Synaptopodin is required for long-term depression at Schaffer collateral-CA1 synapses

Synaptopodin (SP), an actin-associated protein found in telencephalic neurons, affects activity-dependant synaptic plasticity and dynamic changes of dendritic spines. While being required for long-term depression (LTD) mediated by metabotropic glutamate receptor (mGluR-LTD), little is known about its role in other forms of LTD induced by low frequency stimulation (LFS-LTD) or spike-timing dependent plasticity (STDP). Using electrophysiology in ex vivo hippocampal slices from SP-deficient mice (SPKO), we show that absence of SP is associated with a deficit of LTD at Sc-CA1 synapses induced by LFS-LTD and STDP. As LTD is known to require AMPA- receptors internalization and IP3-receptors calcium signaling, we tested by western blotting and immunochemistry if there were changes in their expression which we found to be reduced. While we were not able to induce LTD, long-term potentiation (LTP), albeit diminished in SPKO, can be recovered by using a stronger stimulation protocol. In SPKO we found no differences in NMDAR, which are the primary site of calcium signalling to induce LTP. Our study shows, for the first time, the key role of the requirement of SP to allow induction of activity-dependant LTD at Sc-CA1 synapses.

Loss of synaptopodin impairs mGluR5 and protein synthesis-dependent mGluR-LTD at CA3-CA1 synapses

Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) is an important form of synaptic plasticity that occurs in many regions of the central nervous system and is the underlying mechanism for several learning paradigms. In the hippocampus, mGluR-LTD is manifested by the weakening of synaptic transmission and elimination of dendritic spines. Interestingly, not all spines respond or undergo plasticity equally in response to mGluR-LTD. A subset of dendritic spines containing synaptopodin (SP), an actin-associated protein is critical for mGluR-LTD and protects spines from elimination through mGluR1 activity. The precise cellular function of SP is still enigmatic and it is still unclear how SP contributes to the functional aspect of mGluR-LTD despite its modulation of the structural plasticity. In this study, we show that the lack of SP impairs mGluR-LTD by negatively affecting the mGluR5-dependent activity. Such impairment of mGluR5 activity is accompanied by a significant decrease of surface mGluR5 level in SP knockout (SPKO) mice. Intriguingly, the remaining mGluR-LTD becomes a protein synthesis-independent process in the SPKO and is mediated instead by endocannabinoid signaling. These data indicate that the postsynaptic protein SP can regulate the locus of expression of mGluR-LTD and provide insight into our understanding of spine/synapse-specific plasticity.

Loss of synaptopodin impairs mGluR5 and protein synthesis dependent mGluR-LTD at CA3-CA1 synapses

Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) is an important form of synaptic plasticity that occurs in many regions of the CNS and is the underlying mechanism for several learning paradigms. In the hippocampus, mGluR-LTD is manifested by the weakening of synaptic transmission and elimination of dendritic spines. Interestingly, not all spines respond or undergo plasticity equally in response to mGluR-LTD. A subset of dendritic spines containing synaptopodin (SP), an actin-associated protein, are critical for mGluR-LTD and protect spines from elimination through mGluR1 activity. The precise cellular function of SP is still enigmatic and it is still unclear how SP contributes to the functional aspect of mGluR-LTD despite of its modulation on the structural plasticity. In the present study, we show that the lack of SP impairs mGluR-LTD by negatively affecting the mGluR5-dependent activity. Such impairment of mGluR5 activity is accompanied by a significant decrease of surface mGluR5 level in SP knockout (SPKO) mice. Intriguingly, the remaining mGluR-LTD becomes a protein synthesis-independent process in the SPKO and is mediated instead by endocannabinoid signaling. These data show for the first time that the postsynaptic protein SP can regulate the locus of expression of mGluR-LTD and provide insight to our understanding of spine/synapse-specific plasticity.

Significance statement

Hippocampal group I metabotropic glutamate receptor dependent long-term depression (mGluR-LTD), a form of learning and memory, is misregulated in many murine models of neurodevelopmental disorders. Despite extensive studies there is a paucity of information on the molecular mechanism underlying mGluR-LTD. Previously, we reported that loss of synaptopodin, an actin-associated protein found in a subset of mature dendritic spines, impairs mGluR-LTD. In the current study, we uncover the molecular and cellular deficits involved. We find that synaptopodin is required for the mGluR5-Homer interaction and uncover synaptopodin as a molecular switch for mGluR-LTD expression, as mGluR-LTD becomes protein synthesis-independent and relies on endocannabinoid signaling in synaptopodin knock-out. This work provides insight into synaptopodin as a gatekeeper to regulate mGluR-LTD at hippocampal synapses.

[Efficacy and safety of neoadjuvant chemotherapy combined with PD-1 antibody for esophageal squamous cell carcinoma in the real world]

Objective: To evaluate the efficacy and safety of neoadjuvant chemotherapy combined with programmed death-1 (PD-1) antibody in operable, borderline or potentially resectable locally advanced esophageal squamous cell carcinoma(ESCC) in the real world. Methods: The study retrospectively analyzed 28 patients with operable or potentially resectable locally advanced ESCC patients treated with preoperative chemotherapy combined with PD-1 inhibitor in Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School from April 2020 to March 2021. According to the clinical TNM staging system of the 8th edition of the American Joint Committee on Cancer, there were 1, 15, 10, 1 and 1 case of stage Ⅱ, Ⅲ, ⅣA, ⅣB and unknown stage respectively. The treatment was two cycle of dual drug chemotherapy regimen including taxane plus platinum or fluorouracil combined with PD-1 antibody followed by tumor response assessment and surgery if the patient was eligible for resection. Results: Of the 28 patients, 1, 2, 3 and 4 cycles of chemotherapy combined with PD-1 antibody treatment completed in 1, 21, 5, and 1 patient, respectively. Objective response rate (ORR) was 71.4% (20/28), and disease control rate (DCR) was 100% (28/28). The incidence of adverse events exceeding grade 3 levels was 21.4% (6/28), including 3 neutropenia, 1 leukopenia, 1 thrombocytopenia and 1 immune hepatitis. There was no treatment-related death. Of the 23 patients underwent surgery, R0 resection rate was 87.0% (20/23), 13 patients had down staged to the T1-2N0M0 I stage, the pCR rate was 17.3% (4/23), and the pCR rate of primary tumor was 21.7% (5/23). Four patients received definitive chemoradiotherapy. One patient rejected surgery and other treatment after achieved PR response. Conclusion: Neoadjuvant chemotherapy combined PD-1 inhibitor is safe and has high efficacy in operable, borderline or potentially resectable locally advanced ESCC, and it is a promising regimen.

