Local GABAergic modulation of acetylcholine release from the cortex of freely moving rats

Cortical perfusion with GABA agonists and antagonists modulates the spontaneous release of cortical acetylcholine and GABA in freely moving rats. Twenty-four hours after implantation of a dialysis fibre, cerebral cortex spontaneously released acetylcholine (3.8 +/- 0.2 pmol/10 min) and GABA (6.6 +/- 0.4 pmol/10 min) at a stable rate. Local administration of GABA (1 or 5 mM) or the GABAA agonist muscimol (25 or 50 microM) had no effect on the spontaneous release of acetylcholine. However, bicuculline (1-25 microM), a GABAA antagonist, added to the dialysis perfusate, elicited a concentration-dependent increase of acetylcholine release to approximately double that of control. This effect of bicuculline (25 microM) was completely prevented by coperfusion with muscimol (50 microM). Local administration of the GABAB receptor agonist baclofen (10 or 50 microM) elicited a concentration-dependent increase in spontaneous acetylcholine release with a maximal increase of about 60%. Intracortical administration of baclofen also decreased the spontaneous release of GABA. The GABAB receptor antagonist CGP 35348 (1 mM), administered alone for 20 min through the dialysis fibre, was without effect on spontaneous acetylcholine release; however, it completely blocked both the baclofen-induced increase in acetylcholine release and the decrease in GABA release. These results suggest that cortically released GABA exerts a tonic influence on cholinergic activity.

Assessment of growth factor effects on post-thaw development of cryopreserved mouse morulae to the blastocyst stage

The objective of this study was to assess the influence of specific factors on post-thaw development of mouse cryopreserved morulae. Thawed morulae (n = 206) were randomly distributed between 10 treatment groups: medium alone control (CT), Vero (VR) cells, leukaemia inhibitory factor (1 ng/ml), interleukin-6 (1 ng/ml), transforming growth factor (TGF) alpha (2 ng/ml), epidermal growth factor (EGF) (4 ng/ml), platelet-derived growth factor (1 ng/ml), insulin-like growth factor (IGF)-I (30 ng/ml), IGF-II (1 ng/ml) and TGFbeta (2 ng/ml). At 4, 8, 20, 30 and 48 h, a digitized image of each thawed embryo was captured and stored for later analysis. The following parameters were examined: blastocoel formation, blastocyst expansion, zona thickness and hatching. At termination of the experiment, cell number per embryo was determined by bisbenzimide staining. When contrasted to the medium alone control, co-culture consistently accelerated the development of frozen-thawed morulae to the hatched blastocyst stage, allowing embryos to recover rapidly from any damage sustained during the cryopreservation process. While no single growth factor/cytokine was able to completely mimic the results achieved with co-culture, all of the growth factors impacted positively on at least one of the morphological parameters studied. Cell proliferation was significantly stimulated by just 48 h exposure to growth factors, either through co-culture or by direct media supplementation. Co-culture again yielded the best results with a mean cell count of 217 +/- 76 cells per blastocyst as compared with 131 +/- 36 in control medium alone. Amongst the factors tested, IGF-I, IGF-II and EGF had the greatest impact, with mean cell counts of 172 +/- 50, 168 +/- 50 and 179 +/- 55 respectively. Whereas only 5% of CT embryos developed to blastocysts with > 200 cells, 51% of thawed embryos placed on co-culture monolayers and 25-32% of embryos cultured with IGF-I, IGF-II or EGF had > 200 cells. This study for the first time systematically describes the effect of culture regimen and growth factor additives on the post-thaw development of cryopreserved embryos.

Alterations in cardiac and pulmonary function in pediatric rapid human immunodeficiency virus type 1 disease progressors. Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted Human Immunodeficiency Virus Study Group

OBJECTIVE

Infants with human immunodeficiency virus type 1 (HIV-1) can be divided into rapid progressors (RPs) and non-rapid progressors (non-RPs) based on symptoms and immunologic status, but detailed information about cardiac and pulmonary function in RP and non-RP children needs to be adequately described.

