Lower Gastrointestinal Hemorrhage

This JAMA Clinical Guidelines Synopsis summarizes the 2023 American College of Gastroenterology guidelines on management of patients with acute lower gastrointestinal bleeding.

Falls Prevention for Older Adults

This article summarizes a 2022 clinical practice guideline on falls prevention and management in older adults from the World Falls Guidelines Initiative.

2023 Update in ambulatory general internal medicine

The practice of outpatient medicine is demanding, encompasses a wide scope of practice, and leaves little time for internists to stay up to date with the current literature. This article reviews 5 studies published in 2022 and 2023 that have the potential to change the practice of outpatient medicine. Topics covered include chronic kidney disease, secondary cardiovascular disease, kidney stones, obesity, and lipid management.

Topical Therapies for Atopic Dermatitis

This JAMA Clinical Guidelines Synopsis summarizes the American Academy of Dermatology’s 2023 guidelines for topical-therapy management of adults with atopic dermatitis.

Validity of the Childhood Asthma Control Test in diverse populations: A systematic review

PURPOSE

We examined the validity of the Childhood Asthma Control Test (C-ACT) and identified recommended thresholds for uncontrolled asthma in children from varying backgrounds.

METHODS

A systematic literature review was performed utilizing PubMed, Ovid Medline, SCOPUS, CINAHL, and conference proceedings. Studies were included if they enrolled children, had a primary outcome of asthma control, examined test validity or psychometrics, and utilized the C-ACT. Along with study design and demographic data, we extracted all outcomes and comparisons used to validate the C-ACT. We evaluated risk of bias using the COSMIN Risk of Bias tool. Our protocol was registered with PROSPERO (CRD42020211119).

RESULTS

Of 4924 records screened, 28 studies were included. Studies were conducted internationally and published between 2007 and 2018. Average number of enrolled participants was 193 (SD = 155, range = 22-671). Ten studies calculated Cronbach's α (mean [SD] = 0.78(0.05), range = 0.677-0.83). Thirteen studies recommended cut-offs for uncontrolled asthma (≤18-≤24). Nine studies found significant agreement or correlation between C-ACT and Global Initiative for Asthma guidelines/physician assessment of asthma control (correlation coefficients range = 0.219-0.65). Correlation coefficients between C-ACT and spirometry were <0.6 in five of six studies that included spirometry. Kappa values for C-ACT and various spirometry measurements ranged 0.00-0.34.

CONCLUSIONS

The C-ACT showed good internal consistency and mixed levels of agreement and correlation with various clinical asthma measures. Recommended cut-offs for asthma control varied and had no consistent relationship with nationality, race, ethnicity, or language. Few studies examined cross-cultural validity and multiple populations remain under-studied.

Prescribing Opioids for Pain

This JAMA Clinical Guidelines Synopsis summarizes the Centers for Disease Control and Prevention’s 2022 clinical practice guideline for prescribing opioids for pain.

Endocrine Society Hypercalcemia of Malignancy Guidelines

This guideline synopsis summarizes the Endocrine Society guidelines for hypercalcemia of malignancy in adults.

Longer-term Benefits and Risks of Sodium-Glucose Cotransporter-2 Inhibitors in Type 2 Diabetes: a Systematic Review and Meta-analysis

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2Is) are a recent class of medication approved for the treatment of type 2 diabetes (T2D). Previous meta-analyses have quantified the benefits and harms of SGLT2Is; however, these analyses have been limited to specific outcomes and comparisons and included trials of short duration. We comprehensively reviewed the longer-term benefits and harms of SGLT2Is compared to placebo or other anti-hyperglycemic medications.

METHODS

We searched PubMed, Scopus, and clinicaltrials.gov from inception to July 2019 for randomized controlled trials of minimum 52 weeks' duration that enrolled adults with T2D, compared an SGLT2I to either placebo or other anti-hyperglycemic medications, and reported at least one outcome of interest including cardiovascular risk factors, microvascular and macrovascular complications, mortality, and adverse events. We conducted random effects meta-analyses to provide summary estimates using weighted mean differences (MD) and pooled relative risks (RR). The study was registered a priori with PROSPERO (CRD42018090506).

RESULTS

Fifty articles describing 39 trials (vs. placebo, n = 28; vs. other anti-hyperglycemic medication, n = 12; vs. both, n = 1) and 112,128 patients were included in our analyses. Compared to placebo, SGLT2Is reduced cardiovascular risk factors (e.g., hemoglobin A1c, MD - 0.55%, 95% CI - 0.62, - 0.49), macrovascular outcomes (e.g., hospitalization for heart failure, RR 0.70, 95% CI 0.62, 0.78), and mortality (RR 0.87, 95% CI 0.80, 0.94). Compared to other anti-hyperglycemic medications, SGLT2Is reduced cardiovascular risk factors, but insufficient data existed for other outcomes. About a fourfold increased risk of genital yeast infections for both genders was observed for comparisons vs. placebo and other anti-hyperglycemic medications.

