Birth weight and cardiovascular malformations: a population-based study. The Baltimore-Washington Infant Study

Mean birth weights were evaluated in infants with D-transposition of the great arteries, tetralogy of Fallot, endocardial cushion defect, hypoplastic left heart syndrome, pulmonary stenosis, aortic stenosis, coarctation of the aorta, ventricular septal defect, and atrial septal defect in a population-based case-control study of congenital cardiovascular malformations in residents of Maryland, Washington, D.C., and northern Virginia (1981-1987). Study subjects were liveborn singletons without extracardiac anomalies. After adjustment for potentially confounding maternal, gestational, and infant factors, significant birth weight deficits were found for infants with tetralogy of Fallot, endocardial cushion defect, hypoplastic left heart syndrome, pulmonary stenosis, coarctation of the aorta, ventricular septal defect, and atrial septal defect. After adjustment, infants with these malformations (except coarctation of the aorta and atrial septal defect) were also significantly more likely than were controls to have low birth weight for gestational age. These findings strengthen previous evidence that certain cardiovascular malformations and low birth weight may be causally related.

Aberrant epithelial cell growth in autosomal dominant polycystic kidney disease

Renal cyst enlargement in autosomal dominant polycystic kidney disease (ADPKD) is characterized by increased epithelial cell proliferation and fluid accumulation. Using monolayer epithelial cultures derived from individually microdissected human ADPKD cysts and immunolocalization studies in vivo, the roles of matrix and growth factors in aberrant ADPKD cell proliferation have been studied. Abnormal ADPKD basement membrane ultrastructure was associated with increased turnover of 35S-labeled heparan sulfate proteoglycans (HSPG) by comparison to normal renal tubule epithelia in vitro. Mitogenic assays demonstrated significant increase in 3H-thymidine incorporation into ADPKD epithelia grown on type I and type IV collagen by comparison to normal proximal straight tubules (PST), collecting ducts, and thick ascending limbs of Henle (TAL). Proliferation on laminin or fibronectin matrices was unchanged and immunolocalization of matrix proteins was polarized and restricted to basal membranes of both ADPKD cysts and renal tubule epithelia in vivo. ADPKD epithelia in vitro were hypersensitive to the mitogenic action of epidermal growth factor (EGF) and EGF immunoreactivity was detected in ADPKD cyst lining epithelia, in cyst fluid, and in conditioned media from confluent ADPKD cultures, suggesting an autocrine mechanism of growth regulation. In addition, inhibition of epithelial proliferation by transforming growth factor-beta (TGF-beta), which was 100% in normal renal tubule epithelia, was reduced to 41% in ADPKD epithelia.

A relationship between multidrug resistance and growth-state dependent cytotoxicity of the lysosomotropic detergent N-dodecylimidazole

Multidrug resistance (MDR) in cultured cells and tumors is associated with overproduction of P-glycoprotein, a plasma membrane efflux pump normally present at very low levels. The cytotoxic action of N-dodecylimidazole (C12-Im), a lysosomotropic detergent, on cultured cells was previously shown to be strongly dependent on growth state, with rapidly growing cells being most sensitive and confluent cells most resistant. We show here that this may be due to a growth dependent increase in cellular P-glycoprotein activity. Both verapamil and nifedipine, structurally unrelated P-glycoprotein inhibitors, increased markedly the sensitivity of CHO fibroblasts to killing by C12-Im; the increase was greater in confluent than in growing cells. Also, verapamil inhibitable 3H-daunomycin efflux was more efficient from confluent than from subconfluent cells. The MDR cell line CH(R)C5 differed from all cell lines previously examined in that it did not show a growth-dependent decrease in C12-Im sensitivity, and sensitivity was not increased by verapamil or nifedipine. We suggest that a growth-dependent increase in MDR activity is a general property of cultured cells, except for those specifically overexpressing P-glycoprotein.