Sulfated Hyperbranched and Linear Polyglycerols Modulate HMGB1 and Morphological Plasticity in Neural Cells

The objective of this study was to establish if polyglycerols with sulfate or sialic acid functional groups interact with high mobility group box 1 (HMGB1), and if so, which polyglycerol could prevent loss of morphological plasticity in excitatory neurons in the hippocampus. Considering that HMGB1 binds to heparan sulfate and that heparan sulfate has structural similarities with dendritic polyglycerol sulfates (dPGS), we performed the experiments to show if polyglycerols can mimic heparin functions by addressing the following questions: (1) do dendritic and linear polyglycerols interact with the alarmin molecule HMGB1? (2) Does dPGS interaction with HMGB1 influence the redox status of HMGB1? (3) Can dPGS prevent the loss of dendritic spines in organotypic cultures challenged with lipopolysaccharide (LPS)? LPS plays a critical role in infections with Gram-negative bacteria and is commonly used to test candidate therapeutic agents for inflammation and endotoxemia. Pathologically high LPS concentrations and other stressful stimuli cause HMGB1 release and post-translational modifications. We hypothesized that (i) electrostatic interactions of hyperbranched and linear polysulfated polyglycerols with HMGB1 will likely involve sites similar to those of heparan sulfate. (ii) dPGS can normalize HMGB1 compartmentalization in microglia exposed to LPS and prevent dendritic spine loss in the excitatory hippocampal neurons. We performed immunocytochemistry and biochemical analyses combined with confocal microscopy to determine cellular and extracellular locations of HMGB1 and morphological plasticity. Our results suggest that dPGS interacts with HMGB1 similarly to heparan sulfate. Hyperbranched dPGS and linear sulfated polymers prevent dendritic spine loss in hippocampal excitatory neurons. MS/MS analyses reveal that dPGS-HMGB1 interactions result in fully oxidized HMGB1 at critical cysteine residues (Cys23, Cys45, and Cys106). Triply oxidized HMGB1 leads to the loss of its pro-inflammatory action and could participate in dPGS-mediated spine loss prevention. LPG-Sia exposure to HMGB1 results in the oxidation of Cys23 and Cys106 but does not normalize spine density.

Novel ADNP Syndrome Mice Reveal Dramatic Sex-Specific Peripheral Gene Expression With Brain Synaptic and Tau Pathologies

BACKGROUND

ADNP is essential for embryonic development. As such, de novo ADNP mutations lead to an intractable autism/intellectual disability syndrome requiring investigation.

METHODS

Mimicking humans, CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 editing produced mice carrying heterozygous Adnp p.Tyr718∗ (Tyr), a paralog of the most common ADNP syndrome mutation. Phenotypic rescue was validated by treatment with the microtubule/autophagy-protective ADNP fragment NAPVSIPQ (NAP).

RESULTS

RNA sequencing of spleens, representing a peripheral biomarker source, revealed Tyr-specific sex differences (e.g., cell cycle), accentuated in females (with significant effects on antigen processing and cellular senescence) and corrected by NAP. Differentially expressed, NAP-correctable transcripts, including the autophagy and microbiome resilience-linked FOXO3, were also deregulated in human patient-derived ADNP-mutated lymphoblastoid cells. There were also Tyr sex-specific microbiota signatures. Phenotypically, Tyr mice, similar to patients with ADNP syndrome, exhibited delayed development coupled with sex-dependent gait defects. Speech acquisition delays paralleled sex-specific mouse syntax abnormalities. Anatomically, dendritic spine densities/morphologies were decreased with NAP amelioration. These findings were replicated in the Adnp^+/- mouse, including Foxo3 deregulation, required for dendritic spine formation. Grooming duration and nociception threshold (autistic traits) were significantly affected only in males. Early-onset tauopathy was accentuated in males (hippocampus and visual cortex), mimicking humans, and was paralleled by impaired visual evoked potentials and correction by acute NAP treatment.

CONCLUSIONS

Tyr mice model ADNP syndrome pathology. The newly discovered ADNP/NAP target FOXO3 controls the autophagy initiator LC3 (microtubule-associated protein 1 light chain 3), with known ADNP binding to LC3 augmented by NAP, protecting against tauopathy. NAP amelioration attests to specificity, with potential for drug development targeting accessible biomarkers.

Cross-talk between GABAergic postsynapse and microglia regulate synapse loss after brain ischemia

Microglia interact with neurons to facilitate synapse plasticity; however, signal(s) contributing to microglia activation for synapse elimination in pathology are not fully understood. Here, using in vitro organotypic hippocampal slice cultures and transient middle cerebral artery occlusion (MCAO) in genetically engineered mice in vivo, we report that at 24 hours after ischemia, microglia release brain-derived neurotrophic factor (BDNF) to downregulate glutamatergic and GABAergic synapses within the peri-infarct area. Analysis of the cornu ammonis 1 (CA1) in vitro shows that proBDNF and mBDNF downregulate glutamatergic dendritic spines and gephyrin scaffold stability through p75 neurotrophin receptor (p75^NTR) and tropomyosin receptor kinase B (TrkB) receptors, respectively. After MCAO, we report that in the peri-infarct area and in the corresponding contralateral hemisphere, similar neuroplasticity occurs through microglia activation and gephyrin phosphorylation at serine-268 and serine-270 in vivo. Targeted deletion of the Bdnf gene in microglia or GphnS268A/S270A (phospho-null) point mutations protects against ischemic brain damage, neuroinflammation, and synapse downregulation after MCAO.

Structure-activity relationship (SAR) studies of synthetic glycogen synthase kinase-3β inhibitors: A critical review

Glycogen Synthase Kinase-3 (GSK-3) is a constitutively dynamic, omnipresent serine/threonine protein kinase regularly called as a "multitasking kinase" due to its pliable function in diverse signaling pathways. It exists in two isoforms i.e., GSK-3α and GSK-3β. Inhibition of GSK-3 may be useful in curing various diseases such as Alzheimer's disease, type II diabetes, mood disorders, cancers, chronic inflammatory agents, stroke, bipolar disorders and so on, but the approach poses significant challenges. Lithium was the first GSK-3β inhibitor to be used for therapeutic outcome and has been effectively used for many years. In recent years, a large number of structurally diverse potent GSK-3β inhibitors are reported. The present review focuses on the recent developments in the area of medicinal chemistry to explore the diverse chemical structures of potent GSK-3β inhibitors and also describes its structure-activity relationships (SAR) and molecular binding interactions of favorable applicability in various diseases.

Growth of preterm infants fed nutrient-enriched or term formula after hospital discharge

OBJECTIVE

At hospital discharge, preterm infants may have low body stores of nutrients, deficient bone mineralization, and an accumulated energy deficit. This double-blind, randomized study evaluated the growth of premature infants with birth weights <1800 g who were fed a 22 kcal/fl oz nutrient-enriched postdischarge formula (PDF) or a 20 kcal/fl oz term-infant formula (TF) from hospital discharge to 12 months' corrected age (CA).

METHODS

Infants were randomized to PDF or TF a few days before hospital discharge with stratification by gender and birth weight (<1250 g or >/=1250 g). The formulas were fed to 12 months' CA. Growth was evaluated using analysis of variance controlling for site, feeding, gender, and birth weight group. Interaction effects were also assessed. Secondary analyses included a repeated measures analysis and growth modeling.

