Erratum: Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande [Phys. Rev. Lett. 130, 031802 (2023)]

This corrects the article DOI: 10.1103/PhysRevLett.130.031802.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande

We report a search for cosmic-ray boosted dark matter with protons using the 0.37  megaton×years data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross section between 10^{-33}cm^{2} and 10^{-27}cm^{2} for dark matter mass from 1  MeV/c^{2} to 300  MeV/c^{2}.

Biocompatibility and degradation of gold-covered magneto-elastic biosensors exposed to cell culture

Magneto-elastic materials (ME) have important advantages when applied as biosensors due to the possibility of wireless monitoring. Commercial Metglas 2826MB3™ (FeNiMoB) is widely used, however sensor stabilization is an important factor for biosensor performance. This study compared the effects of biocompatibility and degradation of the Metglas 2826MB3™ alloy, covered or not with a gold layer, when in contact with cell culture medium. Strips of amorphous Metglas 2826MB3™ were cut and coated with thin layers of Cr and Au, as verified by Rutherford Backscattering Spectroscopy (RBS). Using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), the presence of metals in the culture medium was quantitatively determined for up to seven days after alloy exposure. Biocompatibility of fibroblast Chinese Hamster Ovary (CHO) cultures was tested and cytotoxicity parameters were investigated by indirect means of reduction of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) at 1, 2 and 7 days. Cell death was further evaluated through in situ analysis using Acridine Orange/Ethidium Bromide (AO/EB) staining and images were processed with ImageJ software. Ions from Metglas(®) 2826MB3™ induced a degradation process in living organisms. The cytotoxicity assay showed a decrease in the percentage of live cells compared to control for the ME strip not coated with gold. AO/EB in situ staining revealed that most of the cells grown on top of the gold-covered sensor presented a normal morphology (85.46%). Covering ME sensors with a gold coating improved their effectiveness by generating protection of the transducer by reducing the release of ions and promoting a significant cell survival.

Newborns and low to moderate prenatal environmental lead exposure: might fathers be the key?

This study is part of the BioMadrid Project, a bio-monitoring study designed to assess pollutants in the environment surrounding children born in the Madrid region. Our aim in this report is to evaluate the association between prenatal lead exposure and fetal development using three biological samples (maternal and paternal blood lead at around 34 weeks of gestation as well as cord blood lead levels), three biomarkers of effect in cord blood peripheral lymphocytes (micronucleus in binucleated cells, nucleoplasmic bridges, and nuclear buds), and different anthropometrical characteristics at birth. Maternal and cord blood lead were not associated with newborn measurements or genotoxicity biomarkers. In contrast, increases in father blood lead were coupled with lower weight (mean difference (MD), -110.8 g; 95% confidence intervals (95%CI), -235.6 to 6.00; p < 0.10) and shorter abdominal (MD, -0.81 cm; 95%CI, -1.64 to 0.00; p < 0.05) and cephalic (MD, -0.32 cm; 95%CI, -0.65 to 0.00; p < 0.05) circumferences at birth as well as with the presence of nucleoplasmic bridges (odds ratio, 1.03; 95%CI, 1.00 to 1.06; p < 0.05) and nuclear buds (odds ratio, 1.02; 95%CI, 0.99 to 1.04; p < 0.10). These associations were mainly confined to female babies, in whom paternal lead was also inversely associated with length. Our results support the hypothesis that paternal lead exposure may be affecting the development of newborns.

Lead, mercury and cadmium in umbilical cord blood and its association with parental epidemiological variables and birth factors

Background

In Spain, few studies have evaluated prenatal exposure to heavy metals. The objective of this study was to describe lead, mercury and cadmium concentrations in blood from a sample of newborn–mother-father trios, as well as to investigate the association between metals in cord blood and parental variables. We also explored the relationship between cord blood metal concentrations and child characteristics at birth.

