Toward a molecular understanding of congenital heart disease

BACKGROUND

This review discusses the incidence and importance of congenital heart disease (CHD), the reasons that investigation of causative mechanisms for human CHD has been slow, and the limitations of the multifactorial theory for the etiology of CHD.

METHODS AND RESULTS

The molecular defects underlying three vasculopathies--Marfan's syndrome (fibrillin), supravalvar aortic stenosis, and Williams' syndrome (elastin)--and hereditary telangiectasia are presented to emphasize the role of microfibrils and extracellular matrix in the pathophysiology of these vascular defects. Animal models of CHD, including situs inversus, canine conotruncal malformations, and chick neural crest ablation, are examined to emphasize how such studies relate to human CHD, especially by pointing to single-gene defects for conotruncal malformations, candidate loci for situs inversus, and phenotypic variability caused by neural crest lesions. The crucial role of cardiac transcription factors in heart morphogenesis is emphasized by review of gene knockout studies of these factors, which cause fetal death secondary to heart maldevelopment. Several lines of evidence demonstrating genetic etiologies of human CHD are also presented, including the mapping of familial atrial septal defects, to prove that one anatomic type of CHD may be due to single-gene defects at different loci. Review of atrioventricular canal, both secondary to trisomy 21 and as an autosomal-dominant familial defect, reiterates this conclusion. The evidence that monosomy on chromosome 22 causes multiple types of CHD, including aortic arch and conotruncal defects as part of the CATCH-22 syndrome, is presented, with results supporting the idea that deletions at this site alone may cause 5% of surgically treated CHD.

CONCLUSIONS

We conclude that (1) human CHD is frequently due to single-gene defects and that even sporadic defects may arise from a single-gene abnormality; (2) a common genetic defect may cause several apparently different forms of CHD; (3) elucidation of the genetic basis of CHD provides clues to normal cardiovascular developmental biology; (4) the same cardiac malformation can be caused by mutant genes at different loci; and (5) interactions of clinical investigators (cardiologists and cardiothoracic surgeons) with basic scientists should allow more rapid progress in defining the genetic basis of CHD.

Meningiomatosis cranii in childhood: a case report

Tumors of the meninges in infancy and childhood are unusual; childhood meningiomatosis is thought to be more common in neurocutaneous diseases. The case presented here is one of multiple recurrent and de novo benign meningeal tumors in a child who has no other signs or symptoms of a neurocutaneous syndrome.

Cloning of two rabbit GRO homologues and their expression in alveolar macrophages

We cloned two rabbit GRO homologue cDNAs from a lipopolysaccharide-stimulated rabbit alveolar macrophage (AM) cDNA library. One cDNA contains the complete coding sequence for a new mature GRO protein, RabGRO, which shares 68, 78 and 70% amino-acid identity with human GRO-alpha, -beta and -gamma, respectively. The other cDNA contains previously unreported sequence encoding a second GRO protein, rabbit permeability factor 2. The two Rab GRO proteins share 93% identity. Northern analysis shows that Rab AM GRO expression is rapidly induced by lipopolysaccharide. These findings suggest that GRO chemokines may be important in the pulmonary inflammation that occurs with septic lung injury.

Severe diffuse axonal injury in adults and children

Diffuse axonal injury (DAI) occurs in 30% of all fatal head injuries. DAI is identified on autopsy as microscopic lesions that commonly appear in the splenium of the corpus callosum, rostral brainstem and frontal and temporal lobes of the cerebrum. Clinical presentation of severe DAI includes patients with no lucid interval and decorticate or decerebrate posturing. Diagnostic studies describe concurrent pathologic anatomy associated with DAI. The most common mechanism for DAI is motor vehicle accidents. The neuroscience nurse needs to have an understanding of DAI anatomy and physiology, including the differences and similarities in the clinical presentation and neurologic functional outcome in both adult and pediatric populations.

