Validation of transcutaneous bilirubinometry during phototherapy for detection and monitoring of neonatal jaundice in a low-income setting

Background: Severe neonatal jaundice (SNJ) and the associated long-term health sequelae are a significant problem in low-income countries (LIC) where measurement of total serum bilirubin (TSB) is often unavailable. Transcutaneous bilirubinometry (TcB) provides the opportunity for non-invasive, point-of-care monitoring. Few studies have evaluated its agreement with TSB levels during phototherapy in LIC.Aim: To determine agreement between TcB and TSB during phototherapy in a Haitian newborn population and to establish whether TcB can be safely used to guide treatment during phototherapy when TSB is unavailable.Methods: A single-centre prospective study (February to May 2017) in Cap Haïtien, northern Haiti was undertaken. Newborns <7 days of age with clinically detected jaundice were eligible for inclusion. A TcB device (JM-103) was used to screen for newborn jaundice along with a parallel TSB. A strip of black tape was placed across the sternum during phototherapy and uncovered for subsequent TcB measurements. Decisions about phototherapy treatment were based upon UK National Institute of Clinical Excellence (NICE) threshold criteria. Paired TSB and TcB measurements were compared using Bland-Altman methods.Results: The final analysis included 70 parallel TSB/TcB measurements from 35 infants within the first 5 days of life. Nineteen (54.3%) were male and 12 (34.3%) were <35 weeks. Thirty-two (91.4%) were receiving phototherapy. There was good agreement between TSB and TcB. Compared with TSB, TcB tended to over-estimate bilirubin (mean difference 11.1 µmol/L, 95% CI -10.2-32.5 µmol/L). However, at higher bilirubin levels (>250 µmol/L), TcB tended to under-estimate bilirubin compared with TSB and the difference increased.Conclusion: In an LIC setting in which serum bilirubin testing is not commonly available, TcB demonstrates good agreement with TSB and can be safely used to guide jaundice treatment during phototherapy but can lead to over-treatment at lower bilirubin levels and are more inaccurate at higher levels. For TcB levels >250 µmol, confirmation with serum bilirubin should be performed, if available, to avoid under-estimation.Abbreviations: LIC: low income countries; LMIC: low and middle income countries; TcB: transcutaneous bilirubinometry; TSB: transcutaneous serum biliubin.

A technique for re-utilizing catheter insertion sites in children with difficult central venous access

Maintenance of central venous access in patients with chronic medical conditions such as short bowel syndrome demands forethought and ingenuity. We describe an innovative technique for re-utilizing central venous access sites in patients who have chronic central venous access needs. Records of patients undergoing this technique were reviewed between August 2012 and December 2015. The technique involves "cutting-down" to the sterile fibrous tunnel that naturally forms around tunneled catheters. The fibrous sheath is then isolated and controlled much as would be done for a venous "cut-down." A separate exit site is then created for the new catheter and it is tunneled to the "cut-down" site per routine. The non-functioning catheter is then removed from the surgical field. The proximal fibrous sheath is finally cannulated either directly with the new catheter or with a wire/dilator system. This technique effectively re-uses the same venous access point while allowing for a complete change of the physical line and external site. Twenty attempts at this technique were made in twelve patients; six patients underwent the site re-utilization procedure multiple times. Re-using the fibrous tunnel to re-cycle the internal catheter site was successful in seventeen of twenty attempts. All patients had chronic conditions leading to difficult long-term central venous access [short bowel syndrome (6), hemophilia (2), cystic fibrosis (1), chronic need for central IV access (3)]. Indications for catheter replacement included catheter occlusion/mechanical failure/breakage (9), dislodgement (6), infection (1), and inadequate catheter length due to patient growth (4). Broviac/Hickman catheter sites were most commonly re-used (13; one failure); re-using a portcath site was successful in 5 of 7 attempts. There were no short term infections or mechanical complications. We describe a novel technique for salvaging tunneled central venous catheter access sites. This technique is well suited for patients with difficult and long-term central venous access needs, particularly those with chronic conditions such as intestinal failure. It is specifically useful when tunneled lines are broken, precipitated or clotted and unamenable to wiring.