RESULTS

One hundred twenty-five infants were randomized; 74 completed to 6 months' CA and 53 to 12 months' CA. PDF-fed infants weighed more than TF-fed infants at 1 and 2 months' CA, gained more weight from study day 1 to 1 and 2 months' CA, and were longer at 3 months' CA. There were significant interactions between feeding and birth weight group-among infants with birth weights <1250 g, those fed PDF weighed more at 6 months' CA, were longer at 6 months' CA, had larger head circumferences at term 1, 3, 6, and 12 months' CA, and gained more in head circumference from study day 1 to term and to 1 month CA. The repeated measures and growth modeling analyses confirmed the analysis of variance results. The PDF formula seemed to be of particular benefit for the growth of male infants. Infants fed the PDF consumed less formula and had higher protein intakes at several time points. Energy intakes, however, were not different.

CONCLUSIONS

Growth was improved in preterm infants fed a nutrient-enriched postdischarge formula after hospital discharge to 12 months' CA. Beneficial effects were most evident among infants with birth weights <1250 g, particularly for head circumference measurements.

Enhanced antitumor immunity by fusion of CTLA-4 to a self tumor antigen

The idiotypic determinant (Id) of the immunoglobulin expressed by a B-cell malignancy can serve as an effective tumor-specific antigen but is only weakly immunogenic. This study demonstrates that the immunogenicity of the tumor Id protein can be dramatically increased by directing it to antigen-presenting cells (APCs). Cytotoxic T-lymphocyte antigen 4 (CTLA-4) present on activated T cells has a strong binding affinity to both B7-1 and B7-2 molecules, which are primarily expressed on APCs. After construction of a fusion protein consisting of Id and CTLA-4 (Id-CTLA4), mice immunized with the fusion protein induced high titers of Id-specific antibody and T-cell proliferative responses without adjuvants and were protected from lethal tumor challenge. The Id-CTLA4 fusion protein was so potent that even low doses (down to 0.1 microg) of the immunogen were able to elicit strong antibody responses. By using an Id-CTLA4 mutant protein, the ability to bind B7 molecules on APCs was shown to be required for the enhanced immunogenicity of Id-CTLA4. These findings demonstrate that fusing CTLA-4 to a potential tumor antigen represents an effective approach to prime antitumor immunities in vivo and may be applicable to the design of vaccines for a variety of other diseases. (Blood. 2000;96:3663-3670)

Accelerated clearance of polyethylene glycol-modified proteins by anti-polyethylene glycol IgM

Tumor therapy by the preferential activation of a prodrug at tumor cells targeted with an antibody-enzyme conjugate may allow improved treatment efficacy with reduced side effects. We examined antibody-mediated clearance of poly(ethylene glycol)-modified beta-glucuronidase (betaG-sPEG) as a method to reduce serum concentrations of enzyme and minimize systemic prodrug activation. Enzyme-linked immunosorbent assay and immunoblot analysis of two monoclonal antibodies generated by immunization of BALB/c mice with an antibody-betaG-sPEG conjugate showed that mAb 1E8 (IgG1) bound betaG and betaG-sPEG whereas mAb AGP3 (IgM) bound poly(ethylene glycol). Neither antibody affected the betaG activity. mAb 1E8 and AGP3 were modified with 36 and 208 galactose residues (1E8-36G and AGP3-208G) with retention of 72 and 48% antigen-binding activity, respectively, to target immune complexes to the asialoglycoprotein receptor on liver cells. mAb 1E8 and AGP3 cleared betaG-PEG from the circulation of mice as effectively as 1E8-36G and AGP3-208G, respectively. mAb AGP3, however, cleared betaG-sPEG more completely and rapidly than 1E8, reducing the serum concentration of betaG-sPEG by 38-fold in 8 h. AGP3 also reduced the concentration of an antibody-betaG-sPEG conjugate in blood by 280-fold in 2 h and 940-fold in 24 h. AGP3-mediated clearance did not produce obvious damage to liver, spleen, or kidney tissues. In addition, AGP3 clearance of betaG-sPEG before administration of BHAMG, a glucuronide prodrug of p-hydroxyaniline mustard, prevented toxicity associated with systemic activation of the prodrug based on mouse weight and blood cell numbers. AGP3 should be generally useful for accelerating the clearance of PEG-modified proteins as well as for improving the tumor/blood ratios of antibody-betaG-PEG conjugates for glucuronide prodrug therapy of cancer.

Glutamine supplementation for low-birth-weight and very low-birth-weight infants

Glutamine is a conditionally essential amino acid for low-birth-weight (LBW) and very low-birth-weight (VLBW) infants by virtue of its ability to serve as a primary respiratory fuel for proliferating cells, a carrier of nitrogen between tissues, maintain acid-base balance, promote the growth and integrity of the gastrointestinal tract and promote immunologic responses. While adults can synthesize glutamine in the muscles and brain to meet essential requirements under normal state of health, the LBW and VLBW infants may not be able to do so since the enzymes (glutamine synthetase and glutaminase) activities are low. In addition, these infants are under stress due to conditions like the respiratory distress syndrome, acid-base imbalances, infections, and inadequate immunologic responses. Current amino acid mixtures and formula preparations are inadequate to meet the needs of these infants for this amino acid. Thus supplementation of parenteral and enteral nutrition with glutamine would be beneficial.

The management of patients with advanced motor neuron disease

BACKGROUND

There is no specific treatment for motor neuron disease (MND) except hospice or palliative care to improve patients' quality of life and decrease complications. This topic is seldom discussed in Taiwan.

METHODS

A retrospective study was conducted of patients with terminal MND who were treated and died at the Veterans General Hospital-Taipei from March 1986 through April 1996. Patients' characteristics, management, length of survival and cause of death were analyzed.

RESULTS

Twenty-three patients (M/F, 17/6) were included. The median age of onset was 59 years (range, 24-69). The median interval from onset of symptoms to diagnosis was nine months (range, 2-36). Seventeen patients received mechanical ventilation for an average median of six months. Nineteen patients had dysphagia, 17 received long-term nasogastric tube feeding, one had gastrostomy and one was treated with cricopharyngeal myotomy. Pain over the neck, trunk or limbs was reported by 18 patients; none received narcotics. Only two patients received respiratory exercise training and two had a cervical collar for stabilization. Electronic communication aids were not available. The median survival from onset of symptoms was 36 months (range, 7-99). The causes of death included sepsis (n = 13), respiratory failure (n = 7), heart disease (n = 2) and MND-related cachexia (n = 1). Cardiopulmonary resuscitation was performed for 12 patients.

CONCLUSIONS

In Taiwan, management of patients with advanced MND is mainly hospital-based and most of the effort is focused on life-sustaining. More attention needs to be paid to improvement of the quality of life and dignity of the patient.

