured and 24-hour ambulatory blood pressure monitoring was performed at the end of both the baseline and the 4-week treatment periods. Twenty-four hour, day, and night systolic and diastolic ambulatory blood pressure were significantly (P < 0.01) reduced in the entire study population (24-hour, -5/-4 mm Hg; day, -6/-4 mm Hg; night, -4/-3 mm Hg). On the basis of mean daytime (6 AM to 6 PM) ambulatory diastolic blood pressure, patients were stratified into subgroups of patients with confirmed (> 85 mm Hg) and unconfirmed mild hypertension (< or = 85 mm Hg). The magnitude of the mean change in systolic and diastolic blood pressure was greater in the group of patients with confirmed mild hypertension than the group with unconfirmed hypertension. The incidence of adverse experiences was low in frequency and events were of mild severity; quality of life scores improved (P = 0.02). Low daily doses (120 mg) of verapamil sustained-release capsules provide a well-tolerated and sustained antihypertensive effect over 24 hours in patients with mild hypertension.

Coronary vasoconstriction mediated by endothelin-1 in neonates. Reversal by nitroglycerin

To determine the role of the vasoconstrictor peptide endothelin-1 in cardiopulmonary bypass in neonates, we measured plasma endothelin-1 concentrations in infants before and after cardiopulmonary bypass for arterial switch procedures and studied the effects of endothelin-1 on coronary tone and contractility in normal and reperfused neonatal pig hearts. Endothelin-1 blood concentrations (picograms per milliliter, mean +/- standard error) were significantly higher in neonates with arterial transposition and in umbilical venous blood (22.9 +/- 2.3 and 19.2 +/- 2.9, respectively) than in older children with atrial septal defects (13.2 +/- 1.6) or in healthy adults (10.7 +/- 2.5). After cardiopulmonary bypass, endothelin-1 concentrations increased 29% in neonates undergoing arterial switch procedure and 28% in children undergoing atrial septal defect repair (p < 0.05 versus before bypass). In isolated, blood-perfused neonatal pig hearts, endothelin-1 had dose-related coronary constrictor and inotropic effects between 25 and 100 pmol. Endothelin-1 concentrations that did not increase coronary perfusion pressure (5 to 10 pmol) caused significant coronary constriction in the presence of norepinephrine (10 nmol/L). During reperfusion after 30 minutes of global normothermic ischemia, the coronary vasoconstrictor effects of both endothelin-1 alone and endothelin-1 plus norepinephrine were significantly enhanced. Nitroglycerin reversed vasoconstriction produced by endothelin-1 and endothelin-1 plus norepinephrine both before and after ischemia-reperfusion. We conclude that endothelin-1 concentrations are significantly elevated in neonates and are further increased after cardiopulmonary bypass. Coronary vasoconstriction caused by endothelin-1 is enhanced by ischemia-reperfusion and by norepinephrine present in concentrations typically observed after neonatal cardiopulmonary bypass. Nitroglycerin reverses coronary vasoconstriction induced by endothelin-1 and may therefore be beneficial in the postoperative management of neonates after cardiac operations.

Preanesthetic medication with intranasal midazolam for brief pediatric surgical procedures. Effect on recovery and hospital discharge times

BACKGROUND

The perfect preanesthesia medication and its ideal route of administration are still debated, but for pediatric surgical patients undergoing brief procedures, preanesthesia medication is frequently omitted because of the concern that it will prolong the child's recovery from anesthesia. The effects of nasally administered midazolam on anesthetic recovery and hospital discharge times were determined in 88 ASA physical status 1 and 2 ambulatory surgical patients undergoing a brief surgical procedure.

METHODS

Using a randomized, double-blind, placebo-controlled design, 88 ambulatory surgical patients 10-36 months of age undergoing myringotomy and tube insertion were entered into the study. All patients were randomly assigned to one of three medication groups. One group received 0.2 mg/kg intranasal midazolam; a second group received 0.3 mg/kg intranasal midazolam; and the third group received intranasal saline drops. All patients were anesthetized with nitrous oxide, oxygen, and halothane administered via mask. The duration of anesthesia lasted between 9 and 10 min. After preanesthetic medication, the children were evaluated for ease of separation and induction of anesthesia. In addition, the time from when the anesthetic was discontinued until the child recovered from anesthesia and the time the child was discharged home were recorded by a nurse observer blinded to the patient grouping.

RESULTS

Children receiving midazolam had smoother, calmer parent-child separation and anesthesia induction scores, and their anesthesia recovery times and hospital discharge times were the same as those receiving placebo.

CONCLUSIONS

For children undergoing brief surgical procedures, nasal midazolam provides satisfactory anxiolysis without delaying anesthesia recovery and hospital discharge.

Clinical characteristics of sevoflurane in children. A comparison with halothane

BACKGROUND

For pediatric patients, sevoflurane may be an alternative to halothane, the anesthetic agent used most commonly for inhalational induction. The induction, maintenance, and emergence characteristics were studied in 120 unpremedicated children 1-12 yr of age randomly assigned to receive one of three anesthesia regimens: sevoflurane with oxygen (group S), sevoflurane with nitrous oxide and oxygen (group SN), or halothane with nitrous oxide and oxygen (group HN).