Comparison of ventricular mass and function in early versus late repair of coarctation of the aorta

Left ventricular (LV) mass and function in 11 patients (group I) with coarctation of the aorta repaired at a mean age of 35 days were compared with that of 14 patients (group II) who underwent repair at a mean age of 8 years. Each group was compared to age- and sex-matched normal control subjects. All patients were normotensive and had resting arm-leg peak systolic blood pressure gradients < 20 mm Hg. Quantitative M-mode echocardiography was used to determine LV mass index and systolic performance. Magnetic resonance imaging was performed to assess residual narrowing of the descending aorta. LV mass index was increased in both groups when compared with control subjects (group I p = 0.01; group II p = 0.007). Whereas systolic performance in group I was similar to its control group, group II patients had enhanced LV systolic performance as measured by shortening fraction (p = 0.007). Multiple regression analysis of combined group I and II patients demonstrated a significant positive correlation of residual aortic narrowing with LV mass index (p = 0.01). Thus, LV mass remains increased in normotensive patients without major blood pressure gradients after repair of coarctation of the aorta in infancy or childhood. Small degrees of residual aortic narrowing were associated with increased postoperative LV mass regardless of the age at repair.

An investigation of habituation in the jellyfish Aurelia aurita

Three experiments were conducted to examine the effectiveness of different forms of tactile stimulation, probe and stream, and interstimulus intervals (ISI) in producing habituation in the polypoid sessile stage of the jellyfish Aurelia aurita. Results from Experiment 1 showed that polyps significantly decreased their responsiveness to both forms of tactile stimulation with 30-s ISI across 60 trials. Response to a novel stimulus indicated that the response decrement had not been due to fatigue. When the ISI was lengthened to 6 min in Experiment 2, response to the probe form of tactile stimulation did not significantly decrease across 20 trials. Using an ISI of 1 min in Experiment 3, response to the probe form of tactile stimulation decreased significantly across 40 trials. A significant increase in response to the original stimulus (dishabituation) following presentation of a novel stimulus indicated that response decrement was due to habituation or a habituation-like process rather than simple effector fatigue or sensory adaptation.

Multiple cervical spine fractures without neurologic deficit after a helicopter crash. Case report

The case of a soldier with multiple cervical fractures without neurologic deficit sustained after a helicopter crash during Operation Desert Storm is presented. The fractures involved the C2 body and the right facet joint and pedicle of C4. This fracture pattern, in association-with lack of neurologic deficit, is the first such case reported in the literature.

Repair of coarctation of the aorta in infancy: comparison of surgical and balloon angioplasty

Surgical repair of coarctation of the aorta in infancy has recently been challenged by some investigators who suggest that balloon angioplasty results in a lower mortality rate and similar risk of restenosis. Over a 44-month period, 37 consecutive infants with a mean age of 33 days (median, 15 days; range, 1 to 200 days) and mean and median weight of 3.7 kg (range, 2.4 to 5.4 kg) underwent surgical repair of coarctation of the aorta with either an end-to-end anastomosis (24 patients) or subclavian flap angioplasty (13 patients). There were no operative deaths (95% confidence interval, 0% to 10%). Four patients died late (> 30 days) after surgery (11%). Four patients (11%) (95% confidence interval, 3% to 25%) had residual gradients greater than 20 mm Hg. A review of the recent literature on treatment of native coarctation in infants with surgical repair (18 reports, 1189 patients) and balloon angioplasty (8 reports, 57 patients) reveals a similar early mortality rate but a much higher rate of recoarctation in infants who were treated with balloon dilation (57%) as compared with those who underwent surgical repair (14%). Because of the incidence of restenosis, balloon dilation as compared with surgical repair does not yet offer an improved outcome for native coarctation of the aorta in infancy.