METHODOLOGY

Cardiac, pulmonary, and immunologic data and HIV-1 RNA burden were periodically measured in 3 groups: group I, 205 vertically infected children enrolled from 1990 to 1994 and followed through 1996; group II, a prospectively studied cohort enrolled at birth that included 93 infected (group IIa); and 463 noninfected infants (group IIb).

RESULTS

Mean respiratory rates were generally higher in group IIa RP than non-RP children throughout the period of follow-up, achieving statistical signifance at 1 month, 12 months, 24 months, 30 months, and 48 months of follow-up. Non-RP and group IIb (HIV-uninfected children) had similar mean respiratory rates from birth to 5 years of age. Significant differences in mean respiratory rates were found between group I RP and non-RP at 7 age intervals over the first 6 years of life. Mean respiratory rates were higher in RP than in non-RP at <1 year, 2.0 years, 2.5 years, 3.0 years, 3. 5 years, 4.0 years, and 6.0 years of age. Mean heart rates in group IIa RP, non-RP, and group IIb differed at every age. Rapid progressors had higher mean heart rates than non-RP at all ages through 24 months. Mean heart rates at 30 months through 60 months of age were similar for RP and non-RP children. Non-RP children had higher mean heart rates than did group IIb at 8 months, 24 months, 36 months, 42 months, 48 months, 54 months, and 60 months of age. In group I, RP had higher mean heart rates than non-RP at 2.0 years, 2.5 years, 3.0 years, and 4.0 years of age. After 4 years of age, the non-RP and RP had similar mean heart rates. Mean fractional shortening differed between the 3 group II subsets (RP, non-RP, and IIb) at 4, 8, 12, 16, and 20 months of age. Although mean fractional shortening was lower in RP than in non-RP in group II at all time points between 1 and 20 months, the mean fractional shortening was significantly lower in RP only at 8 months when restricting the statistical comparisons to the 2 HIV-infected groups (RP and non-RP). Mean fractional shortening increased in the first 8 months of life followed by a gradual decline through 5 years of age among group IIb children. No significant differences among the 3 groups in mean fractional shortening were detected after 20 months of age. In group I, differences between RP and non-RP in mean fractional shortening were detected at 1.5, 2.0, 2.5, and 3.0 years of age. After 3 years of age, group means for fractional shortening in RP and non-RP did not differ. Because of the limited data from the first months of the group I patients, it could not be determined whether this group experienced the gradual early rise in mean fractional shortening seen in the group II infants. In group IIa, RP had more clinical (eg, oxygen saturation <96%) and chest radiographic abnormalities (eg, cardiomegaly) at 18 months of life. RP also had significantly higher 5-year cumulative mortality than non-RP, higher HIV-1 viral burdens than non-RP, and lower CD8(+) T-cell counts.

CONCLUSIONS

Rapid disease progression in HIV-1- infected infants is associated with significant alterations in heart and lung function: increased respiratory rate, increased heart rate, and decreased fractional shortening. The same children exhibited the anticipated significantly increased 5-year cumulative mortality, increased serum HIV-1 RNA load, and decreased CD8(+) (cytotoxic) T-cell counts. Measurements of cardiopulmonary function in HIV-1-infected children seem to be useful in the total assessment of HIV-1 disease progression.

Parvovirus B19 infections

Infections caused by human parvovirus B19 can result in a wide spectrum of manifestations, which are usually influenced by the patient's immunologic and hematologic status. In the normal host, parvovirus infection can be asymptomatic or can result in erythema infectiosum or arthropathy. Patients with underlying hematologic and immunologic disorders who become infected with this virus are at risk for aplastic anemia. Hydrops fetalis and fetal death are complications of intrauterine parvovirus B19 infection.