METHODS

Anesthetic was administered (via a Mapleson D, F or Bain circuit) beginning with face mask application in incremental doses to deliver maximum inspired concentrations of 4.5% halothane or 7% sevoflurane. End-tidal concentrations of anesthetic agents and vocal cord position were noted at the time of intubation. Elapsed time intervals from face mask application to loss of the eyelash reflex, intubation, surgical incision, and discontinuation of the anesthetic were measured. Heart rate, systolic, diastolic, and mean blood pressures, and end-tidal anesthetic concentrations were measured at fixed intervals. Anesthetic MAC-hour durations were calculated. The end-tidal concentration of anesthetic was adjusted to 1 MAC (0.9% halothane, 2.5% sevoflurane) for at least the last 10 min of surgery. Intervals from discontinuation of anesthetic to hip flexion or bucking, extubation, administration of first postoperative analgesic, and attaining discharge criteria from recovery room were measured. Venous blood was sampled at anesthetic induction, at the end of anesthesia, and 1, 4, 6, 12, and 18-24 h after discontinuation of the anesthetic for determination of plasma inorganic fluoride content.

RESULTS

Induction of anesthesia was satisfactory in groups SN and HN. Induction in group S was associated with a significantly greater incidence of excitement (35%) than in the other groups (5%), resulting in a longer time to intubation. The end-tidal minimum alveolar concentration multiple of potent inhalational anesthetic at the time of intubation was significantly greater in patients receiving halothane than in patients receiving sevoflurane. Induction time, vocal cord position at intubation, time to incision, duration of anesthesia, and MAC-hour duration were similar in the three groups. During emergence, the time to hip flexion was similar among the three groups, whereas the time to extubation, time to first analgesic, and time to attaining discharge criteria were significantly greater in group HN than in groups S and SN. Mean heart rate and systolic blood pressure decreased during induction in group HN but not in groups S and SN. The maximum serum fluoride concentration among all patients was 28 microM.

CONCLUSIONS

Sevoflurane with nitrous oxide provides satisfactory anesthetic induction and intubating conditions; however, induction using sevoflurane without nitrous oxide is associated with a high incidence of patient excitement and prolonged time to intubation. There were greater decreases in heart rate and systolic blood pressure during induction with halothane than with sevoflurane; however, these differences may be dose-related. The more rapid emergence with sevoflurane when compared with halothane is consistent with the low solubility of sevoflurane in blood and tissues. Children receiving sevoflurane for up to 9.6 MAC-hours did not develop high serum fluoride concentrations.

Self-efficacy and confidence in outcomes as determinants of self-care practices in inner-city, African-American women with non-insulin-dependent diabetes

The purpose of this study was to examine the extent to which perceived self-efficacy and confidence in outcomes, selected demographic variables, and disease characteristics (age, duration of diabetes, presence of documented complications) affect an individual's adherence over time to a diabetes regimen of home glucose testing, medication/insulin administration, diet, and exercise. A convenience sample of 118 inner-city, African-American women with type II, non-insulin-dependent diabetes mellitus receiving outpatient care at a large urban hospital were asked to complete measures of each of the psychosocial variables on two occasions, separated by an interval of 4 to 5 months, and coinciding with their next scheduled clinic visit. Bivariate and multivariate analyses at Times 1 and 2 demonstrated the ability of self-efficacy alone to explain diet, exercise, and home-testing behaviors while suggesting variability within individuals in sense of self-efficacy over time.

Maximum acceptable frequencies for females performing a drilling task in different wrist postures

This paper presents a study on the effect of wrist posture; flexion, extension, ulnar deviation, and radial deviation on maximum acceptable frequencies (MAF) for a drilling task using a psychophysical approach. Twelve females were selected from a college population to serve as subjects and an adjustable workstation was used to simulate a drilling task. The results revealed that flexion, extension, and radial deviation all had a significant effect on MAF but, ulnar deviation did not. The postures have been ranked in order of possible risk of contributing to CTD injury, with neutral having the lowest rank (lowest risk) and flexion having the highest rank (greatest risk).

