Distribution of abnormal karyotypes among malformed fetuses detected by ultrasound throughout gestation

The participation of sarcoplasmic reticulum Ca2+ release channels in the activation of Ca(2+)-sensitive K+ currents (IK(Ca)) by cyclic dibutyryl GMP was investigated in smooth muscle cells from the circular layer of guinea-pig gastric fundus. All experiments were performed in the presence of 3 microM nicardipine into the bath and low Ca2+ buffering capacity of the pipette-filling solution (pCa 7.4). Ruthenium red (10 microM) as well as its combination with 10 microM heparin abolished the cyclic GMP-induced activation of IK(Ca), while 10 microM heparin remained ineffective. Ryanodine (10 microM) and the subsequently added 1 microM thapsigargin induced a relatively small increase in IK(Ca) amplitudes. The addition of 10 microM ryanodine to 1 microM thapsigargin-containing bath solution caused a vast increase in IK(Ca). It is hypothesyzed that protein kinase G-induced vectorial Ca2+ flux from the cell bulk and sarcoplasmic reticulum Ca2+ stores toward the plasma membrane is realized by a spontaneous Ca(2+)-induced Ca2+ release from a superficially situated Ca2+ store.     

Epithelial marker genes are expressed in cultured embryonic rat lung and in vivo with similar spatial and temporal patterns

Explants of embryonic lung are often used to characterize lung growth, bronchial tree pattern, and cell differentiation. Most investigators culture lungs for 3-7 days in defined media lacking, e.g., added growth factors or hormones. If growth and differentiation are comparable to that in vivo, these cultures show considerable promise for identifying developmental regulatory molecules and target genes, and for elucidating molecular responses. We used in situ hybridization and RT-PCR to compare times and sites of expression of mRNAs of six epithelial genes in cultured and uncultured fetal rat lungs. These genes, expressed in distal lung of adult rats, are surfactant proteins (SP) A, B, and C; LAR, a receptor-type tyrosine phosphatase; Clara cell secretory protein (CC10, CCSP); and T1alpha. SP-A, SF-B, LAR, and CC10 are expressed by both Clara and Type II cells in adult animals. SP-C and T1alpha are unique markers for Type II and Type I cells, respectively. SP-C, LAR, and T1alpha are expressed before the lung is explanted (Day 13.5); SP-A, -B, and CC10 mRNAs are first detected later. The onset of expression is similar in vivo and in vitro. Although the patterns of expression differ for each mRNA, their sites of expression in culture match those in vivo relative to the bronchial tree. The explanted embryonic lung appears to be an excellent experimental model.     

Age-dependent effects of muscle vibration and the Jendrassik maneuver on the patellar tendon reflex response

OBJECTIVE: To explore possible effects of aging on the excitability of spinal reflexes. DESIGN: Using a cross-sectional design, the influences of muscle vibration and the Jendrassik maneuver on patellar tendon reflex function were compared between 30 young adults and 15 older adults. SETTING: Motor control research laboratory. SUBJECTS: The young adults were volunteers of college age. The older adults (74.5 +/- 4.14 yr) were volunteers from the local community. All subjects were free of medications and neurological conditions that would affect normal neuromuscular responses. MAIN OUTCOME MEASURES: A force-time curve analysis of the patellar tendon reflex response was used to assess the inhibition and facilitation of spinal reflexes. In the experimental protocol to assess spinal reflex inhibition, 100 Hz vibration was applied to the right quadriceps muscle. In another experimental protocol, spinal reflex facilitation was assessed using the Jendrassik maneuver. To perform the Jendrassik maneuver, subjects were instructed to grasp their hands together and to pull as hard as possible while breathing normally. After a 2-second count, the tendon tap was delivered to the right leg and the subject was instructed to relax. In both experimental protocols, control patellar tendon reflexes were collected. RESULTS: Analysis of variance for reflex peak force revealed a significant 30% reduction in the amount of vibration-induced reflex inhibition with increasing age, and a similar 33% reduction in the amount of Jendrassik maneuver facilitation observed for the older adults as compared with the younger adults. CONCLUSION: These results support the hypothesis that inhibitory and excitatory influences acting on the alpha motoneuron pool are different in young and older adults.     

Interpretation of the complete blood count

The authors' impression is that the CBC provides much more information than is routinely used. When anemia is present, the CBC contains considerable information regarding its cause, which can assist in formulating a differential diagnosis and directing further evaluation. White blood cell and platelet count levels may similarly direct practitioners to consider or dismiss underlying conditions. This article assists the pediatrician in optimizing use of this familiar diagnostic tool.     