Methods

Metal correlations among family members were assessed using Spearman Rank Correlation Coefficient. Linear regression was used to explore the association between parental variables and log-transformed cord blood lead and cord blood mercury concentrations. In the case of cadmium, tobit regression was used due to the existence of samples below the detection limit. The association between cord blood metal concentrations and child characteristics at birth was evaluated using linear regression.

Results

Geometric means for lead, mercury and cadmium were 14.09 μg/L, 6.72 μg/L and 0.27 μg/L in newborns; 19.80 μg/L, 3.90 μg/L and 0.53 μg/L in pregnant women; and 33.00 μg/L, 5.38 μg/L and 0.49 μg/L in men. Positive correlations were found between metal concentrations among members of the trio. Lead and cadmium concentrations were 15% and 22% higher in newborns from mothers who smoked during pregnancy, while mercury concentrations were 25% higher in newborns from mothers with greater fish intake. Cord-blood lead levels showed seasonal periodicity, with lower concentrations observed in winter. Cord blood cadmium concentrations over 0.29 μg/L were associated with lower 1-minute and 5-minute Apgar scores.

Conclusions

These results reinforce the need to establish biomonitoring programs in Spain, and provide support for tobacco smoke and fish consumption as important preventable sources of heavy metal exposure in newborns. Additionally, our findings support the hypothesis that cadmium exposure might be deleterious to fetal development.

Mercury, lead and cadmium in human milk in relation to diet, lifestyle habits and sociodemographic variables in Madrid (Spain)

BACKGROUND

Although breastfeeding is the ideal way of nurturing infants, it can be a source of exposure to toxicants. This study reports the concentration of Hg, Pb and Cd in breast milk from a sample of women drawn from the general population of the Madrid Region, and explores the association between metal levels and socio-demographic factors, lifestyle habits, diet and environmental exposures, including tobacco smoke, exposure at home and occupational exposures.

METHODS

Breast milk was obtained from 100 women (20 mL) at around the third week postpartum. Pb, Cd and Hg levels were determined using Atomic Absorption Spectrometry. Metal levels were log-transformed due to non-normal distribution. Their association with the variables collected by questionnaire was assessed using linear regression models. Separate models were fitted for Hg, Pb and Cd, using univariate linear regression in a first step. Secondly, multivariate linear regression models were adjusted introducing potential confounders specific for each metal. Finally, a test for trend was performed in order to evaluate possible dose-response relationships between metal levels and changes in variables categories.

RESULTS

Geometric mean Hg, Pb and Cd content in milk were 0.53 μg L(-1), 15.56 μg L(-1), and 1.31 μg L(-1), respectively. Decreases in Hg levels in older women and in those with a previous history of pregnancies and lactations suggested clearance of this metal over lifetime, though differences were not statistically significant, probably due to limited sample size. Lead concentrations increased with greater exposure to motor vehicle traffic and higher potato consumption. Increased Cd levels were associated with type of lactation and tended to increase with tobacco smoking.

CONCLUSIONS

Surveillance for the presence of heavy metals in human milk is needed. Smoking and dietary habits are the main factors linked to heavy metal levels in breast milk. Our results reinforce the need to strengthen national food safety programs and to further promote avoidance of unhealthy behaviors such as smoking during pregnancy.

