Increased COVID-19 mortality among immigrants compared with US-born individuals: a cross-sectional analysis of 2020 mortality data

OBJECTIVE

Multiple studies have shown that racially minoritized groups had disproportionate COVID-19 mortality relative to non-Hispanic White individuals. However, there is little known regarding mortality by immigrant status nationally in the United States, despite being another vulnerable population.

STUDY DESIGN

This was an observational cross-sectional study using mortality vital statistics system data to calculate proportionate mortality ratios (PMRs) and mortality rates due to COVID-19 as the underlying cause.

METHODS

Rates were compared by decedents' identified race, ethnicity (Hispanic vs non-Hispanic), and immigrant (immigrants vs US born) status. Asian race was further disaggregated into "Asian Indian," "Chinese," "Filipino," "Japanese," "Korean," and "Vietnamese."

RESULTS

Of the over 3.4 million people who died in 2020, 10.4% of all deaths were attributed to COVID-19 as the underlying cause (n = 351,530). More than double (18.9%, n = 81,815) the percentage of immigrants who died of COVID-19 compared with US-born decedents (9.1%, n = 269,715). PMRs due to COVID-19 were higher among immigrants compared with US-born individuals for non-Hispanic White, non-Hispanic Black, Hispanic, and most disaggregated Asian groups. Among disaggregated Asian immigrants, age- and sex-adjusted PMR due to COVID-19 ranged from 1.58 times greater mortality among Filipino immigrants (95% confidence interval [CI]: 1.53, 1.64) to 0.77 times greater mortality among Japanese immigrants (95% CI: 0.68, 0.86). Age-adjusted mortality rates were also higher among immigrant individuals compared with US-born people.

CONCLUSIONS

Immigrant individuals experienced greater mortality due to COVID-19 compared with their US-born counterparts. As COVID-19 becomes more endemic, greater clinical and public health efforts are needed to reduce disparities in mortality among immigrants compared with their US-born counterparts.

Climate change and human health in Vietnam: a systematic review and additional analyses on current impacts, future risk, and adaptation

This study aims to investigate climate change's impact on health and adaptation in Vietnam through a systematic review and additional analyses of heat exposure, heat vulnerability, awareness and engagement, and projected health costs. Out of 127 reviewed studies, findings indicated the wider spread of infectious diseases, and increased mortality and hospitalisation risks associated with extreme heat, droughts, and floods. However, there are few studies addressing health cost, awareness, engagement, adaptation, and policy. Additional analyses showed rising heatwave exposure across Vietnam and global above-average vulnerability to heat. By 2050, climate change is projected to cost up to USD1-3B in healthcare costs, USD3-20B in premature deaths, and USD6-23B in work loss. Despite increased media focus on climate and health, a gap between public and government publications highlighted the need for more governmental engagement. Vietnam's climate policies have faced implementation challenges, including top-down approaches, lack of cooperation, low adaptive capacity, and limited resources.

Risk of transient vision loss after intravitreal aflibercept using vial-prepared vs. the novel prefilled syringe formulation

Purpose

To compare the risk of transient vision loss (TVL) probably attributable to a severe intraocular pressure spike after intravitreal aflibercept application using the novel prefilled syringe (PFS) vs. the established vial system (VS).

Methods

Datasets of the intravitreal injection service of the Ludwig Maximilians-University Munich and the Technical University Munich, Germany, were screened for documentation of TVL after intravitreal injection of aflibercept. The observation period included two full months prior to the introduction of the novel PFS and two months afterwards. TVL was defined as loss of perception of hand motion for a duration of >30 s.

Results

Over a period of four months, 1720 intravitreal injections of aflibercept were administered in 672 patients. There were 842 injections with the old VS, and 878 injections using the novel PFS. Using the VS, TVL was noted during two injections (0.24%) in two patients, as compared to 11 cases of TVL (1.25%) in 10 patients with the PFS (p = 0.015). Using the PFS, patients had a 5.3-fold risk of TVL as compared to the VS (OR: 5.33; 95% CI: 1.2-24.1; p = 0.0298).

Conclusion

There was a more than five-fold risk of TVL using the novel pre-filled aflibercept syringe as compared to the established vial system. During informed consent, this risk should be discussed.