Reactivation of coccidioidomycosis: a prosthetic joint infection in Spain

A resident of Spain was found to have a prosthetic knee infection due to coccidioidomycosis. He had a history of having pneumonia which resolved while living in an area of California endemic for Coccidioides in 1957-1961. The patient left California in 1961 returned to Spain and never left Spain thereafter. In 2006, a total knee replacement was done. In 2013, a prosthetic knee infection was documented due to coccidioidomycosis. By molecular DNA analysis, Coccidioides immitis was identified from the knee tissue, a species most commonly found in California. This represents reactivation of a Coccidioides infection 56 years after leaving the endemic area.

Arm versus forearm tourniquet for carpal tunnel decompression - Which is better? A randomized controlled trial

Tourniquet pain is a common source of complaint for patients undergoing carpal tunnel decompression and practice varies as to the tourniquet position used. There is little evidence to suggest benefit of one position over another. Our aim was to compare patient and surgeon experience of forearm and arm tourniquets. Following a power calculation, 100 patients undergoing open carpal tunnel decompression under local anaesthetic were randomized to either an arm or a forearm tourniquet. Measurements of blood pressure, heart rate and pain were taken at 2.5 min intervals. The operating surgeon also provided a visual analogue scale rating for the extent of bloodless field achieved and for any obstruction caused by the tourniquet. There was no statistically significant inter-group difference in patient pain or physiological response, tourniquet time, bloodless field or length of procedure. The degree of obstruction caused by the tourniquet was significantly higher in the forearm group.

LEVEL OF EVIDENCE

I. Prospective Randomized Controlled Trial.

A reliable surgical treatment for digital mucous cysts

There is no clear consensus about the best operative technique for the treatment of digital mucous cysts. We carried out a retrospective review of all patients who underwent excision of a digital mucous cyst using a local advancement skin flap over a 10-year period. A total of 69 patients were included and were reviewed at an average of 38 months (minimum 6 months) post-operatively. No patients were lost to follow-up. There was only one case of cyst recurrence. Of these 67 patients were happy with the scar and 63 patients said they would have the procedure again; 36 patients had a pre-operative nail deformity and 21 reported that the deformity grew out after the procedure.

Single incision Nuss procedure for pectus excavatum

PURPOSE

To describe a unique single incision modification of the Nuss procedure and compare results to a historical cohort of standard Nuss patients.

METHODS

A retrospective review of 32 patients who underwent the Nuss procedure at a tertiary academic medical center over a 4-year period (2007-2010). Fourteen consecutive patients who underwent the modified technique (MN) were compared to the previous 18 patients who underwent the standard procedure (SN). We evaluated for differences between group demographics, operative variables, and postoperative course. The major technical modification was performing the entire procedure through a single right lateral thoracic incision. The dissection for bar placement on the left side of the chest was performed in a subcutaneous, pre-sternal and pre-muscular plane from the right-sided incision. The bar was placed from the right side and positioned in the standard fashion. Thoracoscopy was preformed via the same incision using a 45-degree thoracoscope and multiple trocar positions. The bar was anchored to the chest wall with a unilateral bar stabilizer.

RESULTS

There were no statistically significant differences between the study groups in any of the patient, operative or postoperative care parameters.

CONCLUSION

The single incision modified Nuss procedure is as safe and efficacious as the standard technique.

Delta-opioid receptor activation prolongs respiratory motor output during oxygen-glucose deprivation in neonatal rat spinal cord in vitro