DISCUSSION

We found that SGLT2Is led to durable reductions in cardiovascular risk factors compared to both placebo and other anti-hyperglycemic medications. Reductions in macrovascular complications and mortality were only observed in comparisons with placebo, although trials comparing SGLT2Is vs. other anti-hyperglycemic medications were not designed to assess longer-term outcomes.

The Longer-Term Benefits and Harms of Glucagon-Like Peptide-1 Receptor Agonists: a Systematic Review and Meta-Analysis

BACKGROUND

Previous meta-analyses of the benefits and harms of glucagon-like peptide-1 receptor agonists (GLP1RAs) have been limited to specific outcomes and comparisons and often included short-term results. We aimed to estimate the longer-term effects of GLP1RAs on cardiovascular risk factors, microvascular and macrovascular complications, mortality, and adverse events in patients with type 2 diabetes, compared to placebo and other anti-hyperglycemic medications.

METHODS

We searched PubMed, Scopus, and clinicaltrials.gov (inception-July 2019) for randomized controlled trials ≥ 52 weeks' duration that compared a GLP1RA to placebo or other anti-hyperglycemic medication and included at least one outcome of interest. Outcomes included cardiovascular risk factors, microvascular and macrovascular complications, all-cause mortality, and treatment-related adverse events. We performed random effects meta-analyses to give summary estimates using weighted mean differences (MD) and pooled relative risks (RR). Risk of bias was assessed using the Cochrane Collaboration risk of bias in randomized trials tool. Quality of evidence was summarized using the Grading of Recommendations, Assessment, Development, and Evaluation approach. The study was registered a priori with PROSPERO (CRD42018090506).

RESULTS

Forty-five trials with a mean duration of 1.7 years comprising 71,517 patients were included. Compared to placebo, GLP1RAs reduced cardiovascular risk factors, microvascular complications (including renal events, RR 0.85, 0.80-0.90), macrovascular complications (including stroke, RR 0.86, 0.78-0.95), and mortality (RR 0.89, 0.84-0.94). Compared to other anti-hyperglycemic medications, GLP1RAs only reduced cardiovascular risk factors. Increased gastrointestinal events causing treatment discontinuation were observed in both comparisons.

DISCUSSION

GLP1RAs reduced cardiovascular risk factors and increased gastrointestinal events compared to placebo and other anti-hyperglycemic medications. GLP1RAs also reduced MACE, stroke, renal events, and mortality in comparisons with placebo; however, analyses were inconclusive for comparisons with other anti-hyperglycemic medications. Given the high costs of GLP1RAs, the lack of long-term evidence comparing GLP1RAs to other anti-hyperglycemic medications has significant policy and clinical practice implications.

Red blood cells stored for increasing periods produce progressive impairments in nitric oxide-mediated vasodilation

BACKGROUND

Clinical outcomes in transfused patients may be affected by the duration of blood storage, possibly due to red blood cell (RBC)-mediated disruption of nitric oxide (NO) signaling, a key regulator of vascular tone and blood flow.

STUDY DESIGN AND METHODS

AS-1 RBC units stored up to 42 days were sampled at selected storage times. Samples were added to aortic rings ex vivo, a system where NO-mediated vasodilation could be experimentally controlled.

RESULTS

RBC units showed storage-dependent changes in plasma hemoglobin (Hb), RBC 2,3-diphosphoglycerate acid, and RBC adenosine triphosphate conforming to expected profiles. When freshly collected (Day 0) blood was added to rat aortic rings, methacholine (MCh) stimulated substantial NO-mediated vasodilation. In contrast, MCh produced no vasodilation in the presence of blood stored for 42 days. Surprisingly, the vasoinhibitory effects of stored RBCs were almost totally mediated by RBCs themselves: removal of the supernatant did not attenuate the inhibitory effects, while addition of supernatant alone to the aortic rings only minimally inhibited MCh-stimulated relaxation. Stored RBCs did not inhibit vasodilation by a direct NO donor, demonstrating that the RBC-mediated vasoinhibitory mechanism did not work by NO scavenging.

CONCLUSIONS

These studies have revealed a previously unrecognized vasoinhibitory activity of stored RBCs, which is more potent than the described effects of free Hb and works through a different mechanism that does not involve NO scavenging but may function by reducing endothelial NO production. Through this novel mechanism, transfusion of small volumes of stored blood may be able to disrupt physiologic vasodilatory responses and thereby possibly cause adverse clinical outcomes.

Red blood cells stored for increasing periods produce progressive impairments in nitric oxide-mediated vasodilation

BACKGROUND

Clinical outcomes in transfused patients may be affected by the duration of blood storage, possibly due to red blood cell (RBC)-mediated disruption of nitric oxide (NO) signaling, a key regulator of vascular tone and blood flow.

STUDY DESIGN AND METHODS

AS-1 RBC units stored up to 42 days were sampled at selected storage times. Samples were added to aortic rings ex vivo, a system where NO-mediated vasodilation could be experimentally controlled.