Carbon Capture Membranes Based on Amorphous Polyether Nanofilms Enabled by Thickness Confinement and Interfacial Engineering

Thin-film composite membranes are a leading technology for post-combustion carbon capture, and the key challenge is to fabricate defect-free selective nanofilms as thin as possible (100 nm or below) with superior CO₂/N₂ separation performance. Herein, we developed high-performance membranes based on an unusual choice of semi-crystalline blends of amorphous poly(ethylene oxide) (aPEO) and 18-crown-6 (C6) using two nanoengineering strategies. First, the crystallinity of the nanofilms decreases with decreasing thickness and completely disappears at 500 nm or below because of the thickness confinement. Second, polydimethylsiloxane is chosen as the gutter layer between the porous support and selective layer, and its surface is modified with bio-adhesive polydopamine (<10 nm) with an affinity toward aPEO, enabling the formation of the thin, defect-free, amorphous aPEO/C6 layer. For example, a 110 nm film containing 40 mass % C6 in aPEO exhibits CO₂ permeability of 900 Barrer (much higher than a thick film with 420 Barrer), rendering a membrane with a CO₂ permeance of 2200 GPU and CO₂/N₂ selectivity of 27 at 35 °C, surpassing Robeson's upper bound. This work shows that engineering at the nanoscale plays an important role in designing high-performance membranes for practical separations.

Effect of multiple micronutrient supplementation on pregnancy and infant outcomes: a systematic review

Supplementation with multiple micronutrients (MM) during pregnancy may result in improved pregnancy and infant outcomes. We conducted meta-analyses of randomised controlled trials that evaluated the effects of prenatal supplementation with MM (defined as containing at least five micronutrients and typically included iron or iron and folic acid). The outcomes of interest were low birthweight (<2500 g), birthweight, small-for-gestational age (SGA), gestational age, preterm birth (<37 weeks' gestation), stillbirth and neonatal death, maternal morbidity and mortality. We identified eligible studies through PubMed and EMBASE database searches. Meta-analyses were performed by pooling results for outcomes that were reported from more than one trial and sub-analyses were conducted to evaluate the effect of timing of intervention and amount of iron. We included published results from 16 trials in this review. Compared with control supplementation that was usually iron plus folic acid in most studies, MM supplementation resulted in a significant reduction in the incidence of low birthweight [pooled risk ratio (RR) 0.86; 95% confidence interval (CI) 0.81, 0.91] and SGA (pooled RR 0.83 [95% CI 0.73, 0.95]) and an increase in mean birthweight (weighted mean difference (WMD) 52.6 g [95% CI 43.2 g, 62.0 g]). There was no significant difference in the overall risk of preterm birth, stillbirth, and maternal or neonatal mortality, but we found an increased risk of neonatal death for the MM group compared with iron-folate in the subgroup of five trials that began the intervention after the first trimester (RR 1.38 [95% CI 1.05, 1.81]). None of the studies evaluated maternal morbidity. Compared with iron plus folic acid supplementation alone, prenatal maternal supplementation with MM resulted in a reduction in the incidence of low birthweight and SGA but increased risk of neonatal death in the subgroup of studies that began the intervention after the first trimester.

Septic arthritis in a native joint due to Anaerococcus prevotii

A 37-year-old injecting drug user presented with signs and symptoms of septic arthritis. Staphylococcus aureus was grown from his blood cultures. Despite treatment with flucloxacillin and fusidic acid his condition continued to deteriorate. Echocardiography showed no signs of endocarditis. Culture of his knee aspirate grew Anaerococcus prevotii after 5 days of incubation. Metronidazole was added to his treatment regime. A collection of pus (800 ml) was drained from the right thigh and A prevotii was isolated. His condition improved gradually and he was subsequently transferred to a drug rehabilitation unit after completing his antibiotic course. The importance of anaerobic streptococci in septic arthritis, as a very rare cause, is highlighted.