Delta opioid receptor (DOR) activation protects the adult mammalian brain during oxygen-glucose deprivation (OGD), but it is not known whether neonatal spinal motor circuits are also protected. Also, it is unclear whether the timing of spinal DOR activation relative to spinal OGD is important for neuroprotection. Thus, a split-bath in vitro neonatal rat brainstem/spinal cord preparation was used to record spontaneous respiratory motor output from cervical (C4-C5) and thoracic (T5-T6) ventral spinal roots while exposing only the spinal cord to OGD solution (0 mM glucose, bubbled with 95% N(2)/5% CO(2)) or DOR agonist drugs (DADLE, DPDPE). Spinal OGD solution application caused respiratory motor output frequency and amplitude to decrease until all activity was abolished (i.e. end-point times) after 25.9±1.4 min (cervical) and 25.2±1.4 min (thoracic). Spinal DOR activation via DPDPE (1.0 μM) prior-to and during spinal OGD increased cervical and thoracic end-point times to 35-48 min. Spinal DADLE or DPDPE (1.0 μM) application 15 min following spinal OGD onset increased cervical and thoracic end-point times to 36-45 min. Brief spinal DPDPE (1.0 μM) application for 10 min at 25 min before spinal OGD onset increased cervical and thoracic end-point times to 41-46 min. Overall, the selective DOR agonist, DPDPE, was more effective at increasing end-point times than DADLE. Naltrindole (DOR antagonist; 10 μM) pretreatment blocked DPDPE-dependent increase in end-point times, suggesting that DOR activation was required. Spinal naloxone (1.0 μM) application before and during spinal OGD also increased end-point times to 31-33 min, but end-point times were not altered by Mu opioid receptor (MOR) activation or DOR activation/MOR blockade, indicating that there are complex interactions between OGD and opioid signaling pathways. These data suggest DOR activation before, during, and after spinal OGD protects central motor networks and may provide neuroprotection during unpredictable perinatal ischemic events.

Changes in ventral respiratory column GABAaR ε- and δ-subunits during hibernation mediate resistance to depression by EtOH and pentobarbital

During hibernation in the 13-lined ground squirrel, Ictidomys tridecemlineatus, the cerebral cortex is electrically silent, yet the brainstem continues to regulate cardiorespiratory function. Previous work showed that neurons in slices through the medullary ventral respiratory column (VRC) but not the cortex are insensitive to high doses of pentobarbital during hibernation, leading to the hypothesis that GABA(A) receptors (GABA(A)R) in the VRC undergo a seasonal modification in subunit composition. To test whether alteration of GABA(A)R subunits are responsible for hibernation-associated pentobarbital insensitivity, we examined an array of subunits using RT-PCR and Western blots and identified changes in ε- and δ-subunits in the medulla but not the cortex. Using immunohistochemistry, we confirmed that during hibernation, the expression of ε-subunit-containing GABA(A)Rs nearly doubles in the VRC. We also identified a population of δ-subunit-containing GABA(A)Rs adjacent to the VRC that were differentially expressed during hibernation. As δ-subunit-containing GABA(A)Rs are particularly sensitive to ethanol (EtOH), multichannel electrodes were inserted in slices of medulla and cortex from hibernating squirrels and EtOH was applied. EtOH, which normally inhibits neuronal activity, excited VRC but not cortical neurons during hibernation. This excitation was prevented by bicuculline pretreatment, indicating the involvement of GABA(A)Rs. We propose that neuronal activity in the VRC during hibernation is unaffected by pentobarbital due to upregulation of ε-subunit-containing GABA(A)Rs on VRC neurons. Synaptic input from adjacent inhibitory interneurons that express δ-subunit-containing GABA(A)Rs is responsible for the excitatory effects of EtOH on VRC neurons during hibernation.

Somatic p16(INK4a) loss accelerates melanomagenesis

Loss of p16^INK4a–RB and ARF–p53 tumor suppressor pathways, as well as activation of RAS–RAF signaling, is seen in a majority of human melanomas. Although heterozygous germline mutations of p16^INK4a are associated with familial melanoma, most melanomas result from somatic genetic events: often p16^INK4a loss and N-RAS or B-RAF mutational activation, with a minority possessing alternative genetic alterations such as activating mutations in K-RAS and/or p53 inactivation. To generate a murine model of melanoma featuring some of these somatic genetic events, we engineered a novel conditional p16^INK4a-null allele and combined this allele with a melanocyte-specific, inducible CRE recombinase strain, a conditional p53-null allele and a loxP-stop-loxP activatable oncogenic K-Ras allele. We found potent synergy between melanocyte-specific activation of K-Ras and loss of p16^INK4a and/or p53 in melanomagenesis. Mice harboring melanocyte-specific activated K-Ras and loss of p16^INK4a and/or p53 developed invasive, unpigmented and nonmetastatic melanomas with short latency and high penetrance. In addition, the capacity of these somatic genetic events to rapidly induce melanomas in adult mice suggests that melanocytes remain susceptible to transformation throughout adulthood.