RESULTS

RBC units showed storage-dependent changes in plasma hemoglobin (Hb), RBC 2,3-diphosphoglycerate acid, and RBC adenosine triphosphate conforming to expected profiles. When freshly collected (Day 0) blood was added to rat aortic rings, methacholine (MCh) stimulated substantial NO-mediated vasodilation. In contrast, MCh produced no vasodilation in the presence of blood stored for 42 days. Surprisingly, the vasoinhibitory effects of stored RBCs were almost totally mediated by RBCs themselves: removal of the supernatant did not attenuate the inhibitory effects, while addition of supernatant alone to the aortic rings only minimally inhibited MCh-stimulated relaxation. Stored RBCs did not inhibit vasodilation by a direct NO donor, demonstrating that the RBC-mediated vasoinhibitory mechanism did not work by NO scavenging.

CONCLUSIONS

These studies have revealed a previously unrecognized vasoinhibitory activity of stored RBCs, which is more potent than the described effects of free Hb and works through a different mechanism that does not involve NO scavenging but may function by reducing endothelial NO production. Through this novel mechanism, transfusion of small volumes of stored blood may be able to disrupt physiologic vasodilatory responses and thereby possibly cause adverse clinical outcomes.

Increased caloric intake on a fat-rich diet: role of ovarian steroids and galanin in the medial preoptic and paraventricular nuclei and anterior pituitary of female rats

Previous studies in male rats have demonstrated that the orexigenic peptide galanin (GAL), in neurones of the anterior parvocellular region of the paraventricular nucleus (aPVN) projecting to the median eminence (ME), is stimulated by consumption of a high-fat diet and may have a role in the hyperphagia induced by fat. In addition to confirming this relationship in female rats and distinguishing the aPVN-ME from other hypothalamic areas, the present study identified two additional extra-hypothalamic sites where GAL is stimulated by dietary fat in females but not males. These sites were the medial preoptic nucleus (MPN), located immediately rostral to the aPVN, and the anterior pituitary (AP). The involvement of ovarian steroids, oestradiol (E(2)) and progesterone (PROG), in this phenomenon was suggested by an observed increase in circulating levels of these hormones and GAL in MPN and AP with fat consumption and an attenuation of this effect on GAL in ovariectomised (OVX) rats. Furthermore, in the same four areas affected by dietary fat, levels of GAL mRNA and peptide immunoreactivity were stimulated by E(2) and further by PROG replacement in E(2)-primed OVX rats and were higher in females compared to males. Because both GAL and PROG stimulate feeding, their increase on a fat-rich diet may have functional consequences in females, possibly contributing to the increased caloric intake induced by dietary fat. This is supported by the findings that PROG administration in E(2)-primed OVX rats reverses the inhibitory effect of E(2) on total caloric intake while increasing voluntary fat ingestion, and that female rats with higher GAL exhibit increased preference for fat compared to males. Thus, ovarian steroids may function together with GAL in a neurocircuit, involving the MPN, aPVN, ME and AP, which coordinate feeding behaviour with reproductive function to promote consumption of a fat-rich diet at times of increased energy demand.

Meal pattern analysis of macronutrient intake after PVN norepinephrine and peripheral clonidine administration

Norepinephrine (NE) injected into the paraventricular nucleus (PVN) of the hypothalamus of rats is a potent stimulant of food intake, more specifically ingestion of the carbohydrate nutrient. In 2 experiments of the present study, this effect was found to be dose-dependent, and the effectiveness of NE in potentiating total food consumption was greatly reduced when the carbohydrate diet was removed. In addition, experiments using a computer-automated data acquisition apparatus were performed to characterize, in detail, the impact of PVN injection of NE and peripheral administration of the alpha2-noradrenergic agonist clonidine (CLON) on the macrostructure of feeding behavior in animals given 3 pure macronutrient diets. These 2 compounds, injected at the onset of the nocturnal feeding cycle, had very similar effects on meal patterns, with both affecting nutrient intake by increasing meal size and duration rather than by increasing meal frequency. They both affected primarily the first meal of the dark cycle, selectively enhancing carbohydrate ingestion by increasing Kcal intake, percent composition in the total diet and feeding time, and also by decreasing the satiating impact of this macronutrient. These stimulatory effects of NE and CLON on carbohydrate ingestion during the first meal were followed by complete recovery over the next 1 to 2 hours after injection. In addition to these predominant effects on carbohydrate intake, PVN NE at the highest doses tested (10 and 20 nmoles) produced a small increase in fat intake, whereas peripheral CLON actually decreased intake of fat and protein over the 12-hour cycle. The similarities in the impact of NE and CLON on carbohydrate feeding patterns support the hypothesis that both agonists may be acting via the same PVN alpha2-noradrenergic system controlling ingestion of the carbohydrate-rich meals which predominate at dark onset.