Poly(ethylene glycol) modification of beta-glucuronidase-antibody conjugates for solid-tumor therapy by targeted activation of glucuronide prodrugs

Methoxypoly(ethylene glycol) (PEG) modification of Escherichia coli beta-glucuronidase (betaG) was examined as a method to improve the stability and pharmacokinetics of antibody-betaG conjugates for the targeted activation of glucuronide prodrugs at tumor cells. Introduction of 3 PEG molecules did not affect betaG activity whereas higher degrees of PEG modification produced progressively greater loss of enzymatic activity. The enzyme was found to be stable in serum regardless of PEG modification. PEG-modified betaG was coupled via a thioether bond to mAb RH1, an IgG2a antibody that binds to the surface of AS-30D hepatoma cells, to produce conjugates with 3 (RH1-betaG-3PEG), 5.2 (RH1-betaG-5PEG) or 9.8 (RH1-betaG-10PEG) PEG molecules per betaG with retention of 75%, 45% and 40% of the combined antigen-binding and enzymatic activity of the unmodified conjugate RH1-betaG. In contrast to the rapid serum clearance of RH1-betaG observed in mice, the PEG-modified conjugates displayed extended serum half-lives. RH1-betaG-3PEG and RH1-betaG-5PEG also exhibited reduced spleen uptake and greater tumor accumulation than RH1-betaG. BHAMG, the glucuronide prodrug of p-hydroxyaniline mustard (pHAM), was relatively nontoxic in vivo. Injection of 6 mg/kg or 12 mg/kg pHAM i.v. depressed white blood cell numbers by 46% and 71% whereas 80 mg/kg BHAMG reduced these levels by 22%. Although the tumor/blood ratio of RH1-betaG-5PEG was adversely affected by slow clearance from serum, combined therapy of small solid hepatoma tumors with this conjugate, followed 4 and 5 days later with i.v. injections of BHAMG, cured all of seven mice with severe combined immunodeficiency. Combined treatment with a control antibody-betaG conjugate and BHAMG delayed tumor growth and cured two of six mice while treatment with pHAM or BHAMG alone was ineffective.

Infant of diabetic mother: a continuing challenge for perinatal-neonatal medicine

Current increase in the incidence of diabetes mellitus complicating pregnancy is of concern since it is associated with an increase in mortality and morbidity of the fetus and neonate. Pregnancy itself is diabetogenic caused by increased insulin resistance due to the production of hormones like estrogen, progesterone, cortisol, human chorionic somatomammotropin (hCS) and human placental lactogen (hPL). The latter increases lypolysis which provides free fatty acids and ketones as fuels for energy for the pregnant mother. This spares maternal blood glucose, amino acids and ketones which cross the placenta to the fetus. The influx of nutrients increases fetal insulin production which together with hPL induce somatogenesis. Maternal hyperglycemia and fetal hypoxemia are shown to be responsible for structural congenital anomalies of the rapidly developing organs of the fetus during the early weeks of gestation while continuing hyperglycemia and hypoxemia in the second and third trimester are factors related to the production of macrosomia, including cardiomyopathy, delay in lung maturation, and polycythemia. Metabolic problems such as hypoglycemia, hypocalcemia, hypomagnesemia and hyperbilirubinemia are common neonatal morbidities. Follow-up of the infants of diabetic mothers indicates that these infants have a 20 fold increase in acquiring diabetes. Early identification of maternal diabetes with strict metabolic control prior to conception as well as throughout pregnancy together with careful fetal monitoring can reduce the incidence of congenital anomalies and morbidities in the fetus and neonate.

Effects of the callipyge phenotype on serum creatinine, total cholesterol, low-density lipoproteins, very-low-density lipoproteins, high-density lipoproteins, and triacylglycerol in growing lambs

The goals of this study were to investigate the effects of the callipyge (CLPG) phenotype on serum creatinine and lipid profiles of growing lambs. Preliminary studies in our laboratories indicated that creatinine may have utility in distinguishing the CLPG phenotype and that expression of the CLPG gene altered concentrations of serum total cholesterol (TC). As a result, in this study, we examined the influence of the CLPG gene on concentrations of creatinine, TC, very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triacylglycerol (TG) at varying stages of maturity in lambs. Ten homozygous (c/c) Polypay ewes were crossed with Dorset rams heterozygous for the CLPG gene (C/c). From this cross, 20 lambs (13 females and 7 males) were born, of which 11 were homozygotic (c/c) and 9 were heterozygotic (C/c; CLPG) based on muscle weights and longissimus dorsi (LD) area at slaughter. Blood samples were taken at monthly intervals and serum lipid constituents were assayed. At 1 mo of age, no differences (P > .05) in plasma lipids were detectable between phenotypes. However, at 2 mo age, CLPG lambs had higher (P < .01) concentration of TG, TC, HDL, and VLDL compared to homozygotic (c/c) lambs. Triglycerides and VLDL were elevated (P < .05) in CLPG lambs at 3 mo of age. By slaughter, no differences (P > .05) in serum lipid constituents were detectable between genotypes. Hence, the increase in serum TC is due to elevated levels of HDL and VLDL. These observations indicate that creatinine may be used to distinguish CLPG lambs and that the CLPG gene alters serum lipid profiles during the postnatal period.

[Ultrasonography of hips in neonates]

For evaluation of the development of the hip joints in young infants, between Jun., 1988 and Oct., 1991, 522 hips of the infants under 4 months of age were studied by ultrasonography based on the method well described by Graf. The results revealed only 48% of the hips of neonatal group was type I (stable type). But this percentage increased with age: 90% in the group under 2 months of age; 97% in the group under 4 months of age. Compared with the findings of other studies in Europe, the development and the stability of the hips of our neonatal group seemed poorer. But this condition improved much within 2 months after birth. So we concluded that, except the high risk group, the ultrasonographic screening approach should be performed after 2 months of age, but not in neonatal period under considering the cost-benefit.

Use of fetal ultrasound to select metabolic therapy for pregnancies complicated by mild gestational diabetes

OBJECTIVE

To determine whether fetal ultrasound early in the third trimester can identify Latina with mild gestational diabetes mellitus (GDM) whose fetuses are at risk for macrosomia and, if so, whether maternal insulin therapy can reduce that risk.

RESEARCH DESIGN AND METHODS

Study subjects included 303 consecutive women with GDM and a fasting serum glucose level < 5.8 mM on diet therapy who had a fetal ultrasound between 29 and 33 weeks gestation. Of the women, 98 (32%) had a fetal AC > or = 75th percentile for gestational age, and 59 women completed a randomized trial of diet therapy (n = 29) or diet plus twice daily insulin (n = 30). Maternal nutrient levels were assessed by meal tolerance testing (MTT) before and during therapy and by capillary glucose monitoring four to seven times a day. Birth weights corrected for gestational age and neonatal glycemia and skin folds were the primary outcome variables compared between treatment groups.

RESULTS

Diet and diet-plus-insulin groups were well matched for maternal age, prepregnancy relative weight, weight gain during pregnancy, and glycemia at entry. Insulin therapy reduced maternal capillary (P < 0.005) and MTT (P < 0.001) glucose levels and prevented a diet-associated rise in MTT triglyceride levels (P < 0.002). Gestational age at delivery was similar in insulin- and diet-treated groups (39.6 +/- 0.2 vs. 39.5 +/- 0.2 weeks). Birth weights (3,647 +/- 67 vs. 3,878 +/- 84 g; P < 0.02), the prevalence of large-for-gestational age infants (13 vs. 45%, P < 0.02), and neonatal skin-fold measurements at three sites (P < 0.005) were reduced in the insulin-treated group. Rates of transient neonatal hypoglycemia were low in both treatment groups (14 and 18%, respectively) and did not differ significantly between groups.

CONCLUSIONS

Fetal ultrasound early in the third trimester identified women with mild GDM whose infants were at high risk for fetal macrosomia in the absence of standard glycemic criteria for insulin therapy. Insulin treatment reduced the macrosomia, indicating that fetal ultrasound can be used to guide metabolic therapy in pregnancies complicated by mild GDM.

