A conserved disulfide motif in human tear lipocalins influences ligand binding.

Structural and functional characteristics of the disulfide motif have been determined for tear lipocalins, members of a novel group of proteins that carry lipids. Amino acid sequences for two of the six isolated isoforms were assigned by a comparison of molecular mass measurements with masses calculated from the cDNA-predicted protein sequence and available N-terminal protein sequence data. A third isoform was tentatively sequence assigned using the same criteria.

Effect of aging on A1-adenosine receptor-mediated inhibition of norepinephrine release in the rat heart.

Adenosine inhibits norepinephrine (NE) release from cardiac adrenergic nerves and reduces the postsynaptic beta-adrenergic mediated actions of NE, leading to decreased myocardial force of contraction. The actions of adenosine are mediated by pre- and postsynaptic adenosine A1 receptors (A1-AdoR). We reported that adenosine inhibition of postsynaptic beta-adrenergic receptor-mediated cyclic adenosine monophosphate (cAMP) production declines with age in male F344 rat hearts.

Phospholipase D hydrolyzes short-chain analogs of phosphatidylcholine in the absence of detergent.

Phospholipase D is an important enzyme in signal transduction in neuronal tissue. A variety of assays have been used to measure phospholipase D activity in vitro. The most typical measure of phospholipase D activity is the production of phosphatidylethanol in the presence of ethanol.

Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice.

Gap junction channels formed by alpha3 (Cx46) and alpha8 (Cx50) connexin provide pathways for communication between the fiber cells in the normal transparent lens. To determine the specific role of alpha3 connexin in vivo, the alpha3 connexin gene was disrupted in mice. Although the absence of alpha3 connexin had no obvious influence on the early stages of lens formation and the differentiation of lens fibers, mice homozygous for the disrupted alpha3 gene developed nuclear cataracts that were associated with the proteolysis of crystallins.

Subunit exchange of alphaA-crystallin.

alpha-Crystallin, the major protein in the mammalian lens, is a molecular chaperone that can bind denaturing proteins and prevent their aggregation. Like other structurally related small heat shock proteins, each alpha-crystallin molecule is composed of an average of 40 subunits that can undergo extensive reorganization. In this study we used fluorescence resonance energy transfer to monitor the rapid exchange of recombinant alpha-crystallin subunits.

Reduced adenosine A1 receptor and G alpha protein coupling in rat ventricular myocardium during aging.

Adenosine A1 receptor (A1-AdoR) function in rat ventricles has previously been shown to decrease with age. In the present study, using the ligand [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and coimmunoprecipitation of A1-AdoRs with their associated G proteins, we determined the specific binding of A1-AdoR and A1-AdoR/G protein coupling in ventricular myocardium of 6- to 24-month-old Fischer 344 rats. The densities (Bmax) of A1-AdoRs were 5.

Should laparoscopic appendectomy be avoided for complicated appendicitis in children?

Background/purpose: Laparoscopic appendectomy is becoming the preferred technique for treating acute appendicitis. However, recent literature on adults suggests that laparoscopic appendectomy may increase the risk for postoperative infectious complications in complicated (gangrenous or perforated) cases. This study was undertaken to compare the results of open versus laparoscopic appendectomy for complicated appendicitis in children.

Two roles for mu-crystallin: a lens structural protein in diurnal marsupials and a possible enzyme in mammalian retinas.

Purpose: micro-Crystallin is a major taxon-specific lens protein in some marsupials. Like other taxon-specific crystallins, it probably has another, non-crystallin role. Here we examine the distribution of mu-crystallin among species and its localization in the eye in placental mammals.

Ventricular fibrillation following blunt chest trauma from a baseball.

Objective: Baseball injuries account for a significant number of sports-related fatalities in children. We present a case of a 12-year-old male who died after being struck in the chest by a high velocity baseball propelled from a pitching machine. We examine the pathophysiology of blunt chest trauma, discuss possible explanations for the development of arrhythmias, review baseball-related fatalities, and suggest injury prevention strategies.

The effect of age on adenosine A1 receptor function in the rat heart.

Adenosine is an important regulatory metabolite in the heart where it has a cardioprotective function. In the ventricle, the cardioprotective action of adenosine is mediated through the adenosine A1 receptor and inhibition of adenylyl cyclase. In order to investigate the effect of age on adenosine signal transduction in the heart, the effect of specific adenosine A receptor agonists on adenylyl cyclase activity was measured in crude cardiac ventricular membranes isolated from 1-, 6- and 24-month-old Fisher 344 rats.