Cytogenetic status in newborns and their parents in Madrid: the BioMadrid study

Monitoring cytogenetic damage is frequently used to assess population exposure to environmental mutagens. The cytokinesis-block micronucleus assay is one of the most widely used methods employed in these studies. In the present study we used this assay to assess the baseline frequency of micronuclei in a healthy population of father-pregnant woman-newborn trios drawn from two Madrid areas. We also investigated the association between micronucleus frequency and specific socioeconomic, environmental, and demographic factors collected by questionnaire. Mercury, arsenic, lead, and cadmium blood levels were measured by atomic absorption spectrometry. The association between micronucleated cell frequency and the variables collected by questionnaire, as well as, the risk associated with the presence of elevated levels of metals in blood, was estimated using Poisson models, taking the number of micronucleated cells in 1,000 binucleated cells (MNBCs) as the dependent variable. Separate analyses were conducted for the 110 newborns, 136 pregnant women, and 134 fathers in whom micronuclei could be assessed. The mean number of micronucleated cells per 1,000 binucleated cells was 3.9, 6.5, and 6.1 respectively. Our results show a statistically significant correlation in MNBC frequency between fathers and mothers, and between parents and newborns. Elevated blood mercury levels in fathers were associated with significantly higher MNBC frequency, compared with fathers who had normal mercury levels (RR:1.21; 95%CI:1.02-1.43). This last result suggests the need to implement greater control over populations which, by reason of their occupation or life style, are among those most exposed to this metal.

High density flux of Co nanoparticles produced by a simple gas aggregation apparatus

Gas aggregation is a well known method used to produce clusters of different materials with good size control, reduced dispersion, and precise stoichiometry. The cost of these systems is relatively high and they are generally dedicated apparatuses. Furthermore, the usual sample production speed of these systems is not as fast as physical vapor deposition devices posing a problem when thick samples are needed. In this paper we describe the development of a multipurpose gas aggregation system constructed as an adaptation to a magnetron sputtering system. The cost of this adaptation is negligible and its installation and operation are both remarkably simple. The gas flow for flux in the range of 60-130 SCCM (SCCM denotes cubic centimeter per minute at STP) is able to completely collimate all the sputtered material, producing spherical nanoparticles. Co nanoparticles were produced and characterized using electron microscopy techniques and Rutherford back-scattering analysis. The size of the particles is around 10 nm with around 75 nm/min of deposition rate at the center of a Gaussian profile nanoparticle beam.

Transitions in the orientational order of liquid crystals induced by periodic patterned substrates

The orientational order of liquid crystals (LCs) induced by periodic patterned substrates has been investigated with cells coated by azopolymer films that could be photoaligned in a controlled way. Two regimes were observed depending on the period of the patterns: (i) above 3.0 microm the LC follows the direction imposed by the patterned substrate since the energy stored in the surface potential minimizes the elastic energy of the LC medium. (ii) For periods smaller than 1.0 microm a homogeneous in-plane state was induced and the LC did not follow the orientation imposed by the surface. This in-plane transition could be explained qualitatively by a theoretical model based on the competition between the Frank-Oseen elastic energy and the phenomenological surface potential. The results also suggest an out-of-plane transition for the LC director as the period was reduced. These results agree with data in the literature for patterned substrates with completely distinct architectures. This indicates that for a particular LC sample the overall behavior depends basically on the texture period instead of the texture architecture. The textures were characterized with a scanning near-field optical microscope (SNOM), which allowed simultaneous morphological and optical images in the submicrometer range.

Physico-chemical properties of MTA and a novel experimental cement

AIM

To evaluate the release of calcium ions, pH and conductivity of a new experimental dental cement (EC) and to compare them with those of mineral trioxide aggregate (MTA-Angelus).

METHODOLOGY

Five samples of each cement were prepared using plastic tubes 1 mm in diameter and 10 mm long. Each sample was sealed in a test tube containing 10 mL deionized water which was analysed after 24, 48, 72, 96, 192, 240 and 360 h for pH, electrical conductivity and calcium release. The concentration of calcium ions was obtained through atomic absorption spectroscopy technique. The data were analysed statistically using the analysis of variance (anova) and the Student's test (t-test).

RESULTS

The pH of the storage solutions was not affected by the material and the interaction of material with time (P > 0.05). However, the time of immersion was significant (P < 0.01) for both materials. For the electric conductivity and calcium release, the interaction of material with time was statistically significant (P < 0.01), indicating that EC and MTA-Angelus did not behave in a similar manner.

CONCLUSIONS

The experimental cement released calcium and increased the pH of the storage solutions in a similar manner to MTA-Angelus. However, EC showed significantly higher calcium release than commercial MTA-Angelus after 24 h.