Studies on the mechanism of the novel stimulatory effect of angiotensin-II on adenylate cyclase in rat fetal skin fibroblasts

In contrast to other systems in which angiotensin-II (AII) inhibits adenylyl cyclase, in fetal skin fibroblasts the peptide stimulates cAMP accumulation. The mechanism of this novel effect was studied by analysis of the actions of AII and other regulators on the adenylyl cyclase system in cultured cells. In the presence of phosphodiesterase inhibitors, AII, isoproterenol (ISO), choleratoxin (CTx), and forskolin (Fk) stimulated cAMP accumulation by 2.0 +/- 0.26-, 26 +/- 0.9-, 75 +/- 5.6-, and 88 +/- 3.3-fold, respectively. AII potentiated the stimulatory effect of ISO and CTx by 1.5 +/- 0.1- and 1.25 +/- 0.03-fold, respectively, but had no effect on that of Fk. Preincubation of the cells with PTx did not prevent the stimulatory effect of AII on basal and ISO- and CTx-stimulated cAMP, indicating that the effect of AII was not due to interaction with Gi. Unexpectedly, pretreatment of the cells with PTx for 18 h inhibited cAMP production stimulated by ISO and Fk. Similar inhibition by PTx was observed in adult rat skin fibroblasts, but not in adult human fibroblasts, in which pretreatment with PTx resulted in potentiation of Fk-stimulated cAMP production. ADP ribosylation studies showed that the optical density of the band corresponding to Gs was less than 20% that of Gi and Go in rat fetal cells, suggesting that excess release of the beta-gamma-subunit is responsible for the inhibition of cAMP production by PTx. However, immunoblot analysis of G-proteins showed that the content of Gs alpha was similar to that of Gi alpha and Go alpha in rat and human, fetal and adult cells. In contrast to the effect in intact cells, AII had no effect on basal or stimulated adenylyl cyclase activity in cell homogenates, suggesting that the stimulatory effect observed in intact cells is indirect. The stimulatory action of AII on cAMP production was not blocked by indomethacin, indicating that the effect is not mediated by prostaglandin formation. The stimulation of cAMP by AII was mimicked by 10-min incubation with phorbol 12-myristate 13-acetate (PMA), and prevented after cellular protein kinase-C (PKC) depletion by 4- or 6-h preincubation with PMA. However, the stimulation was not prevented by the PKC inhibitors staurosporine and H7 or 24-h preincubation with PMA, suggesting that the effect is not mediated by a traditional PKC-dependent mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)

Novel method to extract large amounts of bacteriocins from lactic acid bacteria

Antimicrobial peptides, bacteriocins, produced by lactic acid bacteria were adsorbed on the cells of producing strains and other gram-positive bacteria. pH was a crucial factor in determining the degree of adsorption of these peptides onto cell surfaces. In general, between 93 and 100% of the bacteriocin molecules were adsorbed at pHs near 6.0, and the lowest (< or = 5%) adsorption took place at pH 1.5 to 2.0. On the basis of this property, a novel isolation method was developed for bacteriocins from four genera of lactic acid bacteria. By using this method we made preparations of pediocin AcH, nisin, sakacin A, and leuconocin Lcm1 that were potent and concentrated. This method produced a higher yield than isolation procedures, which rely on precipitation of the bacteriocins from the cell-free culture liquor. It is simple and can be used to produce large quantities of bacteriocins from lactic acid bacteria to be used as food biopreservatives.

Klippel-Feil syndrome revisited: diagnostic pitfalls impacting neurosurgical management

Klippel-Feil syndrome in its most basic definition includes several anomalous conditions of the cervicomedullary junction and suboccipital region. Pediatric neurosurgeons are often involved in surgical palliation of this syndrome, without realizing how the accompanying anomalies may obfuscate management in the older child. A brief review of the embryology of the rhombencephalon helps to clarify the etiology of some of these symptoms which may cause confusion and, occasionally, inappropriate treatment. Illustrative cases will demonstrate some of these pitfalls. Appropriate early intervention, such as posterior fossa decompression, ventricular shunting, and fundal plication, may help to avoid needless morbidity. The advent of magnetic resonance scanning has helped to clarify the diagnosis and resulted in more appropriate treatment in these cases.