Self-regulation in the modification of disruptive classroom behavior

This study compared self-regulation and external regulation procedures in the treatment of children's disruptive classroom behavior. After baseline data were collected, three of the four most disruptive children in each of 10 first- and second-grade classrooms received reinforcement for achieving low rates of disruptive behavior. The fourth child served as a control subject throughout the experiment. Two of the three experimental subjects were then taught to self-observe their own disruptive behavior. In the final reinforcement period, these subjects were given control over dispensing reinforcers to themselves, based on their self-collected behavioral data while subjects in the other experimental group continued with the externally managed reinforcement. In extinction, reinforcement was discontinued for all subjects, but one of the self-regulation subjects in each classroom continued overtly to self-observe. Results indicated that both reinforcement programs reduced disruptive behavior. The self-regulation procedures were slightly more effective in reducing disruptiveness than was the external regulation procedure, and this advantage persisted into extinction. These results suggest that self-regulation procedures provide a practical, inexpensive, and powerful alternative in dealing with disruptive behavior in children.

Parental manipulation of child behavior in home observations

The object of this study was to investigate the extent to which parents can manipulate their children's behavior in home observations. Twelve families with four- to six-year old children were recruited for the research. The parents were instructed to make their child look "bad" or "deviant" on three days of a six-day observation and to look "good" or "nondeviant" on alternate days. Results indicated that, as predicted, the rate of child deviant behavior, parental negative responding, and parental commands were all significantly higher on bad than good days. Parental responses to questionnaires provided more detailed information on how parents felt that they influenced their children in the desired directions. These results were discussed in terms of their implications for child psychopathology and the methodology of data collection in the natural environment.

Timeout duration and the suppression of deviant behavior in children

The effects of three different timeout durations were investigated in a group of 20 retarded, institutionalized subjects. Each subject received 1, 15, and 30 min of timeout in a design that was counterbalanced in terms of the order in which timeout durations were presented. Displays of deviant behavior-such as aggression, tantrums, and self-destruction-were followed by periods of isolation in a timeout room. A reversal design was employed such that return-to-baseline periods were instituted after each timeout period. The overall effect of timeout was to reduce significantly the rate of deviant behavior. On the average, 15 and 30 min produced a 35% decrease in deviant behavior with little difference between the effectiveness of 15 and 30 min. The range of effects in all timeout conditions varied widely. The sequence in which the 1-min duration was presented effected the direction of its effect. When it preceded the use of longer durations, 1 min was most effective. As it came later in the sequence, its suppressive characteristics became less reliable.

Reactivity to home observation: a comparison of audio recorded behavior with observers present or absent

THE STUDY COMPARED THE BEHAVIOR OF FAMILY MEMBERS AT HOME AS RECORDED BY AUDIOTAPE RECORDINGS IN TWO CONDITIONS: with an observer present or absent. Behavioral differences were expected as a function of differential reactivity to these observational procedures, but none was found, and there was no evidence of adaptation effects in either condition. In general, significant positive correlations were obtained between the rates of recorded behavior in both situations. The implications of these findings for the development of nonreactive observation procedures were discussed.

Evaluation of family intervention through unobtrusive audio recordings: experiences in "bugging" children

Five children referred to a child-family intervention program wore a radio transmitter in the home during pre-intervention and termination assessments. The transmitter broadcast to a receiver-recording apparatus in the home (either activated by an interval timer at predetermined "random" times or by parents at predetermined "picked" times). "Picked" times were parent-selected situations during which problems typically occurred (e.g., bedtime). Parents activated the recorder regularly whether or not problems occurred. Child-deviant, parent-negative, and parent-commanding behaviors were significantly higher at the picked times during pretest than at random times. At posttest, behaviors in all three classes were substantially reduced at picked times, but not at random times. For individual subject data, reductions occurred in at least two of the three dependent variables for three of the five cases during random time assessments. In general, the behavioral outcome data corresponded to parent-attitude reports and parent-collected observation data.