Magnetic characterization of microscopic particles by MO-SNOM

This paper reports on the development of a magneto-optical scanning near-field optical microscope and the experimental near-field study of the domain structure for a model magnetic particle of 16 x 16 micro m(2) of a Co(70.4)Fe(4.6)Si(15)B(10) amorphous thin film, deposited on a silicon substrate. We present the topographic, optical and magneto-optical differential susceptibility (MODS) images of the particle. Imaging by using the local MODS reveals the domain structure. These images are also used for positioning the tip in order to acquire local hysteresis loops, with submicrometre spatial resolution.

Conus peptides targeted to specific nicotinic acetylcholine receptor subtypes

The venoms of predatory cone snails represent a rich combinatorial-like library of evolutionarily selected, neuropharmacologically active peptides. A major fraction of the venom components are conotoxins--small, disulfide-rich peptides that potently and specifically target components of the neuromuscular system, particularly ligand- and voltage-gated ion channels. This review focuses on Conus peptides, which act at nicotinic acetylcholine receptors. These nicotinic antagonist peptides from Conus are broadly divided into two groups: those that act at the neuromuscular junction and those that act at subtypes of neuronal nicotinic acetylcholine receptors. The latter include peptides specific for the alpha 7, alpha 3 beta 2, and alpha 3 beta 4 nicotinic receptor subtypes. The degree of specificity exhibited by these peptides is remarkable, particularly given their relatively small size. As a group the nicotinic acetylcholine receptor-targeted Conus peptides represent an increasingly well-defined set of tools for probing the structure, function, and physiological role of nicotinic acetylcholine receptors.

Fibrodysplasia ossificans progressiva: case report

Fibrodysplasia ossificans progressiva is a rare genetic disease characterized by widespread soft tissue ossification and congenital stigmata of the extremities. We report on a male child followed for ten years since the age of 3 years and 9 months, when the diagnosis was made. He was born with bilateral hypoplasic hallux valgus and ventricular septal defect, corrected by trans-sternal approach when 32 months old. Restriction of neck mobility followed and foci of ectopic ossification appeared. Four crises of disease exacerbation were treated with oral prednisone and/or other antiinflammatory drugs. Sodium etidronate 5 to 10 mg/kg/day was prescribed intermittently during about six years but was discontinued due to osteopenia. The disease course has been relentless, with severe movement restriction including the chest wall. A review showed few similar case reports in the Brazilian literature. We revisit the criteria for diagnosis and the essentials of management and treatment.

Does mRNA translation starting from an alternative initiation site contribute to the pathology of Huntington's disease?

Huntington's disease is associated with an expanded and unstable trinucleotide repeat (CAG)(n). Various possibilities have been suggested to explain the significance of poly-(CAG) length in HD, including changes in the structure of the product (huntingtin) which result in the protein acquiring deleterious properties. We have looked at the nucleotide sequence coding for huntingtin and find that another possibility may exist for the correlation between the occurrence of HD and poly-CAG length. We have noted an alternative reading frame that includes the trinucleotide repeat, now read as (GCA)(n). Upon close examination of this alternative gene product, we observe features that suggest it can likewise have deleterious properties.

Generation and characterization of a single gene-encoded single-chain-tetravalent antitumor antibody