Nucleotide and amino acid sequence of pap-gene (pediocin AcH production) in Pediococcus acidilactici H

N-terminal analysis of purified pediocin AcH produced a partial sequence of 23 amino acids. This sequence matched perfectly with a segment of 23 amino acids in a 62 amino acid molecule generated from the 186 nucleotide sequence open reading frame in a Hind III fragment in pSMB74 encoding pap-gene (pediocin AcH production). It is suggested that the molecule is translated as inactive prepediocin AcH of 62 amino acids. Then through enzymatic modifications the leader segment of 18 amino acids is removed from the NH2-terminal. The remaining segment of 44 amino acids is active pediocin AcH of 4628 M(r).

Inhibition of Listeria spp. in Sterile Food Systems By Pediocin AcH, a Bacteriocin Produced By Pediococcus acidilactici H

The effectiveness of pediocin AcH, a bacteriocin produced by Pediococcus acidilactici H, in reducing population levels and growth of Listeria monocytogenes strains and Listeria ivanovii in sterile ground beef, sausage mix, cottage cheese, ice cream, and reconstituted dry milk was examined. Predetermined numbers of Listeria cells and concentrations of pediocin AcH were added to the foods suspended in water and the final volumes made to 10 ml. Listeria in the pediocin AcH treated and control samples during storage at 4 and 10°C were enumerated as CFU on tryptic soy agar. Results indicated that: (a) the maximum bactericidal action of pediocin AcH occurred within 1 h and was not interfered with by the foods; (b) Listeria strains differed in sensitivity to pediocin AcH; (c) reduction in CFU was greater with higher levels of pediocin AcH and as the initial cell number of Listeria spp. decreased; and (d) the surviving cells in pediocin AcH treated food samples multiplied in the presence of residual pediocin AcH during storage at 4 and 10°C.

Angiotensin-II receptor subtypes and coupling to signaling systems in cultured fetal fibroblasts

Angiotensin-II (AII) receptors and their coupling to signaling transduction systems were studied in fetal skin fibroblasts using the receptor subtype-specific antagonists Dup753 (type 1) and PD123177 (type 2). In primary cultures, total binding per cell remained constant from days 2-6 of culture, but after subculture levels were initially decreased, then increased until the cells reached confluence. In freshly isolated cells more than 90% of the receptors were type 2, and only a minor fraction were type 1, findings that are consistent with autoradiographic analyses and membrane binding assays. The proportions tended to reverse during culture, with type 1 receptors accounting for 60-80% and type 2 for 20-40% by day 6 of culture. In secondary culture, subtype 1 was about 50% on day 1 and increased to 70% by day 6. At subsequent passages, the proportion of receptor subtypes remained constant up to 6 days, with 90% being of the type 1 variety and 10% of type 2. Scatchard analysis of binding in the presence of the selective antagonists showed similar binding affinities for both subtypes, and the changes in receptor subtype during culture were due primarily to changes in receptor number. Treatment of primary cultures with actinomycin-D for 24 h prevented the transition from AII receptor type 2 to type 1 by increasing the absolute number of type 2 receptors, suggesting that receptor synthesis is regulated at the posttranscriptional level. Stimulation of the cells with 100 nM AII resulted in increases in inositol phosphate accumulation, an effect that was prevented by the type 1 antagonist, but not by the type 2 antagonist. In contrast with other systems in which AII inhibits adenylate cyclase, in fetal fibroblasts AII stimulate cAMP production. The increases in cAMP were more pronounced in secondary cultures in which type 1 receptor content is higher, and the effect was prevented by the type 1, but not the type 2, antagonists. These findings demonstrate the presence of both AII receptor subtypes in fetal fibroblasts, but only the type 1 receptors are coupled to a known intracellular signalling system. The changes in AII receptor subtypes may be the consequence of alterations in intercellular communication, endocrine, or paracrine factors during culture.