NO inhibition of the magnocellular neuroendocrine system in rats is independent of cGMP signaling pathway

Our objective was to test the hypothesis that the cGMP signal-transduction mechanism mediates nitric oxide's (NO) modulation of oxytocin (OT) and vasopressin (VP) secretion from the hypothalamo-neurohypophysial system. Three studies were conducted in adult male Sprague-Dawley rats: (1a) Euhydrated rats received an intracerebroventricular (icv) infusion (1 microl/min for 30 min) of artificial cerebrospinal fluid (aCSF), vehicle (2.6% dimethyl sulfoxide [DMSO]) or 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) (0.05 microg/microl), an inhibitor of soluble guanylyl cyclase (sGC). ODQ did not affect basal levels of plasma VP or OT; (1b) Rats dehydrated for 24 h received aCSF or 8-Br-cGMP (icv), a membrane-permeable analog of cGMP, and plasma hormones were measured 2 min later. 8-Br-cGMP did not significantly change VP or OT levels; (2) Rats ingested water or 2% NaCl for 4 days, and NO synthase (NOS) and sGC activities were measured in posterior pituitaries, the anatomical site of hormone secretion. Salt loading enhanced (P < 0.001) production of [(14)C]citrulline, the coproduct of NO synthesis, without altering cGMP; (3) One SON was microdialyzed with [(14)C]arginine and NOS and sGC activities were quantified in microdialysates during intravenous (iv) infusion of isotonic or hypertonic saline in awake and anesthetized rats. In awake rats, [(14)C]citrulline recovery, but not cGMP, increased (P < 0.05) during intravenous infusion of both isotonic and hypertonic solutions, and after insertion of microdialysis probe itself. In anesthetized rats, however, where basal NOS activity is low, intravenous infusion of hypertonic, but not isotonic solution, increased [(14)C]citrulline recovery without affecting cGMP. Thus, in the forebrain, neither NO produced basally nor during osmotic stimulation depends on cGMP to modulate plasma vasopressin and oxytocin secretion.

Competency-based student self-assessment on a surgery rotation

BACKGROUND

Although self-assessment is an essential component of self-directed adult learning, few data exist regarding the ability of medical students to perform this important task. Therefore, the purpose of this study was to evaluate the ability of medical students to perform self-assessment during a third-year surgery clerkship.

METHODS

Sixty-eight (34 male, 34 female) third-year medical students assessed their progress at the midpoint of an 8-week surgery clerkship using an 11-item, competency-based evaluation. Students compared perceptions of their performance with a faculty member's assessment using the identical evaluation form.

RESULTS

Male students tended to overestimate their midclerkship performance compared with faculty formative and summative evaluations (3.31 +/- 0.03 vs 3.23 +/- 0.03 and 3.28 +/- 0.03) although this did not reach statistical significance. Female students significantly underestimated their midclerkship performance compared with faculty formative and summative evaluations (3.06 +/- 0.03 vs 3.40 +/- 0.03 and 3.45 +/- 0.03, P < 0.05 vs faculty evaluations). Preclerkship academic performance (first- and second-year grade point averages and NBME Part 1 scores) was not predictive of student self-assessment. Finally, women statistically outperformed men on the surgery clerkship (86.6% +/- 0.75 vs 83.2% +/- 1.20, P < 0.05 vs male students).

CONCLUSIONS

Female students tend to underestimate their midclerkship performance compared with male students on a surgery rotation. Despite lower self-assessment, female students actually outperform male students. Women may underreport their capabilities when compared with men as a result of gender differences in socialization. These gender differences in self-assessment may be important to recognize when faculty provide feedback to students.

Central interactions between angiotensin II and PGD(2) in the regulation of vasopressin and oxytocin secretion in dehydrated rats

Brain-derived angiotensin II (ANG II) and prostaglandins have important roles in the regulation of body fluid and blood pressure homeostasis. In the present studies we investigated the central interactions between these two neurochemical products in regulating the hypothalamo-neurohypophysial system during dehydration. Intracerebroventricular (icv) administration of prostaglandin D(2) (PGD(2); 20 microg/5 microl) to conscious adult male Sprague-Dawley rats deprived of water for 24 h did not alter significantly the already elevated plasma levels of vasopressin or oxytocin. When PGD(2) was administered in combination with losartan, an antagonist of ANG II AT(1)-receptor subtype, however, concentrations of both hormones in plasma became further elevated. Icv administration of ANG II (50 ng/5 microl) increased further the enhanced plasma levels of vasopressin and oxytocin, as expected. Pretreatment with indomethacin (200 microg/5 microl; icv), an inhibitor of cyclo-oxygenase, significantly attenuated the ANG II-induced increase in oxytocin secretion only. Independent of the presence of ANG II, however, indomethacin decreased plasma levels of vasopressin, but not oxytocin. These results indicate that a prostaglandin is required for the stimulated release of vasopressin during dehydration and that the elevation of oxytocin secretion in response to ANG II depends largely on activation of cyclo-oxygenase and production of prostaglandins. The oxytocin response to exogenously administered PGD(2), however, can be negatively modulated by a mechanism dependent upon ANG II AT(1) receptors.