Hypothalamic serotonin in control of eating behavior, meal size, and body weight

Serotonin (5-HT) has been implicated in the control of eating behavior and body weight. Stimulants of this monoamine reduce food intake and weight gain and increase energy expenditure, both in animals and in humans. This article reviews evidence that supports a role for hypothalamic serotonergic receptor mechanisms in the mediation of these effects. A variety of studies in rodents indicate that, at low doses, 5-HT or drugs that enhance the release of this neurotransmitter preferentially inhibit the ingestion of carbohydrate, more than fat or protein. This phenomenon is mediated, in part, by 5-HT receptors located in various medial hypothalamic nuclei. A negative feedback loop exists between the consumption of this macronutrient and the turnover of 5-HT in the hypothalamus. That is, carbohydrate ingestion enhances the synthesis and release of hypothalamic 5-HT, which in turn serves to control the size of carbohydrate-rich meals. A model is described that proposes the involvement of circulating hormones and glucose in this feedback process. These hormones, including insulin, corticosterone, and the adipose tissue-derived hormone, leptin, have impact on serotonergic function as well as satiety. This model further suggests that 5-HT exerts its strongest effect on appetite at the start of the natural feeding cycle, when carbohydrate is normally preferred. Clinical studies provide evidence that is consistent with the proposed model and that implicates 5-HT in disturbances of eating and body weight disorders.

Hypothalamic galanin: control by signals of fat metabolism

The peptide, galanin (GAL), is known to stimulate eating behavior, reduce energy expenditure and affect the release of metabolic hormones. Further, the activity of this peptide in the hypothalamus is modulated, in turn, by these hormones as well as by the ingestion of nutrients. The focus of this investigation is on signals related to nutrient metabolism that may also affect GAL production and, through these neurochemical events, control the ingestion of specific nutrients. Three experiments were performed in normal-weight male, Sprague-Dawley rats. In Experiment 1, the impact of food deprivation (24 and 48 h) was examined. Experiment 2 tested the effects of the compound, 2-deoxy-D-glucose (2-DG, 200 and 400 mg/kg), which blocks glucose utilization, whereas Experiment 3 studied mercaptoacetate (MA, 200 and 600 micromol/kg), which blocks fatty acid oxidation. Eating behavior was examined in some rats, whereas hypothalamic GAL activity was measured in others using radioimmunoassay, immunohistochemistry and in situ hybridization. Both food deprivation and MA (600 micromol/kg), but not 2-DG, affected GAL in the hypothalamus, in one specific area. This is the anterior parvocellular region of the paraventricular nucleus (aPVN), which has a dense concentration of GAL-containing neurons and terminals. GAL gene expression and peptide immunoreactivity in this area is enhanced by food deprivation; in contrast, it is reduced by injection of MA. Other hypothalamic sites with dense concentrations of GAL-containing neurons or fibers are unaffected by food deprivation or MA, and the antimetabolite 2-DG has no impact on GAL in any area. Behavioral measurements indicate that these shifts in GAL activity are accompanied by specific changes in eating behavior. Food deprivation which enhances aPVN GAL produces a marked increase in fat ingestion, whereas MA which reduces aPVN GAL causes a specific reduction in fat ingestion along with a stimulation of protein intake. In contrast, 2-DG preferentially enhances ingestion of carbohydrate. These findings suggest a possible relationship between GAL activity in the aPVN and the metabolic and behavioral processes of fat metabolism and ingestion.

Neuropeptide Y in relation to carbohydrate intake, corticosterone and dietary obesity

Neuropeptide Y (NPY) is known to stimulate eating behavior and to be related to behavioral patterns of carbohydrate ingestion. The present report investigates this relationship further to: (1) characterize the specific NPY projection activated in different dietary paradigms; (2) understand associated changes in circulating hormones that may mediate dietary effects on NPY neurons; and (3) determine whether endogenous NPY in conditions with macronutrient diets can be linked to body fat. Male albino Sprague-Dawley rats were tested in two feeding paradigms, one in which the rats were given a choice of the macronutrients, carbohydrate, fat or protein, or the other involving a single diet varying in carbohydrate of fat content. These studies consistently demonstrated a close association between the ingestion of carbohydrate and NPY levels, specifically in the arcuate nucleus (ARC) and medial portion of the paraventricular nucleus (PVN) of the hypothalamus. In addition to revealing increased NPY activity in animals that naturally select high carbohydrate when given a choice of macronutrients, a single diet with 65% carbohydrate (10% fat), compared to a control diet with 45% carbohydrate (30% fat), significantly potentiates NPY gene expression and NPY-immunoreactivity, as determined by in situ hybridization and immunohistochemistry. A further lowering of carbohydrate to 15% has little effect on NPY. Studies of medial hypothalamic fragments in vitro also reveal enhanced NPY release from hypothalamic tissue taken from rats maintained on high-carbohydrate diet. Together with NPY, circulating corticosterone (CORT) levels are also highest in a high-carbohydrate condition and positively correlated with NPY in the ARC. An association between NPY and adiposity in these dietary conditions is indicated by significantly higher levels of NPY in the medial PVN in rats with high body fat, whether consuming a high-carbohydrate of high-fat diet. This evidence, linking NPY to carbohydrate intake and circulating CORT, suggests a role for this peptide in glucose homeostasis that is normally exhibited under conditions when carbohydrate stores are low. Disturbances in this homeostatic process, associated with hyperinsulinemia and higher levels of NPY, become evident with only a moderate rise in body fat on a high-carbohydrate as well as high-fat diet.