Cytomegalovirus infection and HIV-1 disease progression in infants born to HIV-1-infected women. Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted HIV Infection Study Group

BACKGROUND AND METHODS

Cytomegalovirus (CMV) has been implicated as a cofactor in the progression of human immunodeficiency virus type 1 (HIV-1) disease. We assessed 440 infants (75 of whom were HIV-1-infected and 365 of whom were not) who had known CMV status and were born to HIV-1-infected women and who were followed prospectively. HIV-1 disease progression was defined as the presence of class C symptoms (according to the criteria of the Centers for Disease Control and Prevention [CDC]) or CD4 counts of less than 750 cells per cubic millimeter by 1 year of age and less than 500 cells per cubic millimeter by 18 months of age.

RESULTS

At birth the frequency of CMV infection was similar in the HIV-1-infected and HIV-1-uninfected infants (4.3 percent and 4.5 percent, respectively), but the HIV-1-infected infants had a higher rate of CMV infection at six months of age (39.9 percent vs. 15.3 percent, P=0.001) and continued to have a higher rate of CMV infection through four years of age (P=0.04). By 18 months of age, the infants with both infections had higher rates of HIV-1 disease progression (70.0 percent vs. 30.4 percent, P=0.001), CDC class C symptoms or death (52.5 percent vs. 21.7 percent, P=0.008), and impaired brain growth or progressive motor deficits (35.6 percent vs. 8.7 percent, P=0.005) than infants infected only with HIV-1. In a Cox regression analysis, CMV infection was associated with an increased risk of HIV-1 disease progression (relative risk, 2.59; 95 percent confidence interval, 1.13 to 5.95). Among children infected with HIV-1 alone, but not among those infected with both viruses, children with rapid progression of HIV-1 disease had higher mean levels of HIV-1 RNA than those with slower or no progression of disease.

CONCLUSIONS

HIV-1-infected infants who acquire CMV infection in the first 18 months of life have a significantly higher rate of disease progression and central nervous system disease than those infected with HIV-1 alone.

Unexpected non-HIV causes of death in children born to HIV-infected mothers. Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection Study Group

INTRODUCTION

A high incidence of sudden, unexplained deaths in infants born to HIV-infected mothers has been noted in several epidemiologic studies. During the course of a prospective study of heart and lung disease in children born to HIV-infected mothers, we noted that of 5 unexpected non-HIV-related deaths, 4 were attributed to traumatic events.

METHODS

The Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection (P2C2) study is a multicenter, prospective investigation of the incidence of heart and lung disease in HIV-infected children. A total of 805 children were enrolled and followed for 5 to 7 years with serial immunologic, pulmonary and cardiac function studies. During the study, a multidisciplinary committee was formed to review the cause of death for those patients who died. The committee used results of pulmonary, cardiac, and laboratory tests, hospital summaries, as well as autopsy and coroners' reports. The committee formed a consensus about the underlying and contributing causes of death for each subject using the definitions from the 1989 US Standard Certificate of Death.

RESULTS

A total of 121 deaths occurred during the course of the P2C2 study. Of the 121 deaths, 5 were traumatic or sudden and unexpected and judged by the Mortality Review Committee to be unrelated to HIV infection. The median age at the time of death was 1.3 months and ranged from 1.2 to 37.8 months. Two infants died of trauma: a skull fracture and subdural hematoma in 1 infant and multiple skeletal fractures consistent with battered child syndrome in the other infant. The third infant died of accidental suffocation at home at 1.2 months of age. The fourth infant died suddenly and unexpectedly at home at 1.3 months of age. The autopsy showed no sign of HIV or other infection and was consistent with sudden unexpected death or SIDS. One non-HIV-related death occurred when a 38-month-old child died together with the mother in an unwitnessed drowning. The cumulative mortality rate attributable to trauma and sudden death at 4 months of age was 0.95% (95% CI: 0.02-1. 87%) and the infant mortality rate was 9.5/1000 live births. Three children were born prematurely at 30, 33, and 36 weeks' gestational age, respectively, and 3 mothers admitted using recreational drugs before or during pregnancy.