Cytochalasin B modulation of Caco-2 tight junction barrier: role of myosin light chain kinase

The intracellular mechanisms that mediate cytochalasin-induced increase in intestinal epithelial tight junction (TJ) permeability are unclear. In this study, we examined the involvement of myosin light chain kinase (MLCK) in this process, using the filter-grown Caco-2 intestinal epithelial monolayers. Cytochalasin B (Cyto B) (5 microg/ml) produced an increase in Caco-2 MLCK activity, which correlated with the increase in Caco-2 TJ permeability. The inhibition of Cyto B-induced MLCK activation prevented the increase in Caco-2 TJ permeability. Additionally, myosin-Mg(2+)-ATPase inhibitor and metabolic inhibitors (which inhibit MLCK induced actin-myosin contraction) also prevented the Cyto B-induced increase in Caco-2 TJ permeability. Cyto B caused a late-phase (15-30 min) aggregation of actin fragments into large actin clumps, which was also inhibited by MLCK inhibitors. Cyto B produced a morphological disturbance of the ZO-1 TJ proteins, visually correlating with the functional increase in Caco-2 TJ permeability. The MLCK and myosin-Mg(2+)-ATPase inhibitors prevented both the functional increase in TJ permeability and disruption of ZO-1 proteins. These findings suggested that Cyto B-induced increase in Caco-2 TJ permeability is regulated by MLCK activation.

Indomethacin prevents the L-NAME-induced increase in plasma levels of oxytocin in dehydrated rats

Inhibiting NO synthase (NOS) with N(G)-nitro-L-arginine methyl ester (L-NAME, 250 microg/5 microl of artificial cerebrospinal fluid (aCSF)) injected intracerebroventricularly (i.c.v.) increased already enhanced levels of oxytocin, but not vasopressin, in conscious adult male Sprague-Dawley rats dehydrated for 24 h. Intracerebroventricular pretreatment with indomethacin (200 microg/5 microl aCSF), an inhibitor of cyclo-oxygenase, but not with losartan (25 microg/5 microl aCSF), an antagonist of angiotensin II (ANG II) AT(1)-receptor subtype, nearly prevented the elevation in oxytocin levels after L-NAME. Thus, NO inhibits prostaglandin (but not ANG II) mediated the modulatory actions of NO on oxytocin secretion from the hypothalamo-neurohypophysial system (HNS) during water deprivation.

Adeno-associated virus mediated gene transfer into primary rat brain neuronal and glial cultures: enhancement with the pH-sensitive surfactant dodecyl 2-(1'-imidazolyl) propionate

This study evaluated the effects of a novel, pH-sensitive surfactant, dodecyl 2-(1'-imidazolyl) propionate (DIP), on cationic lipid mediated transfection in primary rat brain neuronal and glial cultures. The cationic lipid complex DOTAP/DOPE (1, 2-dioleoyl-3-trimethylammonium propionate and dioleoyl phosphatidylethanolamine, respectively) was added over a range of concentrations (0-120 microg/ml) with DNA concentration kept constant (1.6 microg/ml). The neuron-specific enolase (NSE) and cytomegalovirus (CMV) promoters were found to drive green fluorescent protein (GFP) expression in neuron-enriched and glial cultures, respectively, using adeno-associated virus (AAV) derived constructs. NSE-driven GFP expression was not observed in glial cultures. Addition of DOTAP/DOPE increased transfection efficiency over a wide range of lipid concentrations (5-50 microg/ml) keeping DNA concentration constant (1.6 microg/ml). Addition of DIP to the lipid/DNA complex increased maximum transfection efficiencies in glial and neuronal cultures 2-3-fold. Transfection efficiencies were at their maximum with a similar total lipid concentration (50 microg/ml) in both cell-types in the presence of DIP. Neuronal cultures were more sensitive than glia to the toxic actions of DOTAP/DOPE, with or without DIP. These results indicate that AAV-mediated gene-transfer to neurons and glia can be facilitated by addition of a pH-sensitive surfactant to cationic liposome/DNA complexes and that endosomal escape could be a limiting factor in transgene expression.