Behavioral and endocrine traits of obesity-prone and obesity-resistant rats on macronutrient diets

Patterns of eating behavior, body weight gain, and hormone changes were examined in normal-weight albino Sprague-Dawley rats on macronutrient diets. These diets consisted of either three separate jars with pure macronutrients, fat, carbohydrate and protein, from which to choose, or a single diet with different concentrations of fat and carbohydrate. Similar patterns on the choice-diet and single-diet paradigms were observed. During the first 7-10 days on these diets but not subsequently, the rats consuming a fat-rich diet exhibit significant hyperphagia, an increase in both total and fat intake that produces higher body weight gain. Compared with a 10% fat diet, a 30% fat diet is associated with a decline in insulin and corticosterone (CORT) levels, whereas a 60% fat diet produces an increase in circulating glucose. Levels of glucose are positively correlated with fat intake, and together these measures are consistently related to body fat. These relationships are most strongly expressed in rats that consume a fat-rich diet with >30% fat. Whereas insulin levels are also positively related to body fat, CORT is inversely related in these normal-weight subjects. In animals consuming a high-fat diet, a clear separation can be seen between "obesity-prone" (OP) rats with 100% greater body fat than "obesity-resistant" (OR) rats. The OP rats, which consume 15% more total calories, have significantly higher insulin and glucose levels. In animals that consume a diet with >30% fat, it is the OP but not the OR rats that exhibit a positive relation between fat intake, glucose levels, and body fat and reveal an additional association between carbohydrate intake, insulin, and body fat. Thus these rats on macronutrient diets exhibit distinct traits that relate behavior to hormone disturbances and adiposity and distinguish subjects that are prone vs. resistant to obesity.

Gonadal steroids and hypothalamic galanin and neuropeptide Y: role in eating behavior and body weight control in female rats

The neuropeptides, galanin (GAL) and neuropeptide Y (NPY), based on studies in male rodents, are believed to have a role in controlling energy balance, both nutrient ingestion and metabolism. Whereas these peptides are also involved in reproduction, little is known about their specific function in energy balance in females. In rats consuming lab chow or macronutrient diets, measurements across the estrous cycle were taken of hypothalamic GAL and NPY, using RIA and immunohistochemistry; of the circulating hormones, estradiol, progesterone, and LH; and also of food intake and body weight. Levels of GAL and NPY peak during the proestrous phase of the female cycle when circulating estradiol and progesterone also rise. As previously reported for GAL, this peak is detected in two areas, the medial preoptic area (MPOA; +110%; P < 0.05) and the external zone of the median eminence (+57%; P < 0.05). In addition, this proestrous peak is seen in the paraventricular nucleus (PVN), specifically the anterior parvocellular portion (+35%; P < 0.05). Similarly, NPY rises during proestrous in the medial region of the PVN (+21%; P < 0.05) in addition to the MPOA (+78%; P < 0.05) and arcuate nucleus (+35%; P < 0.05). This peak in peptide levels is accompanied by an increase in caloric intake in rats receiving the lab chow diet and a specific increase in preference for fat in rats receiving macronutrient diets. Animals showing a preference for a fat-rich diet exhibit higher levels of GAL in the MPOA as well as the PVN and median eminence and also of NPY specifically in the MPOA. These peptides in the MPOA are similarly enhanced in animals with greater body fat, independent of diet. This evidence suggests that in the female rat, both GAL and NPY in the MPOA may contribute to the overeating and increased weight gain that occur during a fat-rich diet.

A cadaveric and clinical evaluation of endoscopically assisted zygomatic fracture repair

An endoscopic method of malar arch repair without a bicoronal incision has been recently described. To determine the effectiveness of this new technique, a cadaver study was performed to evaluate the capacity of this technique to (1) restore the anatomic position of a fractured malar arch, (2) rigidly fixate the arch, and (3) avoid injury to the frontal branch of the facial nerve. The technique of endoscopically assisted fracture repair was then applied to a clinical series of consecutive patients presenting with displaced zygomatic fractures with comminution at the malar arch. All cadaveric specimens repaired with this endoscopic technique demonstrated anatomic reduction and rigid fixation of the arch without disruption of the frontal branch of the facial nerve. In all clinical cases, four-point rigid plate fixation (zygomaticofrontal, infraorbital, malar arch, and zygomaticomaxillary buttress) was achieved endoscopically with limited access incisions. All clinical cases demonstrated excellent skeletal restoration of the zygoma on postoperative computed tomography scans. On clinical examination, facial symmetry and normal facial nerve function were observed in all patients after operation.

Galanin-containing neurons in the paraventricular nucleus: a neurochemical marker for fat ingestion and body weight gain

The physiological function of the peptide galanin (Gal) remains to be established. It is known to exist in high concentrations within the hypothalamus and to modulate the secretion of specific hormones, as well as to potentiate food consumption. Our study provides evidence for an essential function of neuronal Gal, within a specific hypothalamic area, in stimulating the behavioral process of fat ingestion and body weight gain. Through analyses of peptide levels via RIA and of gene expression via in situ hybridization, a close positive association is established between Gal in the paraventricular nucleus (PVN), particularly its midlateral region, and fat ingestion. No such relationship is detected for Gal in other brain areas or between PVN Gal and ingestion of carbohydrate or protein, supporting the behavioral and anatomical specificity of this relationship. Through PVN injection studies with antisense oligonucleotides to Gal mRNA, a dramatic decline in fat ingestion and body weight suggests that endogenous Gal contributes to the natural appetite for fat. Thus, Gal in the PVN is identified as a neurochemical marker for fat ingestion and, consequently, body weight gain.