Endothelium-dependent regulation of coronary tone in the neonatal pig

We examined the effects of endothelium-dependent responses on coronary perfusion pressure (CPP) in isolated, blood-perfused neonatal pig hearts under conditions of controlled coronary flow. Baseline CPP was increased 8%-21% by the cyclooxygenase inhibitor indomethacin (10-100 microM), and 30%-92% by NG-monomethyl-L-arginine (L-NMMA, 10-100 microM), an inhibitor of nitric oxide (NO) synthase, suggesting that both prostaglandin and nitric oxide synthesis contribute to basal coronary tone. Both acetylcholine (ACh) and bradykinin (BK) decreased CPP. These effects were enhanced by preconstriction with endothelin-1. L-NMMA markedly attenuated BK-induced coronary vasodilation and converted the ACh response to constriction, indicating a significant role for NO release in these responses. After 1 h of total, global normothermic ischemia and 45 min of reperfusion, vasoconstrictor responses to endothelin-1 and ACh were enhanced, while BK-induced dilation was significantly reduced. L-Arginine supplementation during reperfusion did not restore vasodilatory responses to ACh or BK. The magnitude of L-NMMA-induced coronary vasoconstriction during reperfusion was similar to that observed without ischemia-reperfusion. Coronary vasodilation in response to sodium nitroprusside, a NO precursor that causes endothelium-independent vasodilation by directly activating smooth muscle guanylate cyclase, was unaffected by ischemia-reperfusion. We conclude that NO production in the neonatal coronary circulation contributes to both basal tone and the response to ACh and BK. After ischemia-reperfusion, basal NO production and smooth muscle relaxation mediated by guanylate cyclase are intact, whereas agonist-stimulated dilation is significantly impaired.

Pharmacokinetics of methylprednisolone in elderly and young healthy males

OBJECTIVE

To characterize and compare the pharmacokinetics of a single intravenous dose of methylprednisolone in elderly and young healthy males.

DESIGN

A randomized, parallel pharmacokinetic trial.

SETTING

A public university-affiliated hospital.

SUBJECTS

Seven healthy, elderly white males (aged 69 to 82 years) and five healthy, young white males (aged 24 to 37 years) who gave informed consent and fulfilled all screening criteria.

MEASUREMENTS

Serial blood samples were obtained over a 24-hour study period after intravenous administration of a 10-mg dose of methylprednisolone. Serum methylprednisolone concentrations were determined by high performance liquid chromatography and utilized to determine the pharmacokinetic parameters.

RESULTS

Methylprednisolone serum concentrations declined in a linear manner in both groups. However, 4 hours after the dose, the mean serum concentration of methylprednisolone was 50.9 +/- 15.1 ng/mL in the elderly group and 37.6 +/- 7.5 (P = 0.07) ng/mL in the young group. The clearance of methylprednisolone was 237 +/- 62 mL/h/kg, with a volume of distribution of 1.10 +/- 0.07 L/kg, for the elderly group, whereas the young males had a mean drug clearance of 359 +/- 90 mL/h/kg (P < 0.05) and a mean volume of distribution of 1.28 +/- 0.34 L/kg. The half-life of methylprednisolone ranged from 1.90 to 5.40 hours in the elderly group; the range was 1.99 to 3.31 hour (P = 0.016) in the young group.

CONCLUSION

A slower methylprednisolone clearance was noted in the elderly group compared with the young counterparts. This pharmacokinetic alteration seen in healthy elderly subjects may contribute to the increased incidence of adverse effects from chronic glucocorticoid therapy that has been observed among elderly patients.

Prolonged neonatal myocardial preservation with a highly buffered low-calcium solution

Optimal methods of myocardial preservation remain controversial in the neonate. This study compared prolonged hypothermic storage of neonatal hearts with modified University of Wisconsin solution (group I) with a solution formulated to promote anaerobic glycolysis by providing proton buffering with histidine (100 mmol/L) and exogenous glucose and insulin (group II). Hearts from piglets aged 3 to 5 days were given a single dose of either solution (n = 6 each), subjected to 20 hours of global ischemia at 4 degrees C, and reperfused with an erythrocyte-enhanced perfusate in an isovolumic Langendorff preparation. After 1 hour of reperfusion, in comparison with hearts preserved with University of Wisconsin solution, those in group II demonstrated (mean +/- standard error of the mean) greater left ventricular developed pressure (101 +/- 7 versus 62 +/- 9 mm Hg, p < 0.01) and the first derivative of left ventricular pressure (816 +/- 23 versus 614 +/- 69 mm Hg.sec-1, p < 0.05). Diastolic indices were reduced to a similar degree in the two groups. Myocardial oxygen consumption was significantly greater (38.8 +/- 2.4 versus 11.8 +/- 2.4 microliters oxygen.min.g-1, p < 0.01) in group II hearts. Group I hearts vasoconstricted (6% increase in coronary vascular resistance) in response to an intracoronary infusion of acetylcholine (20 nmol.min-1); in contrast, acetylcholine produced coronary dilation in group II hearts (5% decrease in coronary resistance, p < 0.02) that was similar to that observed in nonischemic control hearts. These results demonstrate enhanced preservation of myocardial contractility, oxidative metabolism, and vascular function in neonatal hearts provided by a solution designed to buffer protons and promote anaerobic glycolysis during ischemia.