DISCUSSION

These traumatic and sudden non-HIV-related deaths accounted for 4.1% (5/121) of the deaths during the entire P2C2 study period and for 20% (4/20) of the deaths in the first year of life. Four deaths were attributable to accidental and nonaccidental trauma rather than to other common causes of infant death. One death was a sudden unexpected death, similar to SIDS, a leading cause of infant death in the United States. The majority of previously reported non-HIV-related deaths in infants born to HIV-infected mothers have been attributed to SIDS or to unexplained sudden death. In contrast with other reports, 4 of the 5 children in our series died of accidental or nonaccidental trauma and only 1 was a sudden unexplained death. It is unlikely that HIV exposure is related directly to the deaths described in this report; however, maternal HIV infection may be a marker for factors that place the child at risk for sudden or traumatic death.

SUMMARY

This report suggests that children born to HIV-infected mothers may be at increased risk for traumatic or sudden, unexplained, non-HIV-related death. These children seem to be at risk regardless of their own HIV infection status. Furthermore, 4 of the deaths in our study occurred within the first few months of life, suggesting that this is a period of increased vulnerability. Studies to identify associated risk factors for non-HIV-related deaths are needed to identify these high-risk infants. Children born to HIV-infected mothers may be more vulnerable than was recognized previously and may be in need of increased social services, especially in early infancy.

Evaluation of the effect of interleukin-6 and human extracellullar matrix on embryonic development

Extracellular matrices and their associated growth factors can modulate the in-vitro growth of cells. In this study, the effects of culture substrata and the cytokine interleukin-6 (IL-6) on embryonic development were investigated. In-vitro fertilized mouse oocytes were pooled and randomly distributed amongst treatment groups. The test treatments were: (i) IL-6, at either 500 or 1000 pg/ml; (ii) human extracellular matrix (HECM) applied to organ culture dishes at either 5.0 or 10.0 microg/ml; and (iii) HECM and IL-6 combined. A total of 1285 embryos was evaluated. The effect of IL-6 on embryos was dose dependent. Treated embryos exhibited higher blastulation and hatching rates than untreated control embryos. Culture of embryos on human matrix proteins versus standard culture surfaces significantly improved in-vitro hatching. The combination of both of these treatments was superior to the medium alone control, and the mean cell count per blastocyst was higher (131.7 +/- 29.7 versus 82. 5 +/- 14.3 in control embryos; P < 0.0001). In a pilot study with human triploid embryos, the HECM/IL-6 culture system appeared to support embryonic compaction, blastulation and hatching. This work suggests that extracellular matrix components in combination with growth factors/cytokines may be another avenue for formulating more physiological culture systems.

Sternal wound and mediastinal infections in infants with congenital heart disease

The objective was to describe the epidemiologic, clinical, bacteriologic and therapeutic features of seven infants who developed sternal wound and mediastinal infections following palliation and/or repair procedures for congenital heart disease. A retrospective chart review was used. All infants with sternal wound and mediastinal infections were < 30 days of age at the initial operative procedure. Six of the infants had hypoplastic left heart syndrome, and one had complete transposition. Two infants required delayed closure of their chest wound. Three infants had superficial sternal infections and presented at a mean of 12 days postoperatively. Four infants had infection of the deep mediastinal structures: they were all asymptomatic and had purulent collections in their mediastinum at their second palliative operation, which was performed at a mean of 120 days after the initial surgery. Staphylococcus aureus, or coagulase-negative Staphylococcus, was isolated from the wound and/or blood of six infants. All infants with mediastinal infections were managed with operative debridement. Infants with superficial infections underwent local debridement. All infants received long-term intravenous antibiotics. Mediastinal infections in infants undergoing palliative staged procedures for congenital heart lesions may be chronic and indolent, resulting in delayed repair of congenital heart lesions.

Beneficial effects of estrogen on cardiac stunning in female rabbits

OBJECTIVE

To determine the effect of estrogen treatment on the contractile, relaxation, and chronotropic responses of hearts of female rabbits to cessation of perfusion.