Monoclonal antibody (mAb) CC49, a murine IgG1, reacts with the tumor-associated glycoprotein-72 expressed on a variety of carcinomas. In clinical trials, radiolabeled CC49 has shown excellent tumor localization to a variety of carcinomas. To minimize the immunogenicity of CC49 mAb in patients, a humanized CC49 (HuCC49) was generated by complementarity-determining region (CDR) grafting. The relative affinity of HuCC49 was 2-3-fold less than that of the murine mAb. With the aim of improving tumor targeting, attempts have been made to enhance the avidity of the HuCC49 mAb. Previous research has yielded a single gene-encoded immunoglobulin, SCIgcCC49deltaCH1, which is a dimer of a single chain consisting of CC49 single-chain Fv linked to the NH2 terminus of the human gamma1 Fc through the hinge region. This molecule is comparable to the mouse-human chimeric CC49 in terms of in vitro antigen binding properties, cytolytic activity, and rate of plasma clearance in athymic mice bearing human tumor xenografts. Recently, a single gene encoding a single-chain immunoglobulin consisting of a HuCC49 diabody attached to human gamma1 Fc via the hinge region was constructed. The diabody, a bivalent antigen-binding structure, is made up of variable heavy (V(H))/variable light (V(L)) domains and V(L)/V(H) domains. In each of the variable domain pairs, the V(H) and V(L) domains are linked through a short linker peptide. Meanwhile, the two pairs are linked via a 30-residue Gly-Ser linker peptide to yield two antigen-binding sites by lateral and noncovalent association of the V(L) of one pair with the V(H) of the other. Transfectomas expressing the single-gene immunoglobulin secrete a homodimer of about Mr 160,000 that reacts to tumor-associated glycoprotein-72. This tetravalent humanized antitumor immunoglobulin molecule may potentially be an efficacious therapeutic and diagnostic reagent against a wide range of human carcinomas.

Speciation of cone snails and interspecific hyperdivergence of their venom peptides. Potential evolutionary significance of introns

All 500 species of cone snails (Conus) are venomous predators. From a biochemical/genetic perspective, differences among Conus species may be based on the 50-200 different peptides in the venom of each species. Venom is used for prey capture as well as for interactions with predators and competitors. The venom of every species has its own distinct complement of peptides. Some of the interspecific divergence observed in venom peptides can be explained by differential expression of venom peptide superfamilies in different species and of peptide superfamily branching in various Conus lineages into pharmacologic groups with different targeting specificity. However, the striking interspecific divergence of peptide sequences is the dominant factor in the differences observed between venoms. The small venom peptides (typically 10-35 amino acids in length) are processed from larger prepropeptide precursors (ca. 100 amino acids). If interspecific comparisons are made between homologous prepropeptides, the three different regions of a Conus peptide precursor (signal sequence, pro-region, mature peptide) are found to have diverged at remarkably different rates. Analysis of synonymous and nonsynonymous substitution rates for the different segments of a prepropeptide suggests that mutation frequency varies by over an order of magnitude across the segments, with the mature toxin region undergoing the highest rate. The three sections of the prepropeptide which exhibit apparently different mutation rates are separated by introns. This striking segment-specific rate of divergence of Conus prepropeptides suggests a role for introns in evolution: exons separated by introns have the potential to evolve very different mutation rates. Plausible mechanisms that could underlie differing mutational frequency in the different exons of a gene are discussed.

An O-glycosylated neuroexcitatory conus peptide

We purified and characterized a novel peptide from the venom of the fish-hunting cone snail Conus striatus that inhibits voltage-gated K+ channels. The peptide, kappaA-conotoxin SIVA, causes characteristic spastic paralytic symptoms when injected into fish, and in frog nerve-muscle preparations exposed to the toxin, repetitive action potentials are seen in response to a single stimulus applied to the motor nerve. Other electrophysiological tests on diverse preparations provide evidence that is consistent with the peptide blocking K+ channels. The peptide has three disulfide bonds; the locations of Cys residues indicate that the spastic peptide may be the first and defining member of a new family of Conus peptides, the kappaA-conotoxins, which are structurally related to, but pharmacologically distinct from, the alphaA-conotoxins. This 30 AA tricyclic toxin has several characteristics not previously observed in Conus peptides. In addition to the distinctive biological and physiological activity, a novel biochemical feature is the unusually long linear N-terminal tail (11 residues) which contains one O-glycosylated serine at position 7. This is the first evidence for O-glycosylation as a posttranslational modification in a biologically active Conus peptide.