Ethanol modulation of intestinal epithelial tight junction barrier

Previous studies have shown that high concentrations of ethanol (>/=40%) cause functional damage of the gastrointestinal epithelial barrier by direct cytotoxic effect on the epithelial cells. The effects of lower noncytotoxic doses of ethanol on epithelial barrier function are unknown. A major function of gastrointestinal epithelial cells is to provide a barrier against the hostile substances in the gastrointestinal lumen. The apicolaterally located tight junctions (TJs) form a paracellular seal between the lateral membranes of adjacent cells and act as a paracellular barrier. In this study, we investigated the effects of lower doses of ethanol on intestinal epithelial TJ barrier function using filter-grown Caco-2 intestinal epithelial monolayers. The Caco-2 TJ barrier function was assessed by measuring epithelial resistance or paracellular permeability of the filter-grown monolayers. Ethanol (0, 1, 2.5, 5, 7.5, and 10%) produced a dose-related drop in Caco-2 epithelial resistance and increase in paracellular permeability. Ethanol also produced a progressive disruption of TJ protein (ZO-1) with separation of ZO-1 proteins from the cellular junctions and formation of large gaps between the adjacent cells. Ethanol, at the doses used (</=10%), did not cause cytotoxicity (lactate dehydrogenase release) to the Caco-2 cells. Ethanol produced a disassembly and displacement of perijunctional actin and myosin filaments from the perijunctional areas. On ethanol removal, actin and myosin filaments rapidly reassembled at the cellular borders. Ethanol stimulated the Caco-2 myosin light chain kinase (MLCK) activity but did not affect the MLCK protein levels. Specific MLCK inhibitor ML-7 inhibited both ethanol increases in MLCK activity and TJ permeability without affecting the MLCK protein levels. Consistent with these findings, metabolic inhibitors sodium azide and 2,4-dinitrophenol significantly prevented ethanol-induced increase in Caco-2 TJ permeability, whereas cycloheximide or actinomycin D had no effect. The results of this study indicate that ethanol at low noncytotoxic doses causes a functional and structural opening of the Caco-2 intestinal epithelial TJ barrier by activating MLCK.

Malignant intraperitoneal neoplasms of childhood

OBJECTIVE

The purpose of this paper is to review and categorize the CT appearances of primary and secondary intraperitoneal neoplasms in children.

MATERIALS AND METHODS

We retrospectively reviewed the CT images of 14 cases of intraperitoneal neoplasms. They were reviewed for bowel wall thickening, mesenteric nodules, ascites, calcification, peritoneal nodules, omental caking, and contrast enhancement.

RESULTS

Computed tomography images of 14 cases of intraperitoneal neoplasms were evaluated: rhabdomyosarcoma (5), lymphoma (3), neuroblastoma (2), germ cell tumor (1), mesothelioma (1), Wilms tumor (1), and hepatocellular carcinoma (1). Nodular enhancement was seen in all cases, ascites in most, significant bowel wall thickening only with lymphoma, and calcification only with germ cell tumors. Omental caking was present both with rhabdomyosarcoma and lymphoma.

CONCLUSIONS

While rare in pediatrics, intraperitoneal neoplasms occur in children, and CT is useful in identifying these peritoneal neoplasms.