METHODS

Adult female rabbits were treated either with estradiol or with the vehicle (control). The hearts were then isolated and perfused at constant pressure by the Langendorff technique. A saline-filled balloon connected to a pressure transducer was inserted in the left ventricle in order to assess the mechanical function of the isolated heart. Cardiac stunning was induced by halting the perfusion of the coronary vasculature for four successive periods of 1, 3, 5, and 5 minutes, followed by reperfusion between nonperfusion periods. Changes in cardiac function induced by the cessation of perfusion were assessed by monitoring the changes in heart rate and in left ventricular pressure ([dP/dt]max as an index of ventricular contractility and [dP/dt]min as an index of ventricular relaxation). Changes in coronary flow were determined at baseline and following reperfusion.

RESULTS

Halting coronary perfusion decreased (dP/dt)max, and (dP/dt)min and slowed left ventricular contractions both in control and in estrogen-treated hearts. The depressant effects of flow cessation on left ventricular (dP/dt)max and (dP/dt)min were smaller in estrogen-treated hearts than in control hearts. Treatment with estrogen had no effect on the changes on the heart rate in responses to cessation of flow and to reperfusion. Treatment with estrogen increased coronary flow by 40%. Coronary reperfusion increased coronary flow transiently, but the effects did not differ significantly between control and estrogen-treated hearts.

CONCLUSION

Short-term treatment of adult female rabbits with doses of estrogen that are physiologic for the rabbit exerts a protective effect on cardiac contractility from repetitive periods without perfusion.

Pleiotropic behavior of 5-HT2A and 5-HT2C receptor agonists

There is now considerable evidence that a single receptor subtype can couple to multiple effector pathways within a cell. Recently, Kenakin proposed a new concept, termed "agonist-directed trafficking of receptor stimulus", that suggests that agonists may be able to selectively activate a subset of multiple signaling pathways coupled to a single receptor subtype. 5-HT2A and 5-HT2C receptors couple to phospholipase C-(PLC) mediated inositol phosphate (IP) accumulation and PLA2-mediated arachidonic acid (AA) release. Relative efficacies of agonists (referenced to 5-HT) differed depending upon whether IP accumulation or AA release was measured. For the 5-HT2C receptor system, some agonists (e.g. TFMPP) preferentially activated the PLC-IP pathway, whereas others (e.g. LSD) favored PLA2-AA. As expected, EC50's of agonists did not differ between pathways. For the 5-HT2A receptor system, all agonists tested had greater relative efficacy for PLA2-AA than for PLC-IP. In contrast, relative efficacies were not different for 5-HT2A agonists when sequential effects in a pathway were measured (IP accumulation vs. calcium mobilization). These data strongly support the agonist-directed trafficking hypothesis.

Maternal and perinatal factors related to maternal-infant transmission of HIV-1 in the P2C2 HIV study: the role of EBV shedding. Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted HIV-1 Infection (P2C2 HIV) Study Group

The association of maternal and perinatal factors with mother-infant transmission of HIV-1 was examined in a prospective multicenter cohort of singleton live births to 508 HIV-1-infected women with children of known HIV-1 infection status (91 [18%] HIV-1-infected, 417 [82%] uninfected). From multivariate logistic regression, independent predictors of HIV-1 transmission included maternal CD4 percentage (CD4%) (odds ratio [OR] per 10% increase in CD4% = 0.70; p = .003), ruptured membranes <24 hours (OR = 3.15; p = .02), and maternal bleeding (OR = 2.90; p = .03), whereas maternal zidovudine (ZDV) use was marginally associated (OR = 0.60; p = .08). The associations of maternal urinary cytomegalovirus (CMV) shedding, oropharyngeal Epstein-Barr virus (EBV) shedding, and serology profiles during pregnancy with HIV-1 transmission were examined in the subset of mothers in whom the CMV and EBV measurements were available. Maternal EBV seropositivity, CMV shedding, and CMV seropositivity were 100% (279 of 279), 7% (16 of 229), and 92% (270 of 274), respectively. These rates did not differ between transmitting and nontransmitting mothers. In univariate analyses, maternal EBV shedding was higher among transmitting than nontransmitting mothers (40 of 49 [82%] compared with 154 of 226 [68%]; p = .06) and was independently associated with transmission in multivariate logistic analyses adjusting for CD4%, ruptured membranes, and ZDV use, with an OR of 2.45 (95% confidence interval (CI), 1.03-5.84; p = .04). This permits the conclusion that EBV shedding is associated with maternal-infant HIV-1 transmission, independent of CD4%.