Bicarbonate-regulated soluble adenylyl cyclase (sAC) mRNA expression and activity in peripheral chemoreceptors

Peripheral arterial chemoreceptors in the carotid body (CB) are modulated by pH/CO(2). Soluble adenylyl cyclase (sAC) is directly stimulated by bicarbonate ions (HCO(3)). Because CO(2)/HCO(3) mediates depolarization in chemoreceptors, we hypothesized that sAC mRNA would be expressed in the CB, and its expression and function would be regulated by CO(2)/HCO(3).Sprague-Dawley rats at postnatal days 16-17 were used to compare sAC mRNA gene expression between CB and non-chemosensitive tissues: superior cervical (SCG), petrosal (PG) and nodose ganglia (NG) by quantitative real time-PCR. Rat sAC gene expression was standardized to the expression of GAPDH (housekeeping gene) and the data were analyzed with the Pfaffl method. Gene and protein expression, and sAC regulation in the testis was used as a positive control. To determine the regulation of sAC mRNA expression and activity, all tissues were exposed to increasing concentrations of bicarbonate (0, 24, 44 mM, titrated with CO(2) and maintained a constant pH of 7.40).

RESULTS

sAC mRNA expression was between 2-11% of CB expression in the SCG, PG and NG. Furthermore, only in the CB did HCO(3) upregulate sAC gene expression and increase cAMP levels.

CONCLUSION

sAC mRNA and protein expression is present in peripheral arterial chemoreceptors and non-chemoreceptors. In the CB, CO(2)/HCO(3) not only activated sAC but also regulated its expression, suggesting that sAC may be involved in the regulation of cAMP levels in response to hyper/hypocapnia.

Adults with untreated phenylketonuria: out of sight, out of mind

Some people with phenylketonuria who were born before screening began were never treated and are still alive. Here we report that far fewer people with untreated phenylketonuria were detected than are thought to exist (about 2000). The majority of those traced had high support needs, challenging behaviour and other symptoms of phenylketonuria. No significant differences were found between those who had or had not tried the phenylalanine-restricted diet. A randomised controlled trial is required to examine the effect of trying the low-phenylalanine diet for people with untreated phenylketonuria.

Ecto 5'-nucleotidase deficiency in primary hypogammaglobulinaemia

The activity of the lymphocyte ectoenzyme 5'-nucleotidase is very low in the majority of patients with primary 'common variable' hypogammaglobulinaemia. In order to test whether this can be explained by lymphocyte subpopulation deficiencies we measured 5'-nucleotidase activity, using both biochemical and histochemical techniques, in purified T and B cells from patients and healthy subjects. Purified B cells from normal subjects have about four times the activity of T cells. This explains why the levels of lymphocyte 5'-nucleotidase activity are at the lower limit of the normal range in patients with X-linked hypogammaglobulinaemia who lack B cells. The low levels in the 'common variable' group can be explained by low activity in their T lymphocytes associated with either low activity in their B cells or depletion of B cells. The finding that inhibition of the enzyme does not interfere with in vitro lymphocyte transformation or immunoglobulin production in normal subjects indicates that the enzyme deficiency is not directly responsible for the hypogammaglobulinaemia. These and other studies suggest that this enzyme appears on lymphocytes at a certain stage of development and that both T and B lymphocytes in some patients with 'common variable' hypogammaglobulinaemia are developmentally immature.