Effects of central injection of kyotorphin and L-arginine on oxytocin and vasopressin release and blood pressure in conscious rats

Intracerebroventricular (I.C.V.) administration of an inhibitor of nitric oxide synthase (NOS) increases oxytocin but not vasopressin secretion, in dehydrated rats [38]. Surprisingly, central injection of L-arginine, the substrate for NOS, caused a similar effect. Kyotorphin (L-tyrosyl-L-arginine), a dipeptide formed from L-arginine by kyotorphin synthetase in the brain may mediate this magnocellular response. Therefore, the dose and time responses of hormone release were compared following I.C.V. injection of kyotorphin and L-arginine to conscious rats that were normally hydrated or deprived of water for 24 h. In water-sated rats, both L-arginine and kyotorphin increased blood pressure and plasma glucose levels coincident with elevating circulating levels of oxytocin, but not vasopressin. In dehydrated animals, both L-arginine and kyotorphin increased plasma oxytocin levels with a similar time course but only kyotorphin decreased vasopressin release. D-arginine, like L-arginine, stimulated secretion of oxytocin, indicating a nonstereospecific effect. A kyotorphin receptor antagonist (L-leucyl-L-arginine) given I.C.V. to dehydrated animals elevated plasma oxytocin and prevented the decrease in vasopressin levels after kyotorphin. Thus, kyotorphin, but not L-arginine, appears to attenuate release of vasopressin either directly from magnocellular neurons or indirectly via modulating compensatory reflexes activated by the pressor response. On the other hand, an excess of L-arginine and kyotorphin within the CNS may mimic the stress response by augmenting release of oxytocin and activating the sympathetic nervous system to increase blood pressure and plasma glucose levels.

Effects of L-NAME on cerebral metabolic, vasopressin, oxytocin, and blood pressure responses in hemorrhaged rats

NG-nitro-L-arginine methyl ester (L-NAME; 250 micrograms/5 microliters), an inhibitor of NO synthase, or the vehicle artificial cerebrospinal fluid (aCSF; 5 microliters) was administered intracerebroventricularly to conscious rats hemorrhaged (0.7 ml/min) to a 20% volume depletion. Hypotension was maximal 5 min after hemorrhage ended, with compensatory recovery to basal levels 20 min later, regardless of drug treatment. L-NAME, however, elevated (P < 0.05) blood pressure (vs. aCSF controls) 40-45 min after intracerebroventricular administration. In normovolemic rats, L-NAME produced a significant pressor response and increased plasma levels of vasopressin (VP) and oxytocin (OT). After hemorrhage, both hormone levels increased, but only OT was further enhanced by L-NAME. Thus centrally produced NO tonically inhibits OT and VP secretion under basal normovolemic conditions and selectively inhibits OT release during hypovolemia. Hemorrhage increased the rates of glucose utilization in the neural lobe, indicative of enhanced efferent neural functional activity. L-NAME further enhanced the metabolic activity in the entire hypothalamoneurohypophysial system of hemorrhaged animals. Several other brain structures involved in the regulation of blood pressure and the stress response were also metabolically affected by the hemorrhage and L-NAME.

Nitric oxide control of drinking, vasopressin and oxytocin release and blood pressure in dehydrated rats

Intracerebroventricular (i.c.v.) injection of the inhibitor of NO synthase (NOS), N(G)-nitro-L-arginine methyl ester (L-NAME) (250 microg/5 microL) attenuated the drinking response in rats deprived of water for 24 h. Moreover, oxytocin (OT) levels in plasma increased after 2 min, whereas both oxytocin and vasopressin levels were elevated at 120 min after intracerebroventricular injection. The delayed effect of L-NAME on both hormones was not observed in dehydrated animals allowed to drink water. Blood pressure remained stable after injection of artificial cerebrospinal fluid (aCSF) in dehydrated rats not allowed to drink. In rats having access to water, however, there was an immediate but transient pressor response (0-5 min) with a delayed hypotension from 45 to 120 min. L-NAME consistently increased blood pressure in a biphasic mode, whether the animals drank or not, with an early peak at 5 min that decayed after 15-30 min and a second pressor response beginning at 30-45 min and remaining elevated at 120 min when the experiment ended. These pressor responses were independent of the adrenal glands. Thus, centrally produced nitric oxide facilitates drinking, inhibits release of vasopressin and oxytocin from the magnocellular system, and maintains resting arterial blood pressure in normally hydrated and dehydrated rats.