Brain stem integration of vocalization: role of the midbrain periaqueductal gray

1. The contribution of the midbrain periaqueductal gray (PAG) to the central regulation of vocalization was investigated by analyzing the electromyographic (EMG) changes in respiratory, laryngeal, and oral muscles evoked by microinjection of D,L-homocysteic acid (DLH) in the PAG of unanesthetized, precollicular decerebrate cats. Moderate to large (6-40 nmol) doses of DLH evoked natural-sounding vocalization as well as increases in inspiratory depth and respiratory rate. 2. Two basic types of vocalization were evoked, each associated with a distinct and characteristic pattern of respiratory, laryngeal and oral EMG changes. Type A vocalization (voiced sounds such as howl/mew/growl) was characterized by excitation of the cricothyroid (CT) and thyro-arytenoid (TA) muscles, and inhibition of the posterior crico-arytenoid (PCA) muscle, whereas type B vocalization (unvoiced hiss sounds) was characterized by excitation of the PCA and TA muscles and no significant activation of the CT muscle. In addition, stronger expiratory (external oblique, internal oblique, internal intercostal) EMG increases were associated with type A responses, and larger increases in genioglossus and digastric muscle activity were associated with type B responses. 3. Microinjections of small doses of DLH (300 pmol-3 nmol), also evoked patterned changes in muscle activity (usually without audible vocalization) that, although of lower amplitude, were identical to those evoked by injections of moderate to large DLH doses. In no such experiments (175 sites) were individual muscles activated by small dose injections of DLH into the PAG. Further, type A vocalization/muscle patterns were evoked from PAG sites caudal to those at which type B vocalization/muscle patterns were evoked. 4. Considered together these results indicate: that the PAG contains topographically separable groups of neurons that coordinate laryngeal, respiratory, and oral muscle patterns characteristic of two fundamental types of vocalization and that the underlying PAG organization takes the form of a representation of muscle patterns, rather than individual muscles. 5. The patterns of EMG activity evoked by excitation of PAG neurons were strikingly similar to previously reported patterns of EMG activity characteristic of major phonatory categories in higher species, including humans (e.g., vowel phonation, voiceless consonant phonation). These findings raise the possibility that the sound production circuitry of the PAG could well be utilized by cortical and subcortical "language structures" to coordinate basic respiratory and laryngeal motor patterns that are necessary for speech.

Thyroid hormone potentiates the antiviral action of interferon-gamma in cultured human cells

Human interferon-gamma (hIFN gamma) exhibits a number of biological effects, including antiviral activity in homologous cells. The antiviral activity of recombinant (r) hIFN gamma, estimated by inhibition of vesicular stomatitis virus yield, was potentiated up to 120-fold in human fibroblast (BG-9) cells exposed to free L-T4 (0.5 x 10(-10) mol/L). Thyroid hormone alone did not induce the antiviral state in BG-9 cells. L-T3 also potentiated the antiviral action of rhIFN gamma, but D-T4 and D-T3 were ineffective. The antiviral effect of hIFN alpha in BG-9 cells was not influenced by thyroid hormone. Exposure of rhIFN gamma-treated BG-9 cells to L-T4 for only 3 h was sufficient to potentiate hIFN gamma-mediated antiviral activity. Similar potentiation by L-T4 of the antiviral effect of rhIFN gamma in HeLa cell cultures was also observed. Although the mechanism of potentiation of rhIFN gamma action by thyroid hormone is incompletely understood, the absence of antiviral activity of thyroid hormone alone indicates that the iodothyronine effect does not depend upon hormonal action on genes able to be stimulated by IFN gamma.

Variability and consistency in speech breathing during reading: lung volumes, speech intensity, and linguistic factors

Lung volumes during reading and associated factors such as speech intensity and linguistic influences were studied in six healthy young women over 7 to 10 sessions, using respiratory inductive plethysmography. Intrasubject variability of lung volumes over the sessions was almost as great as the intersubject variability. Some of the intrasubject variability was associated with natural variations of speech intensity within a "comfortable loudness" range. The lung volume variability during reading is contrasted with high degrees of both inter- and intrasubject consistency in the location of inspirations, which occurred almost exclusively at grammatically appropriate places in the texts (paragraph, sentence, clause, and phrase boundaries). Within each reading passage, lung volumes were significantly increased for (a) louder utterances, (b) inspirations at sentence and paragraph boundaries compared to inspirations at other locations within sentences, (c) longer utterances compared to shorter utterances, and (d) initial breaths compared to final breaths. The implications of these findings for the neural control of breathing during speech are considered.

Acute respiratory acidosis: large-dose furosemide and cerebrospinal fluid ions

NaCl cotransport carrier is known to be involved in transepithelial fluid absorption and secretion in various tissues. Recent studies indicate that Na-K-2Cl cotransport carrier also exists in the choroid plexus cells and that inhibition of the carrier decreases cerebrospinal fluid (CSF) production. In this study, we used large-dose intravenous furosemide, an inhibitor of Na-K-2Cl carrier, to determine the effects on cisternal CSF ionic composition in acute respiratory acidosis. In pentobarbital-anesthetized mechanically ventilated dogs, renal pedicles were ligated to prevent furosemide-induced diuresis. The experimental group (group II, n = 7) received 400 mg/kg of furosemide intravenously, and group I (control group, n = 7) received the vehicle. In group II, serial serum and CSF furosemide concentrations were approximately 10(-3) and 10(-5) mol/l, respectively. During 5 h of acute respiratory acidosis in both groups, the mean arterial PCO2 increased approximately 25 Torr, with comparable changes in CSF PCO2. In both groups, CSF [HCO3-] and [H+] rose approximately 3 meq/l and 20 neq/l, respectively. Changes in CSF [Na+], [K+], [Cl-], and [Na(+)-Cl-] were also similar and were not significantly different from each other when the two groups were compared. These data show that furosemide at the dose that inhibits NaCl cotransport carrier does not significantly alter ionic composition of cisternal CSF.