Superficial venous thrombosis presenting as a painful popliteal fossa mass in a child

We report an unusual case of superficial venous thrombosis in a cyanotic 12-year-old child who had undergone recent appendectomy. Although compression, color Doppler, and duplex ultrasound techniques remain the keys to the diagnosis of venous thrombosis, SieScape sonography was beneficial in demonstrating the extent of the thrombi and their location along a superficial thrombosed vein.

Effects of estrogen on tight junctional resistance in cultured human umbilical vein endothelial cells

OBJECTIVE

To study the effects of estrogen on transendothelial paracellular permeability in women.

METHODS

Human umbilical vein endothelial cells (HUVEC) obtained from women were grown on filters. The paracellular permeability characteristics were determined in terms of changes in the permeability to the polar acid pyranine (Ppyr) and as changes in the transendothelial electrical resistance (RTE). Tight junctional resistance characteristics were assayed by lowering luminal NaCl and measuring the dilution potential, and were expressed as the ratio of monoion mobility uCl/uNa (cation selectivity).

RESULTS

Low extracellular calcium and hyperosmolarity increased Ppyr and decreased RTE. The former but not the latter condition abolished the endothelium-specific cation selectivity. Treatment with 10 nM of estradiol-17 beta had no effect on RTE, but it increased the cation selectivity. The effect of estradiol required 1-6 hours' incubation with the hormone; it was dose dependent and saturable, with a median effective concentration of estradiol of 1 nM. Diethylstilbestrol, but not estriol, could mimic the effect of estradiol, and the estrogen receptor antagonist ICI-182, 780 blocked it.

CONCLUSION

Cultured HUVEC cells form patent tight junctions. Estrogens increase the cation selectivity across HUVEC cultures. The effect of estrogen may be mediated by an estrogen receptor. These effects may be important for vasculoprotection in cases of sudden changes in ions levels across the capillary wall, such as ischemia or reperfusion.

Modulation of coronary vascular resistance in female rabbits by estrogen and progesterone

OBJECTIVE

To study the roles of estradiol and various progestins on the regulation of coronary flow in female rabbits.

METHODS

Ovariectomized adult female rabbits were treated with estradiol, with progesterone (or one of the following synthetic progestins: megace, norethindrone, or medroxyprogesterone acetate), or with both an estradiol and a progestin. Hearts were isolated and perfused at constant pressure by a modified Langendorff technique. Changes in coronary flow were determined at baseline and in response to direct infusion into the coronary circulation of NG-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide (NO) synthase.

RESULTS

Coronary flow rates were 40-50% greater in hearts of animals treated with estradiol than in control hearts of animals not treated with the hormone. Treatment of the animals with progestin alone had little effect on coronary flow. However, when administered with estradiol, it abrogated the estradiol-related increase in coronary flow. The increments in coronary flow evoked by estradiol were virtually abolished by L-NNA, an inhibitor of NO synthase. In hearts of animals treated with estradiol plus progesterone, L-NNA had no additional inhibitory effect on coronary flow to that of progesterone.

CONCLUSION

Estradiol decreases coronary vascular resistance (CVR) and hence increases coronary flow. Progestins attenuate this effect of estradiol.