Role of NO on vasopressin and oxytocin release and blood pressure responses during osmotic stimulation in rats

NG-nitro-L-arginine methyl ester (L-NAME, 250 micrograms/5 microliters), an inhibitor of nitric oxide (NO) synthase, or artificial cerebrospinal fluid (5 microliters) was administered intracerebroventricularly to conscious naive rats or to rats treated subcutaneously (15 microliters/kg) with NaCl (0.15, 0.45, or 1.0 M) or given a needle prick only. Intracerebroventricular injection of L-NAME increased plasma concentration of vasopressin (VP) and oxytocin (OT) in control naive rats, indicating that NO tonically inhibits basal secretion of both hormones during isosmotic isovolemic conditions. Osmotic stimulation with hypertonic saline (0.45 and 1.0 M NaCl) elevated plasma levels of both hormones as expected. Central blockade of NO synthase further enhanced secretion of OT during mild, but not strong, osmotic stimulation, whereas the high levels of VP remained unaffected by L-NAME. In animals treated with the needle prick or 0.15 M NaCl, only OT levels were increased after L-NAME. Therefore, NO selectively inhibits OT release in response to a painful stimulus (needle prick) and moderate osmotic stimulation to promote a preferential release of VP. A transient pressor response was observed after subcutaneous injection of 0.15 and 0.45 M NaCl, but a sustained response was obtained after 1.0 M NaCl. Regardless of whether the animals received NaCl solutions, however, treatment with L-NAME elevated blood pressure in all animals. Thus NO-induced vasodilation maintains basal arterial blood pressure and limits the pressor response to osmotic stimulation.

NO and angiotensin II effects on blood pressure and fluid homeostasis

Angiotensin II (50 ng/5 microl) and L-NAME (250 microg/5 microl), an inhibitor of NO synthase (NOS), were administered intracerebroventricularly alone or in combination to conscious rats. Mean arterial blood pressure (MABP) increased reaching a peak within 5 min in all groups compared to controls treated with the vehicle, artificial CSF (5 microl). MABP returned to basal levels at 30 min after angiotensin II and remained stable for the following 90 min. In animals treated with L-NAME alone, after the initial pressor response, MABP declined but began to increase progressively from 30 min until the end of the experiment at 120 min. When administered with angiotensin II, however, the initial pressor response was prolonged. Angiotensin II-induced drinking was significantly attenuated by L-NAME. In control rats, inhibiting NOS elevated plasma levels of oxytocin and vasopressin but in angiotensin II-stimulated animals, only oxytocin was further elevated after L-NAME. Thus, NO formed centrally inhibits basal secretion of oxytocin and vasopressin as well as the resting blood pressure. During stimulation with angiotensin II, NO facilitates drinking, limits the pressor response and selectively inhibits oxytocin release.

Central inhibition of nitric oxide synthase preferentially augments release of oxytocin during dehydration

Intracerebroventricular (i.c.v.) administration of NG-monomethyl-L-arginine monoacetate (NMMA; 500 micrograms; 402 mM) and NG-nitro-L-arginine methyl ester (NAME; 270 micrograms; 200 mM), inhibitors of nitric oxide synthase, enhanced the rise in oxytocin but not vasopressin levels in plasma of conscious rats following 24 h of water deprivation. This effect of NMMA occurred by 10 min after administration, reached its peak at 15 min and decreased by 20 min. Daily administration of lower doses (50 micrograms and 0.5 microgram/5 microliter, i.c.v.) of another inhibitor of nitric oxide synthase, NG-nitro-L-arginine, just before and after 24 h of water deprivation and in control animals treated similarly were without effect on either vasopressin or oxytocin levels. Nitric oxide, therefore, attenuates preferentially the release of oxytocin during dehydration.

Anterior and posterior spinal fusion. Staged versus same-day surgery

Seventy-five patients who underwent combined anterior and posterior spinal fusion were compared to evaluate the results and safety of staged vs. continuous anterior and posterior spinal fusion. Thirty-five patients underwent two-stage anterior and posterior spinal fusion. The first stage consisted of anterior release; the second stage, which took place 7-10 days later, consisted of posterior spinal fusion and instrumentation. Forty patients underwent continuous anterior and posterior spinal fusion. This procedure consisted of anterior release followed by immediate posterior spinal fusion and instrumentation. The results show that 1) a continuous procedure is faster than the staged procedure; 2) there is less blood loss; 3) fewer days are spent in the hospital; and 4) better correction of the spinal deformity is achieved. Also, the complications were less frequent and less severe with the continuous procedure. It was concluded that the continuous procedure is safe and efficacious and has several advantages over the staged procedure.