Prenatal ultrasonic diagnosis of obstructive bowel disease: a retrospective analysis

Fetal obstructive bowel disease was diagnosed in 29 patients at 22-37 weeks (median 32 weeks) of gestation, seven (24 per cent) of whom also displayed other anomalies. Polyhydramnios was present in 20/29 cases (69 per cent). An abnormal karyotype existed in 7/29 cases (24 per cent), of which six were diagnosed prenatally (trisomy 21, n = 5; 69,XXX, n = 1) and one postnatally (trisomy 21). There was always an association with the ultrasonic 'double bubble' sign. Obstructive bowel disease was confirmed postnatally in 20/29 (69 per cent) cases, i.e., oesophageal atresia (n = 1), duodenal obstruction (n = 12), and small bowel obstruction (n = 7). Other anomalies existed in 6/29 (21 per cent) cases, i.e., multicystic kidney (n = 1) and multiple congenital anomalies (n = 5). The perinatal mortality rate was 35 per cent (7/20).     

Accidents with sharp instruments in nurses in a university hospital in Campinas, Sao Paolo

To investigate the role of the sympathetic nervous system in angiotensin II (AngII)-stimulated medial and neointimal smooth muscle cell (SMC) replication, we sympathectomized rats with 6-hydroxydopamine (6-OHDA) in which the left carotid artery was injured by a balloon catheter. Balloon injury is associated with a loss of specific [3H]-prazosin binding. AngII (250 ng/kg/min), infused 2 weeks after balloon injury of the rat left carotid artery, increased systolic blood pressure by approximately 70 mm Hg. There was no effect of 6-OHDA on this pressor response. AngII increased the cumulative 5-bromo-2'-deoxyuridine (BrdU) labeling fraction (LF) in the uninjured right carotid media and the injured left carotid neointima as compared to controls (5.7+/-1.6% vs. 0.4+/-0.1%, p<0.05; 10.6+/-0.9% vs. 5.0+/-0.8%, p<0.05, respectively). 6-OHDA decreased the AngII-induced increase in LF in the media of the uninjured right carotid artery (AngII/6-OHDA 0.9+/-0.2% vs. AngII 5.7+/-1.6%, p < 0.05). 6-OHDA did not decrease the AngII-induced increase in LF in both the injured left carotid media and neointima at 4 weeks after balloon injury. The effects of chemical sympathectomy were comparable with those obtained 12 weeks after balloon injury. Thus, the data show that the sympathetic nervous system mediates the AngII-induced increase in SMC DNA synthesis, but only in the uninjured carotid media. This indicates a differential regulation of AngII-induced SMC replication in injured and uninjured vessels.     

Regulation in the heart field of zebrafish

In many vertebrates, removal of early embryonic heart precursors can be repaired, leaving the heart and embryo without visible deficit. One possibility is that this 'regulation' involves a cell fate switch whereby cells, perhaps in regions surrounding normal progenitors, are redirected to the heart cell fate. However, the lineage and spatial relationships between cells that are normal heart progenitors and those that can assume that role after injury are not known, nor are their molecular distinctions. We have adapted a laser-activated technique to label single or small patches of cells in the lateral plate mesoderm of the zebrafish and to track their subsequent lineage. We find that the heart precursor cells are clustered in a region adjacent to the prechordal plate, just anterior to the notochord tip. Complete unilateral ablation of all heart precursors with a laser does not disrupt heart development, if performed before the 18-somite stage. By combining extirpation of the heart precursors with cell labeling, we find that cells anterior to the normal cardiogenic compartments constitute the source of regulatory cells that compensate for the loss of the progenitors. One of the earliest embryonic markers of the premyocardial cells is the divergent homeodomain gene, Nkx2.5. Interestingly, normal cardiogenic progenitors derive from only the anterior half of the Nkx2.5-expressing region in the lateral plate mesoderm. The posterior half, adjacent to the notochord, does not include cardiac progenitors and the posterior Nkx2.5-expressing cells do not contribute to the heart, even after ablation of the normal cardiogenic region. The cells that can acquire a cardiac cell fate after injury to the normal progenitors also reside near the prechordal plate, but anterior to the Nkx2.5-expressing domain. Normally they give rise to head mesenchyme. They share with cardiac progenitors early expression of GATA 4. The location of the different elements of the cardiac field, and their response to injury, suggests that the prechordal plate supports and/or the notochord suppresses the cardiac fate.