Effector pathway-dependent relative efficacy at serotonin type 2A and 2C receptors: evidence for agonist-directed trafficking of receptor stimulus

There are many examples of a single receptor coupling directly to more than one cellular signal transduction pathway. Although traditional receptor theory allows for activation of multiple cellular effectors by agonists, it predicts that the relative degree of activation of each effector pathway by an agonist (relative efficacy) must be the same. In the current experiments, we demonstrate that agonists at the human serotonin2A (5-HT2A) and 5-HT2C receptors activate differentially two signal transduction pathways independently coupled to the receptors [phospholipase C (PLC)-mediated inositol phosphate (IP) accumulation and phospholipase A2 (PLA2)-mediated arachidonic acid (AA) release]. The relative efficacies of agonists differed depending on which signal transduction pathway was measured. Moreover, relative to 5-HT, some 5-HT2C agonists (e.g., 3-trifluoromethylphenyl-piperazine) preferentially activated the PLC-IP pathway, whereas others (e.g., lysergic acid diethylamide) favored the PLA2-AA pathway. In contrast, when two dependent responses were measured (IP accumulation and calcium mobilization), agonist relative efficacies were not different. These data strongly support the hypothesis termed "agonist-directed trafficking of receptor stimulus" recently proposed by Kenakin [Trends Pharmacol Sci 16:232-238 (1995)]. Concentration-response curves to 5-HT2C agonists were fit well by a three-state model of receptor activation, suggesting that two active receptor states may be sufficient to explain pathway-dependent agonist efficacy. Rational drug design that optimizes preferential effector activity within a group of receptor-selective drugs holds the promise of increased selectivity in clinically useful agents.

Randomized, single-blinded comparative study of the efficacy of amoxicillin (40 mg/kg/day) versus standard-dose penicillin V in the treatment of group A streptococcal pharyngitis in children

A 10-day course of amoxicillin at a dosage of 40 mg per kilogram per day was compared with conventional (lower dosage) penicillin V therapy in the treatment of culture-proven Group A streptococcal pharyngitis in children 3 to 18 years of age in a prospective, randomized, and single-blinded study. Children had to have signs and symptoms compatible with the diagnosis of streptococcal pharyngitis and to have a throat swab positive for Group A streptococci. A second throat culture was obtained 10 to 14 days after the completion of therapy. Serotyping was performed to help differentiate carrier states from reinfections. Of 161 children enrolled, 113 were evaluable; 55 received penicillin and 58 received amoxicillin. At the completion of therapy 70.9% (39/55) of patients in the penicillin group vs 87.9% (51/58) of patients in the amoxicillin group were asymptomatic (clinical cure, P = 0.025). At the completion of therapy, 54.5% (30/55) of patients in the penicillin group vs 79.3% (46/58) of patients in the amoxicillin group had negative throat cultures (bacteriologic cure, P = 0.005). The carrier rate (children who were well but who were still carrying the same serotype of Group A streptococcus) also differed between the groups: 13 (23.6%) in the penicillin group compared with six (10.3%) in the amoxicillin group. Amoxicillin at 40 mg/kg/day was significantly more effective than lower dosages of penicillin V for clinical and bacteriologic cure in the treatment of Group A streptococcal pharyngitis in children. The current perception that penicillin is declining in effectiveness may be due to inadequate dosing.

Co-cultured human embryos may be subjected to widely different microenvironments: pattern of growth factor/cytokine release by Vero cells during the co-culture interval

This study was designed to identify and quantify concentrations of growth factors/cytokines released by Vero cells during the co-culture interval. The factors screened for in this preliminary investigation, namely platelet-derived growth factor (PDGF), transforming growth factor beta (TGFbeta), interleukin-6 (IL-6), leukaemia inhibitory factor (LIF) and epidermal growth factor (EGF) have each been identified to impact on early embryo development or are secreted by embryos themselves, suggesting an autocrine regulatory role. Vero cell culture supernatants were collected at 2, 3, 4, 5 and 6 days after seeding. Samples were assessed by enzyme-linked immunoassay for growth factor/cytokine secretion at each designated time interval. Conditioned medium from all days contained IL-6, PDGF and LIF. The concentration of IL-6 increased from 294 pg/well on day 2 to almost 1600 pg/well on day 6. PDGF also accumulated rapidly in co-culture wells, rising from 19-40 pg/well early in the culture period to around 500 pg/ well by day 6. In the second half of this study, medium supernatants from patients enrolled in our co-culture programme were analysed. Retrospective evaluation of medium supernatants collected at the time of transfer from co-cultures from 11 randomly selected patients showed considerable patient-to-patient variation in concentrations of secreted growth factors and cytokines. These findings indicate that during the co-culture interval embryos are exposed to a dynamic environment, with increasing concentrations of growth factors and cytokines. The positive effects of co-culture on embryo quality and in-vitro blastulation need to be balanced against the variation that this technique can potentially introduce into the embryo culture system.