Reversed polarity of Na(+) -K(+) -ATPase: mislocation to apical plasma membranes in polycystic kidney disease epithelia

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder in which renal tubules become enormously enlarged due to fluid accumulation. Na(+) -K(+) -ATPase was compared in normal and cystic regions of whole kidneys and in confluent primary cultures of microdissected renal tubule and cyst-lining epithelia. Immunostaining with antibodies directed against the Na(+) -K(+) -ATPase catalytic alpha-subunit was confined to apical, luminal plasma membranes of ADPKD epithelia, which was a complete reversal of the normal renal tubule polarized location in basolateral membranes. Mislocated Na(+) -K(+) -ATPase was shown to be functionally active, because identical intense apical staining was observed by use of a cytochemical assay. In addition, biochemical assays showed a significant increase in these ouabain-inhibitable Na(+) -K(+) -ATPase specific activity levels in ADPKD kidneys compared with age-matched normal kidneys. Specific binding of [3H] ouabain was not only increased but also confined to the apical membrane vesicles prepared from cystic regions of ADPKD kidneys compared with normal age-matched controls, in which binding was confined to basolateral membrane vesicles. Although steady-state levels of Na(+) -K(+) -ATPase alpha- and beta-subunit in mRNAs were increased somewhat in ADPKD kidneys, this alone was not sufficient to account for the observed activation. Confluent ADPKD epithelia grown on dual-chamber, permeable membrane supports also showed reversed polarity of 22NaCl vectorial transport, because this was from basal to apical media compartments. Because this transport could also be blocked by ouabain, this suggested apical Na(+) -K(+) -ATPase was responsible and implicated altered polarity of Na(+) -K(+) -ATPase and resultant Na+ secretion as a mechanism for cyst formation in ADPKD. Because no reversal of polarity of other basolateral or apical membrane proteins was detected, an intracellular sorting defect specific for Na(+) -K(+) -ATPase is proposed.

Automated real-time data acquisition and analysis of cardiorespiratory function

Microcomputer generation of an automated record without complexity or operator intervention is desirable in many circumstances. We developed a microcomputer system specifically designed for simplified automated collection of cardiorespiratory data in research and clinical environments. We tested the system during possible extreme clinical conditions by comparison with a patient simulator. Ranges used were heart rate of 35-182 beats per minute, systemic blood pressures of 65-147 mmHg and venous blood pressures of 14-37 mmHg, all with superimposed respiratory variation of 0-24 mmHg. We also tested multiple electrocardiographic dysrhythmias. The results showed that there were no clinically relevant differences in vascular pressures, heart rate, and other variables between computer processed and simulator values. Manually and computer recorded physiological variables were compared to simulator values and the results show that computer values were more accurate. The system was used routinely in 21 animal research experiments over a 4 month period employing a total of 270 collection periods. The file system integrity was tested and found to be satisfactory, even during power failures. Unlike other data collection systems this one (1) requires little or no operator intervention and training, (2) has been rigorously tested for accuracy using a wide variety of extreme patient conditions, (3) has had computer derived values measured against a standardized reference, (4) is reliable against external sources of computer failure, and (5) has screen and printout presentations with quick and easily understandable formats.

Dependencies of respiratory system resistance and elastance on amplitude and frequency in the normal range of breathing

We calculated respiratory system resistance (Rrs) and elastance (Ers) from pressure and flow at the mouth in six seated subjects relaxed at FRC (cheeks tightly compressed) during sinusoidal volume forcing (250, 500, and 750 ml) at 0.2, 0.4, and 0.6 Hz. Dependencies of Rrs and Ers on frequency and tidal volume were generally the same in each subject; Rrs tended to decrease with frequency and tidal volume, whereas Ers tended to increase with frequency and decrease with tidal volume. Multiple linear regression of combined data indicated that the frequency and tidal volume effects on Rrs and Ers were significant (p less than 0.05), and that the effects on Rrs decreased at higher flows. Average Rrs was highest (4.43 cm H2O/L/s +/- 0.21 SE) at 0.2 Hz-250 ml, and lowest (3.07 cm H2O/L/s +/- 0.37) at 0.6 Hz-750 ml. Average Ers was highest (12.1 cm H2O/L +/- 1.1) at 0.6 Hz-250 ml, and lowest (7.1 cm H2O/L +/- 0.6) at 0.2 Hz-750 ml. We conclude that frequency and tidal volume dependencies in Rrs and Ers in the normal range of breathing should be considered when interpreting measurements of respiratory system impedance or developing models to describe the mechanical behavior of the respiratory system.