Hypothalamic neuropeptide Y and its gene expression: relation to light/dark cycle and circulating corticosterone

The hypothalamic neuropeptide Y (NPY) system, along with levels of circulating corticosterone (CORT), were examined in rats at different times across the light/dark cycle. Tissue samples were taken from the mediobasal hypothalamus (MBH), which contains the primary hypothalamic NPY cell group of the arcuate nucleus (ARC), and the mediodorsal (MDH) hypothalamus, which contains the paraventricular and dorsomedial nuclei that receive a dense NPY innervation from the ARC. In these dissections, measurements of NPY mRNA and peptide levels were taken using a solution hybridization/nuclease protection assay procedure and radioimmunoassay. The results demonstrate that (i) NPY mRNA levels in the MBH, but not MDH, vary significantly in relation to the light/dark cycle, showing a sharp rise 4-6 h before dark onset, sustained high levels over the next 3-4 h and then, a sharp decline 1 h before dark onset; (ii) this rise in NPY mRNA in the MBH before dark onset, while associated with stable levels of MBH NPY during this time, is followed 2-4 h later, around dark onset, by a rise in NPY peptide levels of the MDH simultaneous to a decrease in NPY levels of the MBH; (iii) levels of circulating CORT shift dramatically across the light-dark cycle, exhibiting an increase from basal levels (< 0.3 microgram/dl) to 5 micrograms/dl approximately 4 h before dark onset, a further rise that peaks at 26 micrograms/dl around dark onset, and then a significant decline to 16 micrograms/dl at 2 h after dark onset; and (iv) there exists a positive relationship between CORT and NPY mRNA or peptide levels in the MBH during the 4-6 h before dark onset, while in the MDH, a positive relationship between this steroid and NPY peptide levels is obtained at dark onset. It is proposed that these rhythms, involving a predark rise in CORT and NPY gene expression leading to a peak in CORT and peptide levels at dark onset, are active in stimulating feeding behavior, particularly carbohydrate ingestion, which predominates at that time.

Specific inhibition of endogenous neuropeptide Y synthesis in arcuate nucleus by antisense oligonucleotides suppresses feeding behavior and insulin secretion

Neuropeptide Y (NPY), which is synthesized in neurons of the arcuate nucleus (ARC) that project to different hypothalamic nuclei, is known to have potent effects on eating behavior and hormone secretion after hypothalamic administration. To test the hypothesis that endogenous NPY is essential for the normal expression of these responses, the present study used to unmodified antisense oligodeoxynucleotides (ODNs) to disrupt the synthesis of NPY in the ARC and to examine the impact of this disturbance on nutrient intake, as well as on circulating levels of insulin and the adrenal steroids, corticosterone and aldosterone. Brain-cannulated rats maintained on macronutrient diets were given daily, bilateral injections, over a 4-day period, of NPY antisense ODNs, sense ODNs or saline into the ARC. The NPY antisense ODNs produced a significant decline (-33% relative to sense ODNs and -40% relative to saline, P < 0.05) in NPY levels in this nucleus, without causing any direct neural damage. Peptide levels in other hypothalamic areas, namely, the paraventricular nucleus and medial preoptic nucleus, were not significantly affected. In association with this reduction in ARC NPY, the antisense-treated animals exhibited a significant decrease in feeding behavior measured during the first 90 min of the natural feeding cycle, as well as over the 24-h period. In the 90-min interval, both carbohydrate and fat intake were suppressed by 65-70% (P < 0.05, relative to both saline and sense ODNs control scores).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of serotonin and the serotonin blocker metergoline on meal patterns and macronutrient selection

Serotonin [5-hydroxytryptamine(5-HT)] in the paraventricular nucleus (PVN) of rats has a suppressive effect on feeding behavior and causes a selective decrease in carbohydrate ingestion, specifically at the onset of the natural (dark) feeding period. Studies conducted here provide further evidence for this phenomena, showing a similar dose-related decrease in carbohydrate ingestion at dark onset after PVN injection of 5-HT or of the agonists, d-norfenfluramine or fluoxetine, which act through endogenous 5-HT. To further characterize the effects of this indoleamine on the macrostructure of feeding, a computer-automated data acquisition system was used to analyze macronutrient feeding patterns in freely feeding animals maintained on the pure diets of protein, carbohydrate, and fat. Results indicate that PVN administration of 5-HT at dark onset decreases intake of the carbohydrate nutrient by decreasing meal size, feeding time, and feeding rate for this nutrient and increasing the satiating effect of carbohydrate. These effects, which occur specifically during the first meal after injection, are opposite those seen after peripheral administration of the 5-HT receptor antagonist, metergoline. This drug stimulates feeding through a selective increase in carbohydrate intake, characterized by an increase in meal size, percent composition, and feeding time for this nutrient and a decrease in the satiety ratio for carbohydrate. These results implicate the serotonergic system in the termination of carbohydrate-rich meals that are prevalent during the early hours of the natural feeding cycle.