Testing for drugs of abuse in meconium of newborn infants

A reliable and sensitive screening procedure has been developed for drugs of abuse (amphetamines, cocaine metabolites, opiates, and phencyclidine [PCP]) in meconium from infants. The substances in meconium were extracted with chloroform-isopropanol (3:1) and screened by enzyme multiplied immunoassay technique (EMIT). The lower detection limits of the EMIT for benzoylecgonine, d-methamphetamine, morphine, and PCP were 250 ng/g, 730 ng/g, 110 ng/g, and 100 ng/g, respectively. This method was applied to meconium from 50 infants born to mothers suspected of using the drugs of abuse during pregnancy. Of the 50, 12 were positive for benzoylecgonine, seven for opiates, and one for PCP. The presence of benzoylecgonine and PCP in meconium was confirmed by gas chromatography/mass spectrometry and that of opiates by thin-layer chromatography. The routine analysis of meconium for drugs of abuse is recommended in cases where (A) urine can not be obtained or (B) urinalysis is negative for the substances despite a strong suspicion of maternal use of the substances during pregnancy.

Gastrointestinal tolerance, fat absorption, plasma ketone and urinary dicarboxylic acid levels in low-birth-weight infants fed different amounts of medium-chain triglycerides in formula

This study was conducted to evaluate the effect of medium-chain triglycerides (MCT) in a formula for low-birth-weight (LBW) infants on gastrointestinal tolerance, fat absorption, plasma ketone levels, and urinary dicarboxylic acid (DCA) excretion. At the start of enteral feedings, 64 LBW infants (< or = 1500 g) were randomly assigned to one of four experimental formulas. The formulas contained either 0, 17, 34, or 50% of the total fat as MCT oil. The nonfat constituents of all four formulas were the same and identical to Similac Special Care 24 (SCF). Infants were studied from the start of enteral feeding until approximately 7 days after reaching full feeds. Growth and tolerance were assessed in all infants over the entire feeding period. A 48-h balance study was conducted after enteral intake exceeded 100 kcal/kg/day for 3 days. Stool fat, plasma D-(-)-3-hydroxybutyrate (3HB) and carnitine, serum glucose, and urinary DCA levels were determined. Groups did not differ in growth, formula intake, fat absorption (76-84%), serum glucose, or plasma carnitine levels. Gastrointestinal tolerance was excellent and did not differ among groups. Plasma 3HB was significantly different (p < 0.05) only between the 0 and 50% MCT groups, 50 +/- 10 versus 120 +/- 20 microM, respectively. The excretion of urinary DCAs increased with increasing amounts of MCT in the formula. In conclusion, fat absorption and gastrointestinal tolerance were not affected by different MCT levels (0 to 50% of the total fat), but higher levels of plasma 3HB and urinary DCAs were associated with higher levels of MCT in the LBW formulas studied.

A comparison of rat brain amino acid and monoamine content in diazepam withdrawal and after exposure to a phobic stimulus

1. The content of amino acids (taurine, glycine, glutamic acid, gamma-aminobutyric acid (GABA) and aspartic acid) and monoamines (5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and noradrenaline) in homogenates of rat cortical and hippocampal tissue were measured by high performance liquid chromatography (h.p.l.c.) with fluorescent and electrochemical detection respectively, after two anxiogenic treatments: exposure to a phobic stimulus (cat odour) and withdrawal from chronic diazepam treatment. 2. In neither of the two anxiogenic situations was there a significant change in any amino acid content, in either brain area. 3. In the group withdrawn from chronic diazepam, cortical 5-HT and 5-HIAA levels and hippocampal 5-HT levels were significantly increased. Noradrenaline content was significantly decreased in the hippocampus. 4. The changes in 5-HT and 5-HIAA levels following cat odour exposure were area-specific in that they decreased in the hippocampus, but increased in the cortex. 5. Following cat odour exposure, noradrenaline levels appeared not to change in either area studied. However during exposure to cat odour, it was found that half the animals avoided the odour source and half were indifferent. The animals showing marked avoidance had significantly higher cortical noradrenaline content and this was significantly different from control, whereas hippocampal noradrenaline levels were not dependent upon the differences in avoidance of the odour source. 6. The results show clearly different neurochemical changes in the rat following exposure to a phobic stimulus and withdrawal from diazepam. It is hoped comparative studies such as this will enable better understanding of anxiety states in the rat which could parallel the different classes of anxiety recognised in the clinic

Benzodiazepines increase preprocholecystokinin messenger RNA levels in rat brain

Using in situ hybridisation, the effects of acute and chronic diazepam administration and diazepam withdrawal on preprocholecystokinin (CCK) mRNA levels in discrete regions of rat brain were determined. In cerebral cortex and a subpopulation of hippocampal neurones, CCK mRNA levels were increased after a single injection of diazepam and 24 h after withdrawal from chronic diazepam treatment, but not after chronic diazepam treatment. These results show that, in some neuronal groups, CCK mRNA expression is regulated by benzodiazepines, although there is no clear link between CCK mRNA levels and anxiety state.

Transient and sustained components of the pupillary responses evoked by luminance and color

That the pupil reacts to changes in luminance and color, as well as to spatial features in the retinal image raises questions about whether phasic and tonic and/or color and luminance visual pathways project to the pretectal pupillomotor neurons. The present study compares pupillary responses evoked by heterochromatic and achromatic luminance increments to investigate whether the pupillary responses evoked by color and by luminance are independent of one another. Principal component analysis is used to examine the constituents of the pupil responses. The results support the belief that the visual input to the pupillomotor system is organized into phasic and tonic (but not necessarily independent color and luminance) pathways.

An object-based approach to medical process automation

The medical events of providers rendering services for patient care are necessarily interrelated. A clinical information system must reliably record these events and relate the information about their inter-dependency. The quality of clinical information therefore depends crucially on the proper coordination and tracking of these events according to established protocols. We introduce an object-based approach to define medical processes for their automation. For each medical process, we capture in one logical unit, an event-driven mechanism to coordinate of inter-dependent medical events of the process, and the data relevant to the process. We call the encapsulated unit a form object. Moreover, the form object may contain sub-objects each of which also encapsulates its own protocol knowledge and relevant information. In contrast to other approaches, the form object facilitates for administering medical processes due to its locality of definition, and its event-driven paradigm reflects medical events more naturally.

The role of 5-HT in the anxiogenic effects of acute ethanol withdrawal and in the long-lasting cognitive deficits

There was a significant increase in potassium-stimulated release of 3H-[5-HT] from hippocampal slices taken from rats withdrawn from chronic ethanol treatment, compared with control-treated rats. The anxiogenic behaviour observed 12 h after ethanol withdrawal was inhibited by the 5-HT1A partial agonist, buspirone (200 micrograms/kg s.c.), indicating that the increased 5-HT release might underlie the anxiogenic response. The ex-ethanol treated rats showed impaired habituation of motor activity in the holeboard and a reduced exploratory response. The latter, but not the former, were reversed by the 5-HT3 receptor antagonist, ondansetron (0.01 microgram/kg i.p.). Ondansetron was without effect on working memory errors, but significantly increased the number of reference memory errors made by the ex-ethanol group. It also had a significantly anxiogenic effect in this group. These results suggest that the chronic ethanol treatment changes the 5-HT system and has long-lasting effects on the function of 5-HT3 receptors.