Klippel-Feil syndrome associated with malformed larynx. Case report

We report a case of a 45-year-old man with Klippel-Feil syndrome with fusion of the C2-3 and C4-5 cervical vertebrae and severe voice impairment associated with malformation of the laryngeal cartilages. The condition was also complicated by bilateral inflexibility of the arms and legs and external malformation of the ears. This case broadens the spectrum of anomalies, of branchial arch derivation, now identified in association with Klippel-Feil syndrome. We discuss the possibility that perturbation of segmentation, distinct from somitogenesis, may be linked to Klippel-Feil syndrome-associated craniofacial abnormalities.

Recovery characteristics of desflurane versus halothane for maintenance of anesthesia in pediatric ambulatory patients

BACKGROUND

Desflurane is a new potent, inhaled anesthetic agent with low blood-gas solubility that should allow for the rapid induction of and emergence from anesthesia. However, its extreme pungency makes desflurane unacceptable for induction of anesthesia in children. This study was undertaken to determine the airway properties of desflurane administered by mask after anesthetic induction with halothane and nitrous oxide, and to compare the emergence and recovery properties of minimum alveolar concentration (MAC)-equivalent concentrations of desflurane or halothane in nitrous oxide in pediatric patients undergoing ambulatory surgery.

METHODS

Forty-five children undergoing ambulatory surgery for inguinal hernia repair, orchiopexy, and/or circumcision were randomized into two groups. Both groups were premedicated with intranasal midazolam and given halothane and nitrous oxide by mask to induce anesthesia. A caudal block was placed in children in both groups after anesthetic induction. For maintenance of anesthesia, group I patients (n = 22) were switched over to desflurane (1 MAC) and nitrous oxide, and group II patients (n = 23) continued to receive halothane (1 MAC) and nitrous oxide. All patients breathed spontaneously throughout the entire procedure, and all anesthetics were terminated abruptly at the conclusion of surgery. Recovery indicators (time to first response, length of time in the recovery room and length of time in the hospital) and the quality of the anesthetic emergence were assessed by a nurse blinded to each patient's anesthetic. This observer was present with the patient throughout his or her ambulatory hospitalization and continuously assessed the recovery indicators according to preset criteria.

RESULTS

The groups did not differ with respect to age, weight, or dose of midazolam. Although group I (desflurane) had a longer anesthesia time (52 +/- 12 min vs. 42 +/- 10 min), their time to first response (9.5 +/- 6.8 min vs. 20.9 +/- 14.7 min) and their recovery room time (21 +/- 10.7 min vs. 29 +/- 14.6 min) were less than those in group II (halothane). There was a trend for patient emergence from desflurane anesthesia to be associated with a higher incidence of emergence delirium (50% vs. 21%). The two groups were similar with respect to overall duration of postoperative ambulatory hospitalization.

CONCLUSIONS

In children premedicated with intranasal midazolam, desflurane maintenance anesthesia allows for a faster recovery. However, depending on the institution's criteria for ambulatory surgical patient discharge, desflurane may or may not affect the overall hospitalization time.

Retinoic acid inhibition of thyroxine binding to human transthyretin

All-trans retinoic acid is a potent inhibitor of [125I]-thyroxine (T4) binding to human erythrocyte membranes and can block the activation by thyroid hormone of erythrocyte Ca(2+)-ATPase [J. Biol. Chem. (1989) 264, 687-689]. In the present studies, retinoic acid was examined for its ability to displace thyroxine from binding sites on human transthyretin (TTR). Scatchard analysis of [125I]T4 binding to purified TTR, determined by equilibrium dialysis, revealed two classes of binding sites with association constants of 3.2 x 10(9) M-1 and 8.1 x 10(6) M-1. All-trans retinoic acid also displaced [125I]T4; 40% of the specifically bound [125I]T4 was displaced at a retinoic acid concentration of 2 x 10(-5) M. Analysis of the high affinity T4 binding site suggests that the Ka for retinoic acid to that site is approx. 10(7) M-1. 8-Anilinonaphthalene-1-sulfonate (ANS), a strongly fluorescing dye, binds to the thyroxine binding sites on TTR. T4 and 3,5,3'-L-triiodothyronine (T3) shifted the fluorescence emission maximum and intensity of an ANS-TTR solution toward the spectrum obtained from uncomplexed ANS. All-trans retinoic acid caused a similar shift in the emission spectrum of ANS, but was less potent than T4. Retinol failed to quench the emission intensity of the ANS-TTR complex, while 13-cis-retinoic acid was less effective than all-trans retinoic acid.