Development of more efficacious antibodies for medical therapy and diagnosis

Two procedures for improving the efficacy of medically important antibodies are described. The first procedure is designed to reduce the immunogenicity of nonhuman antibodies to the barest minimum--the "humanization" is accomplished by transplanting only the specificity-determining residues of the nonhuman antibody onto a human antibody template. The second procedure is designed to permit the easy production of multispecific/multivalent antibodies via heterodimer formation of electrostatically complementary Fc regions.

Bilateral pseudocyst of the auricle in an infant girl

A 6-week-old girl developed bilateral auricular swelling in the absence of trauma. Clinical and histologic findings were consistent with pseudocyst of the auricle. This case is unusual given the age and sex of the patient and the bilateral presentation of the pseudocysts.

Frequency-domain interferometer for measuring the phase and amplitude of a femtosecond pulse probing a laser-produced plasma

A frequency-domain interferometer for probing the variations of the dielectric constant of a plasma with sub-100- fs temporal resolution and lambda/2000 phase resolution is described. Imaging the plasma on the entrance slit of a spectrograph provides spatial resolution along a diameter of the focal spot. The technique is used to map out the expansion of the critical density surface of a femtosecond laser-produced plasma with subnanometer spatial resolution along the laser axis.

Heterodimeric structure of the spider toxin omega-agatoxin IA revealed by precursor analysis and mass spectrometry

We report the first molecular characterization of a precursor sequence for a small, Ca2+ channel blocking, peptide spider toxin, omega-agatoxin IA. By integrating information generated from a molecular genetic approach using agatoxin cDNAs with data provided from mass spectrometry of the mature toxin, we were able to deduce the likely mechanisms by which the toxin precursor peptide is processed to its mature heterodimeric form. A particularly interesting feature of the prepropeptide is the occurrence of two glutamate-rich sequences interposed between the signal sequences, the major peptide toxin, and the minor toxin peptide. Excision of the more distal glutamate-rich region appears to be signaled by flanking arginine residues but likely occurs only after a disulfide linkage has formed between the major and minor chains of the mature toxin. Our molecular genetic approach toward characterizing this toxin will allow us to quickly generate a series of spider sequences from which mature toxin structures can be deduced and eventually expressed. Additionally, this approach will provide insights into the evolutionary divergence observed among spider peptide toxins.

Correction of esophageal atresia with distal tracheoesophageal fistula

Correction of the full spectrum of esophageal atresia with tracheoesophageal fistula (TEF) remains controversial. Circular myotomy and other lengthening procedures have shown promise to reduce tension when a relatively wide gap exists between esophageal segments; nevertheless a relatively high complication rate persists. We believe anastomotic tension is commonly found with repair of this anomaly. Therefore, the construction of the anastomosis will be a primary determinant of success. Twenty-four infants with TEF were admitted, 12 (50%) weighing 2.5 kg, nine (37%) 1.8 to 2.5 kg, and three (13%) 1.8 kg. All underwent gastrostomy and end-to-end single-layer anastomosis. Gaps of up to 4.5 cm were encountered, and in one case a cervical incision was necessary for mobilization of the upper pouch. For eight patients (33%) the gap was at least 2.5 cm and significant anastomotic tension was generated. For the series, there were no anastomotic leaks (all confirmed by barium swallow), reoperations, or surgical complications (there were two late, unrelated deaths). Prophylactic dilation was routinely performed 6 weeks and 3 months postoperatively. Subsequently, seven of the 24 (29%) required additional (one to five) dilatations but are now asymptomatic at least 2 years later. Follow-up for the entire series is 5 months to 5 years. Three infants (13%) required fundoplication for reflux without stricture and two infants (8%) an aortopexy. For successful esophageal anastomosis we consider the following technical points important: (1) no-touch technique to minimize tissue damage, (2) generous (5 to 7 mm) full-thickness suture depth, (3) fine (6/0) monofilament suture to reduce tissue reactivity, and (4) in cases of significant tension, the sutures are preplaced and used to provide traction to eliminate tension during tying. Tension is often unavoidable in TEF, yet a carefully constructed anastomosis will withstand this stress. This approach provides results at least as satisfactory as the reported experience with a variety of techniques.