Teratogenicity of 2-methoxyethanol applied as a single dermal dose to rats

2-Methoxyethanol (2-ME) was applied as a single dermal dose on the backs of collared, pregnant Sprague-Dawley rats on Gestation Days (GD) 10, 11, 12, 13, or 14 at doses of 0 and 2000 mg/kg, and at doses of 0, 250, 500, and 1000 mg/kg on GD 12. Except for a transient loss in body weight observed the day after 2-ME administration, no signs of maternal toxicity were observed. On GD 20, dams were necropsied and the fetuses evaluated for normal development. Resorptions were significantly (p less than 0.05) increased in dams exposed to 2-ME on GD 10. Fetal body weights were reduced at dose levels of 1000 and 2000 mg/kg, but statistically significant differences were found only on GD 10 and 12. Significant increases in external, visceral, and skeletal malformations were observed in fetuses exposed to 2-ME at dose levels of 500 mg/kg or greater. Defects of the cardiovascular and urinary systems were the prominent visceral malformations observed. Limb defects (especially those pertaining to the digits) and vertebral column defects (primarily of the tail) were the most frequently observed skeletal defects. At the 2000 mg/kg dose level, 2-ME was teratogenic regardless of the GD of administration. Based on the results of this study, the no observed adverse effect level for developmental toxicity for a single dermal dose of 2-ME applied on GD 12 was determined to be 250 mg/kg.

Acetabular reconstruction with a bipolar prosthesis and morseled bone grafts

The results of eighteen acetabular reconstructions in which a bipolar prosthesis and morseled bone grafts were used for a major acetabular defect were evaluated. Thirteen Type-II (cavitary) and five Type-III (combined) acetabular deficits were treated. All of the patients were followed for at least two years. The procedure failed in eleven patients: six had radiographic evidence of complete resorption of the bone grafts and migration of the acetabular component; three, deep infection; one, recurrent dislocation; and one, pain of undetermined cause despite a satisfactory radiographic appearance of the hip. The remaining seven patients had a satisfactory clinical outcome. However, an improved acetabular bone structure, as judged by radiographic evidence of incorporation of the bone grafts, was maintained in only four patients. In our experience, acetabular reconstruction with morseled bone grafts and a bipolar prosthesis was associated with a high rate of failure, and we do not recommend that it be performed routinely. It should be considered only as a salvage procedure in elderly or infirm patients, as a possible alternative to more extensive procedures.

Altered humoral immunoregulation during human pregnancy

The in vitro production of immunoglobulins in response to stimulation with pokeweed mitogen (PWM) and fixed/killed Staphylococcus aureus Cowan 1 (SAC) was measured in conjunction with in vivo assays of plasma immunoglobulin levels to examine the quality and quantity of humoral immunity during human pregnancy and at parturition. Following stimulation with PWM, there is a significant enhancement of in vitro immunoglobulin-G (IgG) production during pregnancy. Following stimulation with PWM and SAC, there was a significant reduction in in vitro immunoglobulin-M (IgM) production immediately following parturition. There was a significant decrease in the plasma levels of IgG during pregnancy, although no change in the plasma levels of IgM were observed. The decrease in plasma immunoglobulin levels during pregnancy cannot be explained as the result of hemodilution and transplacental transfer. Altered humoral immunoregulation is the most likely means whereby an increase in immunoglobulin production during human pregnancy could occur. The possible effects of this on the outcome of pregnancy are discussed.

Vaginal cones for the treatment of genuine stress incontinence

The value of vaginal cones for genuine stress incontinence was assessed in 34 women with this condition. Subjective and objective assessments were made before and after 6 weeks of treatment using urinary diaries, perineometry, 'home' pad test and cone weights with and without voluntary pelvic floor contraction. There was a subjective improvement in 23 of the 34 women (68%) after 6 weeks of cone use with 16 (47%) deciding that no additional treatment other than cone therapy was required at this time. Statistical analyses showed that there were significant improvements in the objective indices. There were no side-effects observed with cone use. When followed up 12-24 (mean 15.8) months from the start of the study, 14 women (41%) were still improved with either cone or pelvic floor exercises. Vaginal cones would seem to be a simple and practical means of improving both pelvic floor strength and genuine stress incontinence.