Assay and purification of Fv fragments in fermenter cultures: design and evaluation of generic binding reagents

Fv fragments whose genes have been cloned using common PCR primers carry identical peptide motifs at their termini. We have raised antibodies against the C-terminal motif of the VH chain GQGTTVTVSS and evaluated their utility as reagents for the assay and purification of Fvs in the fermenter culture. Three different Fvs were included in the investigation. We found that the motif was exposed and available for capture when Fv fragments were blotted onto nitrocellulose paper or adsorbed directly onto microtiter plates. In contrast, the motif was either partially or totally obscured when the Fv was complexed with immobilised antigen or when free in solution. This reactivity profile enabled us to develop a general-purpose assay for Fv protein, but not a general-purpose assay for monitoring active Fv. The apparent inaccessibility of the C-terminus of VH conflicts with currently held views on the three-dimensional structure of these molecules.

Rabbit skeletal muscle sarcoplasmic reticulum Ca(2+)-ATPase activity: stimulation in vitro by thyroid hormone analogues and bipyridines

Sarcoplasmic reticulum-enriched membranes from rabbit skeletal muscle contained Ca(2+)-ATPase activity which was significantly enhanced (26% increase, P < 0.001) in vitro by physiological concentrations (10(-10) M) of L-thyroxine (T4) and 3,3',5-triiodo-L-thyronine (T3). In contrast, the biologically inactive iodothyronine analogues D-T4 and 3,3',5,5'-tetraiodothyroacetic acid (Tetrac) (10(-10) M) were without effect on enzyme activity. 3,5-Dimethyl-3'-isopropyl-L-thyronine (Dimit), a bioactive analogue, was highly effective as a Ca(2+)-ATPase stimulator, increasing enzyme activity by 43% (P < 0.02 vs. T4 effect). A bipyridine cardiac inotropic agent, milrinone, has been reported to be thyromimetic in a myocardial membrane Ca(2+)-ATPase system, and in concentrations from 10(-10) to 10(-5) M enhanced skeletal muscle SR membrane Ca(2+)-ATPase activity in vitro (P < 0.001). Milrinone analogues which have been previously shown to enhance rabbit myocardial membrane Ca(2+)-ATPase activity, and which have a twist relationship of the pyridine rings, were also striated muscle Ca(2+)-ATPase stimulators. We conclude that (1) striated muscle is a mammalian tissue in which physiological levels of biologically relevant thyroid hormone analogues, particularly Dimit, stimulate Ca(2+)-ATPase activity in vitro by a non-genomic mechanism; (2) cardiac bipyridine analogues which are thyromimetic in vitro in rabbit heart, and which have structural homologies with thyroid hormone, are stimulators of rabbit striated muscle sarcoplasmic reticulum Ca(2+)-ATPase activity.

Cardiopulmonary bypass significantly reduces surfactant activity in children

Lung injury remains an important problem after cardiopulmonary bypass. The contribution of altered surfactant concentration or activity to pulmonary dysfunction after cardiopulmonary bypass is unclear. Recent evidence indicates that alveolar surfactant exists in specific aggregate forms that differ with respect to density, phospholipid composition, and function. A transition from surface active, higher density, large aggregates of surfactant to lower density, small aggregates that possess reduced surface activity has been demonstrated after experimental lung injury. The purpose of the present study was to examine surfactant aggregate fractions before and after bypass in children. Twelve acyanotic patients, aged 2 to 12 years, underwent intraoperative pulmonary function testing followed by bronchoalveolar lavage before incision and approximately 1 hour after termination of cardiopulmonary bypass. Saturated phosphatidylcholine pool sizes and total protein content of the small- and large-aggregate fractions of bronchoalveolar lavage fluid were determined. One hour after termination of cardiopulmonary bypass, the ratio of saturated phosphatidylcholine in small-aggregate as compared with that in large-aggregate fractions increased (mean +/- standard error) from 0.19 +/- 0.03 to 0.37 +/- 0.07 (p < 0.02), as did the ratio of saturated phosphatidylcholine to protein in the small-aggregate fraction (from 0.04 +/- 0.01 to 0.08 +/- 0.02, p < 0.05). Reductions in forced vital capacity (-19% +/- 5%), inspiratory capacity (-15% +/- 3%), and small airway flow rates (-32% +/- 6%) were also observed after bypass. These changes were accompanied by a fivefold increase in alveolar polymorphonuclear leukocyte content. The present study suggests that cardiopulmonary bypass of moderate duration in relatively healthy children is associated with surfactant changes that are similar in type and magnitude to those observed in experimental lung injury.