Modification of chlordiazepoxide's behavioural and neurochemical effects by handling and plus-maze experience

The purpose of the present experiment was to determine how a rat's prior history (of repeated gentle handling and/or of the elevated plus-maze apparatus) modified the behavioural and neurochemical response to chlordiazepoxide. In handled animals one previous exposure to the plus-maze rendered the rats insensitive to the anxiolytic effects of chlordiazepoxide in this test. This phenomenon of 'one-trial tolerance' was not seen in unhandled rats and thus both prior handling and prior maze experience were necessary to abolish the behavioural response to chlordiazepoxide. The effects of chlordiazepoxide on K(+)-evoked [14C]GABA (gamma-aminobutyric acid) release were also modified by the rat's past history. The drug-induced reduction of GABA release in the cortex was abolished by prior plus-maze experience; whereas handling modified chlordiazepoxide's effects on GABA release in the hippocampus (the drug decreased release in unhandled rats and increased release in those given repeated gentle handling). Thus an anxiolytic response to chlordiazepoxide in the plus-maze was accompanied by reduced GABA release in both cortex and hippocampus. The 5-HT system (5-hydroxytryptamine) also proved sensitive to the rats' past history. The effects of chlordiazepoxide on K(+)-evoked [3H]5-HT release from the hippocampus depended on both prior handling and plus-maze experience and could be predicted from the undrugged level of evoked release; when this was low, chlordiazepoxide increased it, when it was high, chlordiazepoxide reduced it. These results raise the possibility that the beneficial effects of a benzodiazepine may depend on the baseline condition of the animals.

[The interrelationship between the O2-dependent bactericidal mechanism and hyperbilirubinemia of newborn]

In order to investigate the influence of indirect bilirubin to O2-dependent bactericidal mechanism in adult and newborn phagocytes we use the NBT reduction activity of granulocytes and monocytes as index, by infiltrated granulocytes and monocytes in different concentration of indirect bilirubin with or without latex stimulator. The NBT reduction activity of granulocytes infiltrated in 20 mg/dl indirect bilirubin will increase slightly, compared to uninfiltrated; but with latex stimulator, the increment will decrease significantly, this change is reversible, when indirect bilirubin be washed, the stimulating capacity by latex stimulator in granulocyte will be stronger; there were no such change pattern in monocytes. Since there were a big difference in NBT reduction activity of granulocytes and monocytes between newborns, with or without latex stimulator, we can't get a satisfied result. Indirect bilirubin in cells will increase NBT reduction activity of monocytes, but not in granulocytes.

Effect of nasolacrimal occlusion on timolol concentrations in the aqueous humor of the human eye

We studied the effect of manual nasolacrimal occlusion on the concentration of timolol in the aqueous humor of eyes of patients undergoing cataract extraction. Aqueous humor samples were obtained at various times after timolol maleate instillation from patients with or without 5 min of nasolacrimal occlusion; aliquots were assayed by HPLC. In patients receiving occlusion treatment, average timolol concentrations were statistically greater than those in control patients both between 15 and 90 min after instillation and also at 180 min. Pharmacokinetic analysis indicated that occlusion increased the concentration of timolol in the aqueous humor 1.7 times. In both groups, timolol concentrations were highest approximately 1 h after instillation. The decline in aqueous humor timolol concentrations occurred at similar rates in both groups.

Eradication of Helicobacter mustelae from the ferret stomach: an animal model of Helicobacter (Campylobacter) pylori chemotherapy

Colonization of the ferret stomach by Helicobacter mustelae has been suggested as a possible animal model for Helicobacter pylori-associated gastroduodenal disease of humans. Our study was designed to determine whether antimicrobial chemotherapy could eradicate H. mustelae from ferrets. Triple antimicrobial therapy combining amoxicillin, metronidazole, and bismuth subsalicylate was successful in eradicating the organism from 5 of 7 (71%) adult ferrets. Despite apparent in vitro susceptibility, neither chloramphenicol monotherapy nor a polytherapeutic regimen combining tetracycline, metronidazole, and bismuth subsalicylate proved effective in the eradication of H. mustelae. Several strains isolated after unsuccessful polytherapy showed markedly increased resistance to metronidazole. These preliminary findings are similar to results of H. pylori treatment trials with humans and suggest that the ferret may be a useful model for evaluating and comparing potential antimicrobial modalities for the eradication of H. pylori.

Oxygenation index in patients with meconium aspiration: conventional and extracorporeal membrane oxygenation therapy

The use of the alveolar-arterial oxygen difference P(A-a)O2 and the oxygenation index (mean airway pressure [Paw] FIO2 x 100/PaO2) have been proposed for selecting infants who will require extracorporeal membrane oxygenation (ECMO) therapy. However, the use of the oxygenation index (OI) in conjunction with Paw in an exclusive population of patients with meconium aspiration syndrome (MAS) has not been reported. Fourteen patients born in our facility and managed with conventional therapy and five infants treated with ECMO were enrolled in the study. All patients had clinical and x-ray evidence of MAS. Infants who received conventional treatment required mechanical ventilation greater than 48 h, FIO2 1.0, and were under the care and supervision of one neonatologist. Management was directed to minimize barotrauma by avoidance of routine hyperventilation, use of lower Paw, and sufficient expiratory time. One patient died before ECMO and 13 infants survived. Six survivors had an OI greater than 25 (three had an OI greater than 40), six had a Paw greater than or equal to 12 cm H2O (12 to 15 cm H2O in five infants) and six patients had a P(A-a)O2 greater than or equal to 610 torr. One surviving infant was transferred for ECMO therapy (OI 67, Paw 20 cm H2O). The five patients treated with ECMO survived (OI 48 to 92, Paw 20 to 29.5 cm H2O P(A-a)O2 627 to 650 torr). One patient in each group developed chronic lung disease with evidence of resting tachypnea. Our findings indicate that an OI greater than 40 in association with a Paw greater than or equal to 20 cm H2O may be helpful in predicting which infants with MAS need ECMO, whereas patients requiring a Paw less than or equal to 15 cm H2O can be managed with conventional therapy. An OI greater than or equal to 25 but less than 40 is not associated with high mortality in these patients. The predictive value of Paw of 16 to 20 cm H2O and the duration of an OI greater than 40 in patients with MAS need further investigation.

Plasma amino acid concentrations in premature infants: effect of sampling site

Amino acid concentrations in plasma obtained from infants by heel puncture differ from those in venous plasma primarily because of skin contamination but data from the two sites might agree more closely in premature infants because of their poorly developed sweat glands. To evaluate the importance of sampling site, amino acids were analyzed by a sensitive high-performance liquid chromatographic method in plasma obtained both by heel puncture and venipuncture in 14 premature infants. Histidine, tryptophan, alanine, aspartic acid, glycine, and serine were higher in capillary plasma. Tryptophan and glycine levels in capillary plasma correlated strongly with those in venous plasma. An additional wash with soap and water done in five infants did not eradicate the differences. Thus the lack of agreement between data from the two sites may be due to factors other than contamination.