The role of fitness on VO2 and VCO2 kinetics in response to proportional step increases in work rate

The purpose of this study was to determine the effect of fitness and work level on the O2 uptake and CO2 output kinetics when the increase in work rate step is adjusted to the subject's maximum work capacity. Nine normal male subjects performed progressive incremental cycle ergometer exercise tests in 3-min steps to their maximum tolerance. The work rate step size was selected so that the symptom-limited maximum work rate would be reached in four steps at 12 min in all subjects. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were calculated breath by breath. For the group, the time (mean, SEM) to reach 75% of the 3-min response (T0.75) for VO2 increased significantly (P less than 0.01) at progressively higher work rate steps, being 53.3 (5.5) s, 63.5 (4.6) s, 79.5 (5.0) s, and 94.5 (5.8) s, respectively. In contrast, T0.75 for VCO2 did not change significantly [74.9 (7.4) s, 75.6 (5.0) s, 85.1 (5.3) s, and 89.4 (6.3) s, respectively]. VCO2 kinetics were slower than VO2 kinetics at the low fractions of the subjects' work capacities but were the same or faster at the high fractions because of the slowing of VO2 kinetics. The first step showed the fastest rise in VO2. While VO2 kinetics slowed at each step, they were faster at each fraction of the work capacity in the fitter subjects. The step pattern in VO2 disappeared at high work rates for the less fit subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of exercise testing protocol on parameters of aerobic function

Four different patterns of increasing work rate (ramp and 1-min, 2-min, and 3-min steps) to maximum tolerance were studied in eight normal male subjects during cycle ergometer exercise testing to determine the effect of the work rate protocol on the parameters of aerobic function. The overall rate of work rate increase was kept constant. Measurements included VO2max, anaerobic threshold (AT), and the O2 uptake increase with respect to work rate increase (delta VO2/delta WR). VO2, VCO2, VE, respiratory exchange ratio (R), PETCO2, and PETO2 were calculated breath-by-breath. No significant difference was found in VO2max, AT, AT/VO2max, and delta VO2/delta WR among the four work rate protocols. Other measurements such as total work, maximal work rate, VCO2, VE, R, HR, O2 pulse, and the VO2 at which VE increases disproportionately to VCO2 (ventilatory compensation point) were also similar among the four protocols. Both the ramp and 1-min step work rate tests had no step pattern in either VO2 or VCO2, and the step pattern for the 2-min and 3-min step tests was attenuated or disappeared at work rates above AT. We conclude that the parameters of aerobic function, and other physiological responses at maximum work rate, were independent of the pattern of work rate increase, provided that the overall rate of work rate increase was the same.

Persistence of fetal bovine serum proteins in human keratinocytes

Cultured human keratinocytes are used for skin grafts, but their success is limited by late graft loss. Development of antibody to fetal bovine serum (FBS) protein used in culture media for in vitro keratinocyte growth has been identified. The persistence of FBS antigen in skin grafts is important in the induction of the immune response and the susceptibility of the keratinocytes to immune-mediated injury. The magnitude and longevity of FBS protein persistence on human keratinocytes was studied. Secondary passage human keratinocytes were grown in media supplemented with 5% FBS. The media was changed to one supplemented with pooled human AB serum, and the amount of FBS protein incorporated in the tissue was measured over the following 8 days by an ELISA reaction directed against FBS antigen. Incorporated FBS antigen decreased for the first 3 days to 31% of maximum. There was no further significant decrease for 5 days. Keratinocytes grown in alternative serum supplements (NuSerum [Collaborative Research Inc., Bedford, Mass.] and Serum Plus [Hazelton Research Products Inc., Lenexa, Kan.]), which contain reduced amounts of FBS, offered no significant reduction in FBS protein incorporation. This duration of antigen persistence would make human keratinocytes susceptible to cell destruction by immune response to FBS and may contribute to delayed loss of human keratinocyte grafts.