Inositol phosphates modulate binding of thyroid hormone to human red cell membranes in vitro

D-Myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and D-myo-inositol 4,5-bisphosphate (10(-6) mol/L) displaced specifically bound L-[125I] T4 from human erythrocyte membranes in vitro by up to 80%. D-Myo-inositol 1,3,4,5-tetrakisphosphate, D-myo-inositol 1-monophosphate, and D-myo-inositol 1,4-bisphosphate were ineffective in decreasing thyroid hormone binding to membranes. The effect of Ins(1,4,5)P3 on high affinity binding reflected a change in Kd (5.8 x 10(-11) vs. 1.5 x 10(-11) mol/L) and binding capacity (15 vs. 2 fmol/mg membrane protein) in the absence and presence of Ins(1,4,5)P3, respectively. Ins(1,4,5)P3 also displaced T3 from red cell membranes. Thus, selected inositol phosphates regulate the abundance of sites available for binding of thyroid hormone by human red cell membranes. This stereospecific action of inositol phosphates is among several plasma membrane effects recently described for these members of the signal-transducing phosphoinositide pathway.

Construction, characterisation and kinetics of a single chain antibody recognising the tumour associated antigen placental alkaline phosphatase

The murine monoclonal antibody H17E2 recognises placental alkaline phosphatase (PLAP), an antigen present in the human term placenta and also expressed by many tumours. The antibody is of value in both immunoscintigraphy and radioimmunotherapy in testicular and ovarian cancer. The small size of genetically engineered single chain antibodies (SCAs) should give diagnostic and therapeutic advantages of improved tumour penetration and increased blood clearance compared to IgG. Employing recombinant DNA techniques a SCA based on H17E2 has been expressed in Escherichia coli and has been shown to bind placental alkaline phosphatase specifically. When administered to nude mice bearing human tumour xenografts, the H17E2 SCA effectively localised to tumour whilst a co-administered non-specific SCA did not. H17E2 SCA achieves tumour: blood ratios that are superior to those achieved with whole IgG, probably owing to its rapid blood clearance. We conclude that the H17E2 SCA is suitable for further investigation as an agent for clinical imaging and therapy. Additionally, the SCA can also be used for the construction of antibody based fusion proteins to target other effector functions to tumour cells.

Microbial models of mammalian metabolism: involvement of cytochrome P450 in the N-demethylation of N-methylcarbazole by Cunninghamella echinulata

1. As previously reported (Yang and Davis 1992), N-methylcarbazole (NMC) is converted to N-hydroxymethylcarbazole (NHMC), and 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), two relatively stable carbinolamine metabolites by the fungus Cunninghamella echinulata (ATCC 9244). Decomposition of these two carbinolamines yields the corresponding dealkylated metabolites, carbazole and 3-hydroxycarbazole. In the present study, the possible involvement of cytochrome P450 in the requisite N-alkyl hydroxylation reaction was examined. 2. Carbon monoxide, a classical P450 inhibitor, markedly inhibited the formation of NHMC, as did potassium cyanide. 1-Benzylimidazole, piperonyl butoxide and SKF-525A inhibited the formation of both NHMC and 3-OH-NHMC, while beta-naphthoflavone (5,6-benzoflavone) induced their formation. 3. The source of the oxygen atom in the metabolite NHMC was examined by GC/MS analysis of NHMC formed during incubation of NMC in H218O-enriched medium which resulted in no incorporation of labelled oxygen into the metabolite. 4. An intermolecular isotope effect was not observed for the formation of NHMC suggesting that C-H bond cleavage is not a rate limiting step in the formation of this metabolite under the conditions examined. 5. It was concluded that P450 enzymes may be involved in the N-demethylation of NMC catalyzed by this fungal model of mammalian metabolism, and provides further support for biochemical and mechanistic parallels between mammalian metabolism and microbial systems catalyzing phase-1 biotransformations.

Effects of aging, diet, and sex on plasma glucose, fructosamine, and lipid concentrations in barrier-raised Fischer 344 rats

We studied the relationships of plasma glucose, fructosamine, triglycerides, and cholesterol as a function of age, gender, and diet in barrier-raised Fischer 344 rats aged 5 to 26 months, fed a diet either ad libitum or restricted to 60% of the ad libitum caloric intake. The complex relationships of these plasma levels to age, gender, and diet led to the development of a model with age, diet, and sex as covariates. Overall, fasting plasma glucose concentrations were reduced by approximately 25% in rats on the restricted diet, compared to ad libitum-fed animals. There was a significant age-dependent decline in glucose levels in male animals, whereas in females there was an increase in plasma glucose with aging. Plasma fructosamine levels in calorie-restricted animals, overall, were reduced by 7% compared to levels in animals fed ad libitum. There was a significant positive correlation between plasma glucose and fructosamine levels. Mean plasma triglyceride content was decreased by 50% in calorie-restricted rats compared to ad libitum-fed animals. A significant decrease in triglyceride levels with increasing age was seen in male animals, and an increase with aging in females. There was a significant positive correlation between plasma glucose and triglyceride levels. Plasma cholesterol levels in calorie-restricted animals were reduced by 7% compared to levels in ad libitum-fed animals. An increase of cholesterol concentration with aging was significant in both males and females. Analysis of the data showed that there were significant differences between male and female Fischer 344 rats in the response of plasma glucose and fructosamine to aging and calorie restriction. Changes of plasma triglyceride and cholesterol with aging and dietary calorie restriction were also different in males and females. Studies of the effect of aging on glycemia and blood lipid content should take into account the contributions of animal sex.