Serotonergic modulation of acetylcholine release from cortex of freely moving rats

The modulation of acetylcholine (ACh) release by 5-HT3 receptor activation was studied using in vivo microdialysis. Spontaneous and K+-stimulated ACh release were measured in frontoparietal cortex and hippocampus of freely moving rats. Two consecutive exposures to high K+ produced ACh release of similar magnitude. In the cortex, serotonin (5-HT) failed to alter spontaneous ACh release, but caused a concentration-dependent decrease of K+-evoked ACh release. Phenylbiguanide (PBG) and m-chlorophenylbiguanide, two selective 5-HT3 agonists, mimicked the 5-HT responses, but 8-hydroxy-2-(di-n-propylamino)tetralin, a selective 5-HT1A agonist, was without effect. However, PBG failed to modify K+-evoked ACh release from the hippocampus. Systemic and local administration of a highly selective 5-HT3 antagonist, tropisetron ((3-alpha-tropanyl)1H-indole-carboxylic acid ester) blocked the effect of both 5-HT and PBG. The inhibition of ACh release by PBG was sensitive to tetrodotoxin. These observations provide direct evidence that, in rat cortex, 5-HT modulates in-vivo release of ACh through activation of 5-HT3 receptors.

Parvovirus: a review

Infections caused by human parvovirus B19 result in a variety of clinical manifestations, the severity of which depends on the immune and hematologic status of the host. Arthropathy is known to occur in children and adults with acute parvovirus B19 infection. In adults, the arthropathy is common and is usually brief and self-limited, although a chronic arthropathy due to HPV B19 infections can occur rarely. It is important to differentiate between such chronic infection and RA, because of the similar clinical manifestations and different modes of treatment. An association between HPV B19 and other rheumatologic diseases such as vasculitis needs further research before confirmation is possible.

Infectious diseases presentations of Munchausen syndrome by proxy: case report and review of the literature

Munchausen syndrome by proxy is a form of abuse, usually of a child by a parent, in which a factitious illness is reported or produced in the child, resulting in unnecessary medical evaluations and treatments. A dramatic case of a 17-month-old infant with recurrent polymicrobial bacteremia prompted a review of cases diagnosed by the Pediatric Infectious Diseases consultation service at our referral children's hospital and a review of the infectious diseases presentations in the medical literature. The infectious diseases presentations of the syndrome as well as criteria for the diagnosis are reviewed and discussed.

HIV vertical transmission rate determinations are subject to differing definitions and therefore different rates. The Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted HIV Infection Study Group

The HIV infection status of a cohort of 600 prospectively followed children born to HIV infected mothers was determined using HIV peripheral blood culture tests at 0, 3, and 6 months of age, HIV serology at > or = 15 months, and CDC AIDS criteria. We estimated transmission rates using five methods which differed in how HIV indeterminates are handled. These methods were applied at two points in time to illustrate effects of length of follow-up of the cohort on results. In January 1997, 30 months after the last birth, transmission rate estimates ranged from 15.5% (known positives/known positives x known negatives) to 18.1% (known positives x those with one positive culture x deaths/entire cohort minus those lacking negative cultures at age > or = 5 months). Estimates ranged from 14.8% to 20.7% using the subcohort of 284 children followed > or = 12 months as of May 1993. These results indicate that methods for assigning HIV infection status and for handling HIV indeterminates should be carefully defined when estimating transmission rates.