Diversity of serotypes of Campylobacter jejuni and Campylobacter coli isolated in laboratory animals

One hundred nineteen isolates of Campylobacter jejuni and Campylobacter coli from nine laboratory animal species were serotyped using antisera to 20 Penner serotypes commonly isolated from cases of human enteric infections. Although C. jejuni and C. coli were isolated from laboratory animals with diarrhea, the majority were cultured from asymptomatic animals (81%). Seven of twenty-two isolates from animals with diarrhea were serotype 4 (32%) and three were serotype 1 (14%). Sixty-one of the 119 isolates (51%) were typeable using the 20 Penner antisera indicating that many of the isolates obtained from 29 nonhuman primates (five species), 20 ferrets, 7 hamsters, 15 cats and 48 dogs are serotypes commonly associated with human enteritis. Among typeable strains, 13 different serotypes were identified. Two particular serotypes, 4 and 19 were isolated from several species of animals and comprised 24% of the isolates studied. Since asymptomatic laboratory animals of several different species harbor serotypes of C. jejuni and C. coli that are potentially pathogenic to man, appropriate precautions should be instituted to minimize exposure of personnel to the organisms in laboratory animal feces. If suspected cases of zoonotic-related enteric campylobacteriosis involving laboratory animals do occur, serotyping of isolates would be a useful epidemiologic marker in studying the outbreak.

Cardiovascular changes in preterm infants nursed under radiant warmers

Radiant heat is known to increase insensible water loss and, to a certain extent, oxygen consumption. Little is known about its cardiovascular effects. We measured cardiac output, stroke volume, heart rate, and lower limb and skin blood flow in 20 preterm newborn infants nursed in an incubator and under a radiant warmer at an abdominal skin temperature of 36.5 degrees C. Mean (+/- SEM) birth weight was 1.57 (0.06) kg, gestational age 31.7 (0.4) weeks, and weight at examination 1.69 (0.02) kg; median postnatal age was 15 days. Skin and limb blood flow measurements increased by 44% to 55% with radiant heat (P less than .001 and P less than .01, respectively). Cardiac output increased by 5.4% (P less than .02) under the radiant warmer secondary to a small but significant (P less than .05) increase in heart rate. The changes in cardiac output during radiant heat administration are comparable to those reported for oxygen consumption.

Factors affecting nursery survival of very low birth weight infants

398 infants with birthweight (BW) 500-1500 g born from January 2 1982 to December 1983 were studied to determine incidence and survival rate by BW and gestational age (GA) categories and to determine causes of death and factors influencing mortality. 58% of the group survived. Factors other than those in the perinatal and postnatal period did not significantly influence survival. Infants with BW below 1000 g delivered by elective C-section had better survival than those delivered vaginally. Survival increased progressively with increasing BW and GA categories with GA more than BW being the limiting factor. Eleven (6.6%) of the deaths in the very low birth weight infants occurred during the nursery period after 28 days of age. These deaths would not have been addressed in the neonatal mortality.

Peripartum colloid osmotic pressures: correlation with serum proteins

Colloid osmotic pressure is a principal regulator of capillary fluid exchange. Alterations in colloid osmotic pressure in preeclamptic patients, as well as significant peripartum changes in colloid osmotic pressure in normotensive patients, are reported. In a study of 72 normotensive and preeclamptic patients, peripartum colloid osmotic pressure, serum albumin, and total serum protein were compared. Both groups exhibited significantly lower colloid osmotic pressure in the postpartum period than that measured antepartum. The mean antepartum colloid osmotic pressure in preeclamptic patients was significantly lower than in normotensive subjects. Regression equations were calculated [colloid osmotic pressure = 5.21 (total serum protein) -11.4 (r2 = 0.851)] and [colloid osmotic pressure = 8.1 (serum albumin) -8.2 (r2 = 0.891)]. Within the physiologic ranges most commonly reported for normotensive and preeclamptic patients, the use of these equations allowed calculation of colloid osmotic pressure to within 10% of measured values in 75 and 80% of the cases, respectively. Where direct measurement of colloid osmotic pressure is not readily available, calculated values may be helpful in patient management.

Cardiac output changes secondary to theophylline therapy in preterm infants

The cardiovascular effects of theophylline were studied in 11 clinically stable preterm infants. Theophylline was given as aminophylline using a loading dose of 6.8 mg/kg and a maintenance dose of 2 mg/kg every 8 hours intravenously. Cardiac output, stroke volume, and heart rate were measured using a combination of pulsed Doppler ultrasound and M-mode echocardiography. Compared with day 0, an increase was found in both cardiac output (P less than 0.01) and stroke volume (P less than 0.02) on days 1, 2, and 3. By day 7, stroke volume was comparable to pretreatment values, whereas cardiac output was still increased. Heart rate was augmented significantly (P less than 0.01) throughout the treatment period. Mean arterial blood pressure did not change. All but one of the neonates had serum theophylline concentrations between 6 and 13 mg/L. We conclude that both inotropic and chronotropic effects are evident during the first days of theophylline therapy. The metabolic cost of the increased cardiac output in the preterm infant with theophylline therapy deserves further attention.

Echocardiographic measurements in normal preterm and term neonates

To the purpose of better defining normative data on intracardiac dimensions and systolic time intervals in very low birth weight infants, we collected M-mode echocardiograms from 210 healthy preterm and term neonates with birth weights between 780 and 5,350 g and gestational ages ranging from 26 to 43 weeks. Fifty-nine neonates were less than 24 h, 62 were 25-48 h, and 89 were 48-144 h of age. Diastolic and systolic left ventricular dimensions increased gradually with advancing birth weight (r = +0.84 and 0.78). Left atrial and aortic root dimensions tended to show a parabolic relationship with birth weight, increments were reduced at higher birth weights (r = +0.92 and 0.85). The shortening fraction of the left ventricle (mean +/- SD 33.8 +/- 4.9%) and the left atrial/aortic ratio (1.16 +/- 0.10) were constant throughout all weight subgroups. Pre-ejection periods and ejection times of both ventricles were reduced in preterm infants due to their higher heart rates, but left and right ventricular PEP/ET ratios in preterm and term infants were comparable. Septal thickness in diastole and in systole tended to increase slowly with advancing birth weight, but correlation coefficients were low. This information is currently used as data base for a computer program to interpret M-mode echocardiograms performed in our nursery.