Meal patterns and macronutrient intake after peripheral and PVN injections of the alpha 2-receptor antagonist idazoxan

Studies with idazoxan (IDA), a specific alpha 2-noradrenergic receptor antagonist, demonstrate effects on feeding behavior opposite to those observed with norepinephrine in the paraventricular nucleus (PVN) and peripheral injection of the alpha 2 agonist clonidine. Administration of IDA, both intraperitoneally (IP) and into the PVN at the onset of the nocturnal feeding cycle, caused a dose-related, selective suppression of carbohydrate intake 90 min after injection. To characterize further the impact of this antagonist on macronutrient intake, we examined in IDA-injected animals the macrostructure of feeding using computer-assisted analyses of meal patterns. Both IP and PVN administration of IDA produced a selective suppression of carbohydrate intake, primarily during the first meal of the feeding cycle. This effect occurred through significant reductions in meal size, diet composition, feeding time, and feeding rate for this nutrient. Idazoxan administration into the PVN continued to decrease carbohydrate intake in the next two meals and reduced the satiating impact of this nutrient. In contrast to this immediate change in carbohydrate intake, PVN IDA reduced protein intake after a latency of 4 h. although fat intake was suppressed only after a latency of 7 h. An increase in total meal number and a decrease in the average meal size across the 12-h dark cycle were seen after PVN IDA administration. These results, showing effects of peripheral and PVN-injected IDA on carbohydrate intake, suggest a possible physiological role of endogenous PVN alpha 2-noradrenergic receptors in modulating natural patterns of carbohydrate feeding at the onset of the dark period.

Pregnancy and discogenic disease of the spine

Low back pain is common during pregnancy and is of moderate or severe intensity in about one fourth of all pregnancies. The etiology is multifactorial but in most cases is related to the physical and physiologic changes brought about by pregnancy. For most women, the pain resolves spontaneously, although they remain at higher risk for increased LBP in future pregnancies and for the development of symptomatic disc disease in later life. Many of the common treatments for LBP are contraindicated or must be modified in this setting. Neurologically symptomatic herniated discs are rare during pregnancy, yet, when indicated, pregnant women can safely undergo surgery.

A simple method of removing residual intrathoracic air post-thoracotomy in children

A simple and effective method of aspirating residual intrathoracic air is described. This method can be used when air leaks or persistent fluid accumulations are not expected. This technique may be easily adapted for use in older children or adults when similar circumstances are present. Standard postoperative monitoring, including serial roentgenogram of the chest, should be used to verify appropriate pulmonary re-expansion.

Analysis of neuropeptide Y-induced feeding: dissociation of Y1 and Y2 receptor effects on natural meal patterns

To differentiate NPY receptor subtypes, Y1 and Y2, in terms of their impact on feeding behavior, the intact molecule NPY(1-36) and the 3 fragments, NPY(2-36), the Y1 agonist [Leu31,Pro34]NPY, and the Y2 agonist NPY(13-36), were injected (100 pmol/0.3 microliters) into the hypothalamic paraventricular nucleus (PVN) of freely feeding rats. A computer-automated data acquisition system was employed in these experiments to permit a detailed analysis of feeding over the 12-h nocturnal cycle, in animals maintained on pure macronutrient diets. The results demonstrate that: 1) NPY(1-36) potentiates feeding behavior, primarily carbohydrate ingestion, by increasing the size and duration of the first meal after injection, rather than by affecting meal number of feeding rate, suggesting that NPY acts through mechanisms of satiety. The potentiation of carbohydrate intake occurs in association with a suppression of protein intake, which is strongest during the second meal after injection and which further increases the proportion of carbohydrate in the diet. No changes in fat ingestion are seen. 2) NPY(2-36), with the N-terminal tyrosine residue deleted, is equally potent to NPY(1-36) in potentiating carbohydrate intake and increasing meal size; however, it is less selective than NPY(1-36), producing an additional, smaller increase in consumption of protein. 3) The stimulatory effect of these peptides on carbohydrate intake and meal size is similarly observed, with somewhat reduced potency, after PVN injection of the selective Y1 agonist [Leu31,Pro34]NPY which, like NPY(1-36), also reduces protein intake. 4) The Y2 receptor agonist, NPY(13-36), causes a decrease in the ingestion of carbohydrate, a smaller decline in protein intake, and a reduction in meal size. It is proposed that hypothalamic Y1 receptors mediate the stimulatory effect of NPY on carbohydrate intake and meal size, while Y2 receptors have the opposite effect of suppressing carbohydrate intake, possibly by altering presynaptic release of monoamines known to influence nutrient ingestion.