Importance of diarrhea as a presenting symptom of appendicitis in very young children.

Background: Appendicitis is an uncommon diagnosis in very young children. It is frequently complicated by delays in diagnosis, perforation, and lengthy hospital stays.

Objectives: To review our recent experience with appendicitis among children younger than 3 years old, and to identify the independent predictors of a prolonged hospital stay.

Discriminative stimulus effects of butorphanol: influence of training dose on the substitution patterns produced by Mu, Kappa and Delta opioid agonists.

The discriminative stimulus effects of butorphanol were examined in separate groups of pigeons trained to discriminate either a low (0.1 mg/kg), medium (1.0 mg/kg) or high (5.

Guanine nucleotide regulatory proteins, Gq and Gi1/2, mediate platelet-activating factor-stimulated phosphoinositide metabolism in immortalized hippocampal cells.

Platelet-activating factor (PAF) may be a neuromodulator involved in neural cell differentiation, cerebral inflammation, and ischemia. The PAF receptor is a member of the G protein-coupled receptor superfamily. In the present study, we sought to define the specific G protein(s) that mediate PAF-stimulated phosphoinositide (PI) metabolism in an immortalized hippocampal cell line, HN33.

Renal salvage procedures in patients with synchronous bilateral Wilms' tumors: a report from the National Wilms' Tumor Study Group.

Synchronous bilateral Wilms' tumor accounts for 4% to 6% of all Wilms' tumors. Renal salvage procedures (partial nephrectomy and enucleation) have been recommended to conserve renal parenchyma. The objective of this study was to review the results of renal salvage operations performed in children who had bilateral neoplasms.

Traumatic rupture of a wandering spleen in a child: case report and literature review.

A case of traumatic rupture of a wandering spleen in a 5-year-old girl is presented. To our knowledge, this is the first reported case of such injury in a child. The splenic injury was managed nonoperatively.

Characterization and enzyme activity of argininosuccinate lyase/delta-crystallin of the embryonic duck lens.

Argininosuccinate lyase (ASL)/delta-crystallin, a major soluble protein of the transparent eye lens of birds and reptiles, is a mixture of tetramers comprising all possible combinations of two similar polypeptides (delta 1 and delta 2). Only the delta 2 polypeptide has ASL activity. In the present investigation we have purified each of the 5 major isoforms (delta A to delta E, pI 5.

Supraumbilical skin-fold incision for pyloromyotomy.

We describe our experience with a supraumbilical skin-fold incision for pyloromyotomy in infants. Our technique uses a vertical fascial incision. This approach provides excellent exposure to the pylorus, allows greater operative flexibility, and results in a superior cosmetic outcome compared to the traditional right upper-quadrant incision.

Bronchogenic and esophageal duplication cyst in a single mediastinal mass in a child.

We report an unusual case of a mediastinal foregut malformation consisting of complete components of both a bronchogenic and an esophageal duplication cyst in a child. The lesion was identified as an incidental finding during evaluation of a clavicular fracture. Thoracotomy was performed for excision of the mass.

Identification and antitumor activity of a reduction product in the murine metabolism of pyrazoloacridine (NSC-366140).

Purpose: Pyrazoloacridine (PZA) is a newly developed anticancer agent currently undergoing clinical trials. Its mode of action has not been elucidated but the presence in its chemical structure of a 5-nitro functional group and its activity against oxygen-deficient cancerous cells argue in favor of enzymatic nitro reduction as a possible pathway for its antitumor activity. In order to assess the involvement of the nitro functionality in PZA activity, as well as to determine other metabolic products, a pharmacological and chemical study of PZA was designed.

Evidence that alpha-crystallin prevents non-specific protein aggregation in the intact eye lens.

The ocular lens is a transparent organ comprised of a highly concentrated and highly ordered matrix of structural proteins, called crystallins, which are probably the longest lived proteins of the body. Lens transparency is dependent upon maintenance of the short range order of the crystallin matrix. This transparency must be maintained for decades in the absence of normal protein synthesis or repair capacity.

Peroxynitrite-mediated inhibition of DOPA synthesis in PC12 cells.

Experimental evidence has implicated oxidative stress in the development of Parkinson's disease, amyotrophic lateral sclerosis, and other degenerative neuronal disorders. Recently, peroxynitrite, which is formed by the nearly diffusion-limited reaction of nitric oxide with superoxide, has been suggested to be a mediator of oxidant-induced cellular injury. The potential role of peroxynitrite in the pathology associated with Parkinson's disease was evaluated by examining its effect on DOPA synthesis in PC12 pheochromocytoma cells.