Deformability and intrinsic material properties of neonatal red blood cells

Whole cell and membrane deformability are essential for red blood cell (RBC) survival and for effective blood flow. Neonatal RBCs display several specific properties (eg, large size, high hemoglobin F) that could influence their deformation characteristics and contribute to their shortened life span. The present study was designed to compare selected rheologic properties (cellular deformability, pressure required to aspirate RBC into micropipettes, static and dynamic viscoelastic material properties) of neonatal and adult RBCs. RBC deformability, as studied by a rheoscope, was similar for neonates and adults over a shear stress range of 2.5 to 500 dyn/cm2. The pressure required to aspirate RBCs completely into 3.3-micron diameter pipettes was 129 +/- 87 dyn/cm2 for neonatal RBCs and 71 +/- 37 dyn/cm2 for adult RBCs. The aspiration pressure for neonatal and adult RBCs increased with increasing RBC volume, suggesting that the increased mean aspiration pressure for neonatal RBCs resulted from their larger volume. When RBCs with same volume and diameter were compared, the aspiration pressure tended to be smaller for neonatal RBCs than for adult cells. To characterize material properties determining RBC deformability, we measured membrane extensional (shear) and bending elastic moduli, the time constant for elastic recovery from extensional deformation and hemoglobin viscosity (ie, cytoplasmic viscosity) of neonatal and adult RBCs. Membrane surface viscosity and time constant for recovery from bending deformation were calculated. The extensional and bending moduli of neonatal RBCs were slightly smaller (10% and 16%, respectively) compared with adult cells. This suggests that the static resistance of neonatal RBC membrane to deformation and failure in response to a given force is slightly smaller. The time constant for recovery from extensional deformation of neonatal RBCs was larger by 14%, compared with adult cells. The time constant for bending deformation related to the RBC diameter and surface area was increased by 18% in the neonates. Membrane surface viscosity and hemoglobin viscosity were similar for both cell types. These results indicate that the deformability and viscoelastic properties of neonatal RBCs deviate only slightly from those of adult RBCs and that the increased aspiration pressure of neonatal RBCs is solely due to their large size. Some of the specific deformation characteristics observed in this study (increased aspiration pressure, decreased resistance to elastic deformation) may contribute to the shortened life span of neonatal RBCs.

Medium-chain triglycerides in infant formulas and their relation to plasma ketone body concentrations

A mild ketosis is known to prevail in the mother, fetus, and newborn infant during the 3rd trimester and in the early neonatal period. It has been shown that during an equivalent period in the rat ketone bodies are readily oxidized and serve as key substrates for lipogenesis in brain. Since medium-chain triglycerides are known to be ketogenic, preterm infants may benefit from dietary medium-chain triglycerides beyond the point of enhanced fat absorption. Our objective was to determine the ketogenic response in preterm infants (gestational age: 33 +/- 0.8 wk) fed three different isocaloric formulas by measuring the concentrations of 3-hydroxybutyrate and acetoacetate in the plasma of these infants. At the time of entrance to the study the infants were receiving 110 kcal/kg/24 h. Study I (11 infants): the infants were fed sequentially in the order; PM 60/40 (PM), Special Care Formula (SCF), and Similac 20 (SIM). In SCF greater than 50% of the fat consists of medium-chain length fatty acids while PM and SIM contain about 25%. The concentration of 3-hydroxybutyrate in plasma was significantly higher when infants were fed SCF than PM and SIM [0.14 +/- 0.03, 0.06 +/- 0.01, and 0.05 +/- 0.01 mM, respectively (p less than 0.01)]. Study II (12 infants); the infants were fed SCF, then SIM, or the reverse. The concentration of acetoacetate in plasma was 0.05 +/- 0.01 and 0.03 +/- 0.01 mM when infants were fed SCF and SIM, respectively (0.1 greater than p greater than 0.05). The concentrations of 3-hydroxybutyrate in plasma were similar to those measured in study I for the respective formulas.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood flow in the ascending and descending aorta in term newborn infants

The combination of 2-dimensional real-time and pulsed Doppler echocardiography provides a noninvasive method of measuring blood flow and has been used to study blood flow at the lower thoracic level in the descending aorta of the human fetus. Using these techniques, we evaluated the proportion of cardiac output distributed through the descending aorta in 20 healthy term newborn infants at 1-6 days of age. Blood flow in the ascending aorta was 759 +/- 135 ml/min (mean +/- S.D.) and in the descending aorta 482 +/- 92 ml/min indicating that 63.8% of the left ventricular output is distributed through the descending aorta. Peak systolic and mean blood flow velocities were comparable at the two sites, whereas the diameter of the descending aorta was 19% smaller than that of the ascending aorta. The changes in aortic blood flow were correlated with the changes in aortic diameter.

Neonatal jitteriness of unknown origin and circulating catecholamines

Jitteriness is a common problem affecting neonates. Although the cause can sometimes be determined by history or conventional laboratory evaluations, nevertheless, in many instances the cause of the jitteriness is unknown. To determine if either intracranial hemorrhage (ICH) or elevated catecholamines are responsible for jitteriness in neonates, we studied 34 healthy term neonates with normal hematocrits, serum glucose, Ca, Mg, Na, K and P. Thirteen of the infants had jitteriness as their only clinical problem. There were no differences in Apgar scores, birthweight, or gestational age in the two groups. Norepinephrine levels were significantly elevated in the jittery group as compared to the control group: 1276 +/- 574 vs. 914 +/- 338, p less than 0.05. Epinephrine levels were not different in the two groups. Intracranial hemorrhage was not found in any of the patients. Jittery neonates have increased sympathetic activity. What influence the increased levels have on other metabolic and hormonal systems is yet to be determined.

Cardiac output changes in newborns with hyperbilirubinemia treated with phototherapy

Phototherapy is known to increase peripheral blood flow in neonates, but information on the associated cardiovascular effects is not available. Using pulsed Doppler echocardiography we evaluated cardiac output and stroke volume in 12 preterm and 13 term neonates during and after phototherapy. We concomitantly measured arterial limb blood flow by strain gauge plethysmography and skin blood flow by photoplethysmography. Cardiac output decreased by 6% due to reduced stroke volume during phototherapy, whereas total limb blood flow and skin blood flow increased by 38% and 41%, respectively. Peripheral blood flow increments tended to be higher in the preterm than in the term infants. The reduced stroke volume during phototherapy may be an expression of reduced activity of the newborn during phototherapy. For healthy neonates the reduction in cardiac output is minimal, but for sick infants with reduced cardiac output, this reduction may further aggravate the decrease in tissue perfusion.

Pulsed Doppler determinations of cardiac output in neonates: normal standards for clinical use

Noninvasive monitoring of cardiac output can greatly facilitate the clinical assessment and management of neonates with cardiovascular compromise. To assess normal values of cardiac output in neonates, mean blood flow velocity was measured in the ascending aorta from a suprasternal approach using a range-gated, pulsed Doppler velocity meter, and aortic root diameter was determined from an M-mode echocardiogram. These techniques were combined, and cardiac output was evaluated in 59 healthy premature and 62 term newborn infants during the first week of life. Birth weights ranged from 780 g to 4,740 g and gestational age from 27 to 42 weeks. Cardiac output values increased linearly with advancing birth weight (r = +.94, P less than 0.001) and gestational age (r = +.95, P less than .001). Mean cardiac output values (+/- SD) per kilogram of body weight were 249 +/- 34 mL/min/kg and decreased with advancing birth weight: less than 1,500 g = 265 +/- 32 mL/min/kg; 1,500 to 2,500 g = 253 +/- 34 mL/min/kg; and greater than 2,500 g = 241 +/- 33 mL/min/kg. For clinical use, 325 mL/min/kg and 200 mL/min/kg can be used as upper and lower limits of normal, respectively. Doppler cardiac output estimates compared favorably with studies using invasive techniques.