Antigenic property of pediocin AcH produced by Pediococcus acidilactici H

Pediocin AcH, a bacteriocin of Pediococcus acidilactici H, inhibits the growth of several food spoilage and pathogenic bacteria. The antigenic property of partially purified pediocin AcH was tested by immunizing mice and a rabbit. Pediocin AcH was not immunogenic in these animals as determined by immunoblotting even after conjugation to bovine serum albumin. The non-immunogenic nature of pediocin AcH, its non-toxicity to laboratory animals and its hydrolysis by gastric proteolytic enzymes may be considered favourably in its possible use as a food preservative.

Chronic ethanol exposure before injury produces greater immune dysfunction after thermal injury in rats

Chronic alcoholics constitute a small but significant subgroup of burned patients. The effects of chronic alcohol exposure on immune function in burned patients has not to our knowledge been studied. This study was designed to determine the effect of chronic alcohol exposure before burn injury on immune function after injury in rats. Immune function assessed by in vivo chemotaxis and responsiveness of non-adherent splenocytes to both a T-cell mitogen, concanavalin A, and a B-cell mitogen, lipopolysaccharide, was measured at 4 days after a 20% BSA full-thickness burn injury and/or gavage of 2.4 gm/kg/day of ethanol for 14 days. Chronic ethanol ingestion before burn injury produced significant suppression in chemotaxis and response to lipopolysaccharide but not in response to concanavalin A. These results suggest that chronic alcohol exposure before injury can contribute to further impaired immune function after injury, and may lead to increased susceptibility to infection and increased mortality.

Estimates of psychological distress among Vietnamese refugees: adolescents, unaccompanied minors and young adults

This study focuses on the assessment of psychological distress among three subgroups of Vietnamese refugee youth: adolescents, unaccompanied minors, and young adults. Using translated and backtranslated instruments, data was gathered in refugee camps in the Philippines in order to provide baseline measurement for future comparisons, as well as to begin to develop normative standards for these populations. A rationale for the choice of instruments (Vietnamese Depression Scale, Hopkins Symptom Checklist-25 and General Health Questionnaire) is offered and mean scores and percentages scoring above established clinical cut-offs are presented. Results indicate relatively high levels of depression and anxiety for the young adult group, although anxiety appeared high across all three groups. All three groups also scored poorly on self-reports of general health, with the young adults and unaccompanied minors being especially overrepresented in the clinical range. Significant method problems were noted regarding construct validity in the assessment of depression, and instructional set differences that may account for the relatively low intercorrelations between seemingly similar measures.

Immunologic consequences of acute ethanol ingestion in rats

Acute ethanol (EtOH) intoxication is commonly associated with many medical and surgical problems which primarily or secondarily involve infection. Chronic EtOH ingestion has been associated with immune dysfunction and an increased risk of infection; however, the relationship of acute EtOH exposure and immune function has not been clearly defined. To determine if there is a relationship between acute EtOH intoxication and immune function, the effects of a single EtOH ingestion on immune function were studied in a rat model. Acute intoxication was produced by gavage feeding of 3 g/kg of EtOH, and immune function was evaluated by in vivo chemotaxis to a chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine and responsiveness of splenic lymphocytes to B- and T-cell mitogens. Chemotaxis was significantly suppressed at 4 hr (49.0 +/- 5.1% of control) after EtOH ingestion (P = 0.001), but returned to normal by 24 hr and remained at that level. However, acute EtOH ingestion showed no suppressive effects on lymphocyte responsiveness to either concanavalin A or LPS. These results indicate that a single ingestion of EtOH has the potential to transiently suppress chemotactic function of granulocytes but not affect lymphocyte mitogenic responsiveness in rats. This potential may contribute to increased susceptibility to infection in patients after EtOH ingestion.