The effect of intravenous interleukin-2 on brain water content

Parenteral treatment with interleukin-2 (IL-2) is effective against certain advanced cancers outside the central nervous system. Prior to commencement of Phase II trials in patients with brain tumors, the neurological and neuroradiological features of 10 patients treated with intravenous administration of repeated doses of IL-2 were studied. Three patients had malignant gliomas, and seven patients had extracranial cancer without evidence of intracranial metastasis. All were treated with intravenous doses of 10(5) U/kg three times daily for up to 5 days. The patients with gliomas received cranial computerized axial tomography (CT) scans before IL-2 therapy was initiated and during the later stages of treatment. The patients with extracranial cancer underwent T2-weighted magnetic resonance (MR) imaging before and later during therapy. After two to 11 doses of IL-2, the patients with gliomas had marked neurological deterioration that was associated with a mild to marked increase in peritumoral edema and mass effect visible on CT scans. With cessation of treatment and appropriate supportive care, all returned to their pretreatment state. The patients with extracranial cancer were either neurologically unchanged or underwent minor transient changes in mental status (lethargy and confusion). In these patients, the MR signal intensity was quantified and compared in eight anatomic regions of interest. In six of the seven patients, there were increases in gray and white matter signal intensity consistent with increased cerebral water content. The percentage changes (means +/- standard error of the means) were 12.6% +/- 7.3% in the gray matter and 17.0% +/- 6.2% in the white matter. This study demonstrates that treatment with a high parenteral dose of IL-2 is not tolerated by patients with gliomas due to increased cerebral edema. In patients with extracranial cancer but no brain disease, parenteral IL-2 induces an increase in the cerebral water content of both gray and white matter.

The effect of interleukin-2 on the blood-brain barrier in the 9L gliosarcoma rat model

Carbon-14-labeled aminoisobutyric acid was used to determine local blood-to-tissue transfer constants in 22 Fischer rats with intracerebral 9L gliosarcomas that received either high-dose parenteral interleukin-2 (IL-2) or a control injection. In tumor and peritumoral tissue, the transfer constants in the IL-2-treated animals (89.6 +/- 14.6 and 35.8 +/- 6.0, respectively, mean +/- standard error of the mean) were larger (p less than 0.05) than in control animals (61.4 +/- 6.4 and 14.6 +/- 2.2, respectively). In contrast, in normal frontal and occipital tissue contralateral to the tumor-bearing hemisphere, there was no significant difference between the transfer constants in IL-2-treated and control animals. Furthermore, treatment of animals with IL-2 excipient caused no change in permeability as compared to animals treated with Hanks' balanced salt solution. Parenteral injection of IL-2 increases blood-brain barrier disruption in tumor-bearing rat brain but does not increase the vascular permeability of normal brain. Methods to prevent this increased tumor vessel permeability are required before parenteral IL-2 can be used safely for the treatment of primary or metastatic brain tumors.

The design and use of a simple device for rapid quench-freezing of biological samples

The detailed design of a simple device for rapid quench-freezing of biological samples under reproducible conditions is presented. With spring-augmented descent, sample immersion velocity of 10 m s-1 into a cryogenic liquid is achieved. Biological samples, loaded in Balzers planchets, Denton holders, or a newly designed 'titanium envelope', are suitable for rapid-freezing with this device. Using 4 micrometers titanium foil, light weight (1 mg) streamlined holders can easily be made to enclose cell suspensions or tissue samples. The foil envelope is designed for efficient heat dissipation while protecting the sample from possible impact or flow distortions occurring from spring-augmented immersion. Human erythrocytes, quench-frozen in the titanium envelope, were prepared for electron microscopy by the freeze-substitution technique. Two opposing 25--30 micrometers surface zones were frozen in the apparent absence of ice. The extended depth of cryofixation is attributed to the advantages of thin foil in the titanium envelope design and the use of rapid-immersion technique.

Myasthenia in frogs immunized against cholinergic-receptor protein

Frogs immunized with cholinergic-receptor protein developed myasthenia in 116--175 days. The muscular weakness was overcome by subcutaneous administration of 20 microgram of neostigmine. Electromyograms showed a decline in action potential amplitude during a 2-Hz train. Nerve stimulation evoked subthreshold end-plate potentials (EPPs) averaging 10.4 +/- 7.4 mV, but at many junctions no EPP was obtained. Miniature EPP amplitude had a modal value of 0.15 mV compared with 0.35 mV for the controls. The corresponding means were 0.24 +/- 0.23 mV and 0.48 +/- 0.23 mV. Microperfusion with edrophonium (5 mg/l) increased the amplitude of EPPs and miniature end-plate potentials (MEPPS). Postjunctional response tested with 20 muM carbamylcholine was 56% of control. Postjunctional response by carbamylcholine iontophoresis gave 19 +/- 22 mV/nC compared with 76 +/- 50 mV/nC for the controls. The data indicate that the neuromuscular transmission deficits in receptor-immunized frogs are mainly postsynaptic in origin, but there may be additional presynaptic contributions. This amphibian model of myasthenia gravis offers many opportunities and advantages in the study of receptor-immunized animals.

Dipping cone to correct optical distortions at liquid surfaces

A dipping cone attachment for use with a long-working-distance objective is described. The device eliminates degradation of the microscope image which occurs when microelectrodes are applied to single muscle fibers in vitro.