Orthostatic hypotension: a commonly unrecognized cause of symptoms in mitral valve prolapse

To test the hypothesis that orthostatic hypotension could represent an alternative mechanism contributing to the symptoms of mitral valve prolapse, the systolic and diastolic arterial blood pressures were measured in the supine and standing positions in 86 patients with the diagnosis confirmed by echocardiography. Orthostatic hypotension was demonstrated in 12 patients. Ten of them presented with a history of recurrent lightheadedness, dizziness or syncope and constitute 59 percent of the total number of patients with such symptoms in this series. Although nine of these 10 patients reported transient lightheadedness or dizziness during periods of ambulatory electrocardiographic recording, in only one were the symptoms chronologically related to cardiac arrhythmias. On the other hand, eight of them described lightheadedness and two experienced near-syncope during the postural test in association with the orthostatic drop in blood pressure. Improvement in symptoms and correction of the orthostatic hypotension were demonstrated in seven patients after beta-adrenergic blockade with propranolol. Before therapy, the mean systolic blood pressure dropped from 114 +/- 3 mm Hg in the supine position to 78 +/- 1 mm Hg upon standing (p less than 0.001). In repeated postural tests performed after four weeks of treatment, the systolic blood pressure changed from 120 +/- 3 mm Hg supine to 115 +/- 1 mm Hg upon standing (p greater than 0.01). We conclude that orthostatic hypotension is a commonly unrecognized mechanism responsible for some of the symptoms of mitral valve prolapse, particularly in patients affected by recurrent lightheadedness, dizziness or syncope.

Echocardiographic characterization of the reversible cardiomyopathy of hypothyroidism

Nineteen patients with untreated hypothyroidism were evaluated by M-mode echocardiography. Asymmetric septal hypertrophy (ASH), defined as a ratio of interventricular septal thickness to left ventricular posterior wall thickness (IVS/LVPW) equal to or greater than 1.3, was identified in 17 cases. Additional abnormalities recognized by echocardiography included reduced amplitude of systolic septal excursion (SSex) [13 patients], reduced per cent of systolic septal thickening (%SST)[19 patients], reduced left ventricular outflow tract dimension (LVOT)[five patients] and systolic anterior motion of the mitral valve (SAM)[five patients]. These findings are similar to some of the echocardiographic features of idiopathic hypertrophic subaortic stenosis (IHSS). In 10 patients who returned to euthyroid state with L-thyroxine therapy, these abnormalities resolved. We conclude that long-standing hypothyroidism leads to a reversible cardiomyopathy, manifested by asymmetric septal hypertrophy with or without other echocardiographic features of a hypertrophic obstructive cardiomyopathy. This previously unrecognized features of hypothyroidism has important diagnostic and therapeutic implications.

Effects of coronary artery bypass surgery on hemodynamic parameters and derived indices of myocardial function

Pre- and postoperative hemodynamic indices were compared in 116 patients subjected to aorto-coronary bypass after an average interval of 128 days. The patients were separated into three different groups according to graft status: Group 1 (n = 77), all grafts patent; Group 2 (n = 27), one occluded graft out of two or three implanted; Group 3 (n = 12), all grafts occluded. There were no significant major changes of values so obtained in the three groups. Those subjects with initially depressed cardiac indices or elevated left ventricular end-diastolic pressures manifested a significant trend toward improvement when at least one bypass graft was patent. A reduction of cardiac index was noted in patients with occluded left anterior descending coronary grafts only in association with closure of other grafts. Deterioration of cardiac index or left ventricular end-diastolic pressure into the abnormal range was unusual in the study group, even when all grafts were occluded. It is concluded that data relating to the influence of aorto-coronary bypass on standard indices of left ventricular function can be properly interpreted only when certain subsets of patients are studied.