Acute cellular actions of thyroid hormone and myocardial function

The mechanisms of actions of thyroid hormone in various tissues are largely viewed as cell nucleus-mediated. However, several actions of this hormone are definitively extranuclear, and these include effects on the activities of Ca(2+)-adenosine triphosphatases (ATPases) of myocardial sarcolemma and, apparently, sarcoplasmic reticulum in animal models. Both effects would serve to reduce cytoplasmic (sarcoplasmic) [Ca2+]. Sarcoplasmic reticulum uptake of Ca2+ from sarcoplasm is mediated by Ca(2+)-ATPase and is deficient in end-stage heart failure; thyroid hormone can enhance sarcoplasmic reticulum Ca(2+)-ATPase activity acutely via an extranuclear mechanism or indirectly via the myosin-associated Ca(2+)-ATPase gene. Such actions would serve to improve myocardial relaxation, thus improvement in diastolic dysfunction, and may be cardioprotective if excessive levels of sarcoplasmic [Ca2+] develop during reperfusion of previously ischemic tissue. Action of thyroid hormone on sarcolemmal Ca(2+)-ATPase activity will enhance Ca2+ efflux, and a recently described effect of the hormone on myocardial Na+ inactivation current may serve to increase or reduce sarcoplasmic [Ca2+], depending upon the vector of Na+/Ca2+ exchange. This article reviews acute effects of thyroid hormone on the heart that are extranuclear in mechanism.

Congenitally missing permanent mandibular incisors and their association with missing primary teeth in the southern Chinese (Hong Kong)

A radiographic survey of a random sample of 454 girls aged 5.9 +/- 0.5 yr and 521 boys aged 5.8 +/- 0.4 y was undertaken to establish data on the incidence of congenitally missing mandibular incisor teeth amongst the Southern Chinese and to compare these figures with those of a similar previous study of 12-yr-olds so to eliminate factors such a trauma or extractions which may have artificially inflated the 12-yr-old incidence data. The proportion of 5-yr-old girls and boys affected by hypodontia in the permanent mandibular incisor region was 0.086 and 0.046 respectively (a significant difference between sexes, P < 0.02), compared with 0.047 and 0.034 for the 12-yr-olds (a non-significant difference) so other factors must have contributed to the discrepancy between the two groups of children. A very strong correlation (P < 10(-25)) between missing primary and missing permanent mandibular incisors is present in this group, and this has implications for prognosis and treatment planning. A fundamental developmental defect is implied.

Pulmonary and upper airway afferent influences on the motor pattern of vocalization evoked by excitation of the midbrain periaqueductal gray of the cat

It has been established previously that natural-sounding vocalization is evoked by excitation of the midbrain periaqueductal gray (PAG). It is not known, however, whether the motor output for such vocalization is invariant, or whether it is influenced by afferent discharge. We have investigated, in the unanesthetized precollicular decerebrate cat, the patterns of upper airway and respiratory EMG activity evoked by microinjection into the PAG of the excitatory amino acid D,L-homocysteic acid (6 to 40 nmol in 30-200 nl), under conditions of varied pulmonary and upper airway afferent input. The PAG-evoked pattern in the control state consisted of a 1- to 2-min sequence of episodic vocalizations (hiss or howl-like) with expiratory (vocalization) durations of generally less than 2 s, separated by one or more inspirations. During such PAG-evoked vocalization, a significant prolongation of the expiratory duration and an extended discharge in laryngeal, intercostal and abdominal muscles was evoked by the application of warm, humidified static air pressures (5-30 cm H2O) either: (i) to the lungs and tracheo-bronchial tree via a tracheostomy, or (ii) as an airflow through the upper airways in an expiratory direction. In contrast, if the development of the usual vocalization-related air pressures (5-45 cm H2O) in the lungs and airways was prevented by opening a tracheal cannula to the atmosphere, shortened respiratory durations (inspiratory and expiratory) occurred. The effects evoked by static pressure inflations of the lungs could be blocked by bilateral vagotomy or reversibly blocked by unilateral vagotomy combined with vagal cooling sufficient to abolish Hering-Breuer reflexes. These results indicate that the motor pattern for vocalization evoked by excitation of PAG is exquisitely sensitive to pulmonary and upper airway afferent input.

Microbial models of mammalian metabolism. Furosemide glucoside formation using the fungus Cunninghamella elegans

The diuretic furosemide (Lasix) was metabolized by the fungus Cunninghamella elegans (ATCC 36112) to the phase II conjugate, furosemide acyl glucoside. This metabolite was isolated following semipreparative scale incubations of C. elegans involving glucose nutrient dosing, and was characterized by NMR spectroscopy (1H and 1H/1H correlated), MS (FAB), UV, HPLC with fluorescence detection, and enzymatic treatments. The aglycone fragment of the conjugate was characterized as furosemide by treatment of the metabolite with sodium hydroxide, whereas the sugar part was identified as glucose by cleavage of the conjugate, derivatization of the released sugar, and GC/MS analysis.