Morphological organization of thalamocortical relay cells in the dorsal lateral geniculate nucleus of the North American opossum

The morphology of relay cells in the dorsal lateral geniculate nucleus of the North American opossum was studied by using both Golgi-Cox material and cells stained from retrograde transport of horseradish peroxidase. In general, soma sizes were largest in the part of the nucleus representing the central retina and decreased from the middle third of the nucleus to the anterior to posterior poles. Relay cells labeled with horseradish peroxidase were found to constitute approximately 90% of the dorsal lateral geniculate nucleus cells and have larger soma diameters than most unlabeled cells. From morphometric analysis of several structural characteristics, three classes of relay cells were identified in both Golgi-Cox and horseradish peroxidase material. Type 1 cells, the predominant class, exhibited radially arranged primary dendritic fields, symmetrically organized relative to projection lines. Type 2 cells had relatively few primary dendrites, and complex dendritic fields that were oriented parallel to projection lines. Least numerous were Type 3 cells, which were characterized by relatively sparse dendritic fields oriented perpendicular to projection lines. An additional class of neuron, Type 4 cells, with small somata and sparse dendritic branching, was found only in Golgi-Cox material. Cells with Type 4 dendritic morphology were not found with retrograde horseradish peroxidase labeling and may represent interneurons. The classification of morphologically characterized cells in the opossum dorsal lateral geniculate nucleus was evaluated quantitatively with multivariate discriminant analysis. The classes are compared to physiologically identified Y-, X-, and W-like relay cells in the opossum and to relay cell classes in other species.

Axillary artery occlusion as a presenting feature of Crohn's disease

A 20 year old Caucasian woman with Crohn's disease is described in whom axillary artery occlusion due to arteritis dominated the clinical picture. This case demonstrates that isolated large vessel arteritis can be an unusual feature of Crohn's disease. Crohn's disease should be considered in any patient presenting with a large vessel arteritis.

Evaluation of the home pad test for quantifying incontinence

The home pad test to quantify urinary incontinence is described. Patients conduct the test in their homes and bring the pad, in a self-sealing plastic bag, for weighing at their next clinic visit. The validity of the procedure was assessed by measuring evaporation loss from the pads and comparing the home with the standard hospital test. Evaporation loss was shown to be acceptable if the test was carried out within 72 h of weighing. There were no significant differences between home and hospital tests and 95% of home results were within 32% below to 16% above hospital results. This was at least as consistent as the "gold standard" hospital test as 95% of the hospital results were within 28% below to 44% above repeated test results. The principal advantages in performing the pad test at home are simplicity, cost effectiveness and the relaxed environment, which reproduces more accurately the conditions leading to incontinence when compared with the relatively unfamiliar hospital setting.

Complications after total hip replacement. The contralateral limb

Six patients who had a total hip replacement, as well as a trochanteric osteotomy, while they were in the lateral decubitus position had complications involving the contralateral side. The complications included transient paresthesias, massive swelling of the thigh with myonecrosis, acute renal failure secondary to myoglobinuria, and arterial insufficiency that resulted in a below-the-knee amputation. In order to elucidate the causes of the complications, the external pressure of the contralateral femoral triangle and the blood flow to the contralateral foot were monitored intraoperatively in seventeen patients. The results supported the postulate that pressure at the groin is increased intraoperatively and that this can cause vascular compromise. Other proposed causes of the complications were pre-existing vascular disease, obesity, the lateral decubitus position of the patient on the operating table, and the use of hypotensive anesthesia. We found several techniques that may minimize complications in the contralateral limb during operations on the hip.

Epithelial polarity following ischemia: a requirement for normal cell function

Ischemic injury results in proximal tubule (PT) dysfunction and loss of surface membrane (SM) polarity. Since epithelial vectorial transport requires SM polarity, we set out to determine if correction of renal cortical PT dysfunction following ischemia was dependent on the reestablishment of SM polarity. Acute renal failure was induced using a bilateral 50-min pedicle clamp. Serum creatinine and fractional sodium excretion were maximal on day 1, remained elevated on day 3, and returned toward base line by day 8. PT cellular ultrastructure was normal by day 3. Despite rapid morphological recovery, ischemia resulted in a prolonged defect in glucose reabsorption. The delayed recovery of normal glucose handling closely paralleled the slow normalization of apical membrane lipid polarity. Na+-K+-ATPase polarity was also lost secondary to ischemia as demonstrated cytochemically and biochemically by the redistribution of Na+-K+-ATPase to the apical membrane. The time required to reestablish normal Na+-K+-ATPase polarity (8 days) paralleled the recovery of normal PT Na+ reabsorption (8 days), as assessed by fractional lithium clearances. This finding supports the hypothesis that apical Na+-K+-ATPase is in part responsible for reduced Na+ reabsorption following ischemic injury. In summary, these data suggest that functional recovery of PT glucose and Na+ reabsorption following a reversible ischemic insult requires not only morphological recovery, but also the reestablishment of surface membrane lipid and protein polarity.

Reduced cytotoxicity of the lysosomotropic detergent N-dodecylimidazole after differentiation of HL60 promyelocytes

The sensitivity of the human promyelocytic cell line HL60 to killing by the lysosomotropic detergent N-dodecyl imidazole (C12-Im) has been investigated in the exponential and stationary growth states and before and after differentiation induced by suitable effector molecules. Undifferentiated HL60 cells were more sensitive to killing by C12-Im in the rapid (exponential) phase of growth than in the stationary phase, in keeping with our observations on many other cell lines. Differentiation into granulocytes induced by dimethyl sulfoxide, or into macrophages induced by phorbol ester, resulted in a further dramatic decrease in sensitivity to C12-Im, as compared to undifferentiated HL60 cells in stationary phase. Viable cells remaining after treatment with C12-Im (60 micrograms/ml, 2 h) were: 0% for exponentially growing undifferentiated cells; 16% for stationary undifferentiated cells; 41% for differentiated granulocytes; and 29% for differentiated macrophages. Treatment with the cysteine cathepsin inhibitor L-trans-epoxysuccinylleucylamido(4-guanido)butane (E64) conferred resistance to C12-Im, showing that, in these cells, as previously demonstrated for Chinese hamster ovary fibroblasts, cysteine proteases were major cytotoxic agents involved in killing by C12-Im. Cell cathepsin B + L activity levels were dramatically reduced in those cells differentiated into granulocytes (11.2 units/mg of protein) and into macrophages (9.8 units/mg of protein) as compared with undifferentiated HL60 promyelocytes in stationary phase (30.4 units/mg of protein), correlating well with reduced sensitivity to C12-Im in the differentiated cells.

Characterization of ischemia-induced loss of epithelial polarity

Total renal ischemia for various time intervals (0-50 min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6 +/- 0.6 vs. 2.9 +/- 1.2, P less than 0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-to-phospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.

The prevalence of female urinary incontinence and reasons for not seeking treatment

The prevalence of urinary incontinence in women aged 18 years and over was investigated by carrying out a telephone interview of 851 women randomly selected from the Dunedin electoral register. Two hundred and sixty seven (31%) of the women interviewed had some degree of incontinence in the preceding 12 months and 142 (17%) had had regular incontinence (two or more episodes of leakage per month). Daily incontinence occurred in approximately 5% of the women sampled with 2.3% being incontinent more than once per day or being continually incontinent. Only one third of those with regular incontinence had sought medical help for their problem. The commonest reasons for this were that either the incontinence was not seen as abnormal (81%) or there was a low expectation of benefit from treatment (10%). Thus there needs to be improved awareness that incontinence is treatable and that medical and surgical treatment options are available.

Development of the optic nerve of the opossum (Didelphis virginiana)

The development of the optic nerve of a marsupial, the North American opossum, was examined in 24 animals from postnatal days 5 to 78 (P5-P78): gestation is 13 days. The estimated number of axons increased from 24,000 at P5, to 267,000 at P27, approximately 2.7 times the mean number in the adult. Following P27, axon numbers decreased rapidly to 140,000 at P40, then decreased more slowly, attaining adult values between P50 and P59. Thus, the opossum is similar to placental mammals examined in evidencing an overproduction and later attenuation to adult values in the number of axons in the optic nerve during development. Monocular enucleation of 3 animals at P17, 10 days before peak axon counts, resulted in a mean population increase of 24,000 (range 19,000-30,000) above the normal adult mean. Additionally, a 4th animal monocularly enucleated on P7, 3 days prior to the arrival of migrating fibers to central target sites, had a similar value of 26,500 supernumerary axons. Our findings in the opposum, when coupled with previous reports in other mammals, suggest that binocular interactions during development account only for optic nerve axon loss approximately equal in magnitude to the ipsilateral projection from one eye.