Multilayer PDMS microfluidic chamber for controlling brain slice microenvironment

A novel three-layer microfluidic polydimethylsiloxane (PDMS) device was constructed with two fluid chambers that holds a brain slice in place with microposts while maintaining laminar perfusate flow above and below the slice. Our fabrication technique permits rapid production of PDMS layers that can be applied to brain slices of different shapes and sizes. In this study, the device was designed to fit the shape and thickness (530-700 microm) of a medullary brain slice taken from P0-P4 neonatal rats. Medullary slices in this chamber spontaneously produced rhythmic, respiratory-related motor output for up to 3 h, thereby demonstrating that brain slice viability was maintained for prolonged periods. This design is unique in that it achieves independent control of fluids through multiple channels in two separate fluid chambers. The laminar flow exhibited by the microfluidic chamber allows controlled solutions to target specific areas of the brain slice based on the input flow rates. To demonstrate this capability, a stream of Na(+)-free solution was focused on one half of a medullary slice to abolish spontaneous neural activity in only that half of the brain slice, while the other half remained active. We also demonstrated that flow of different solutions can be focused over the midline of the brain slice. The multilayer brain slice chamber design can integrate several traditional types of electrophysiology tools that are commonly used to measure neurophysiological properties of brain slices. Thus, this new microfluidic chamber is advantageous for experiments that involve controlled drug or solution delivery at high spatiotemporal resolution.

Serotonin-induced in vitro long-term facilitation exhibits differential pattern sensitivity in cervical and thoracic inspiratory motor output

Intermittent hypoxia induces 5-HT-dependent, pattern-sensitive long-term facilitation (LTF) of spinal respiratory motor output. We used a split-bath in vitro neonatal rat brainstem-spinal cord preparation to test whether: 1) intermittent spinal 5-HT exposure (without hypoxia) is sufficient to induce LTF in phrenic and intercostal inspiratory motor outputs; 2) LTF magnitude is greater in intercostal versus phrenic activity; and 3) phrenic and intercostal motor output exhibits differential pattern sensitivity to 5-HT application. With a barrier at spinal segment C1, 5-HT (5 muM) was applied episodically (3 min 5-HT, 5 min wash, x3) to the spinal cord (C2-L1) while recording inspiratory bursts in cervical (C4 or C5) and thoracic (T5 or T6) ventral roots. Episodic 5-HT application increased cervical and thoracic burst amplitudes to 136+/-22% and 150+/-22% of baseline, respectively, at 120 min post-drug (P<0.01). Continuous 5-HT application (5 muM, 9 min) had no effect on cervical burst amplitude at 120 min post-drug, but increased thoracic burst amplitude to 142+/-11% of baseline at 120 min post-drug (P<0.001). Methysergide pretreatment abolished both cervical and thoracic 5-HT-induced LTF. Quantitative reverse transcriptase-polymerase chain reaction and immunocytochemistry revealed that 5-HT(2A) and 5-HT(7) receptor subtypes (receptors known to influence LTF expression in adult rats) are expressed in ventral cervical and thoracic spinal cord with no differences in expression levels due to spinal segment or age. Thus, 5-HT is sufficient to induce spinal LTF in neonatal rats and differences in pattern sensitivity suggest heterogeneity in underlying mechanisms.

Influence of oestradiol and tamoxifen on oestrogen receptors-alpha and -beta protein degradation and non-genomic signalling pathways in uterine and breast carcinoma cells

Tamoxifen acts as an oestrogen antagonist in the breast reducing cell proliferation, but in the uterus as an oestrogen agonist resulting in increased cell proliferation. Tamoxifen exerts its tissue-specific effects through the oestrogen receptors (ERalpha or ERbeta). The levels and functions of the two ERs affect the response of the target tissue to oestrogen and tamoxifen. We examined the control of ER stability in breast and uterine cell lines using western blotting and RT-PCR. In MCF-7 breast-derived cells, ERalpha and ERbeta proteins were rapidly degraded via the proteasome pathway in response to oestradiol; conversely tamoxifen stabilised both receptors. In Ishikawa uterine-derived cells, oestradiol and tamoxifen stabilised ERalpha but led to degradation of ERbeta by the proteasome pathway. Further investigations showed that oestradiol induced activation of the non-genomic ERalpha/Akt signalling pathway in MCF-7 cells. We have demonstrated that the alternative Erk signalling pathway is activated in Ishikawa cells following oestradiol treatment in the absence of an active proteasome pathway and therefore increased levels of ERbeta. In conclusion, our data have demonstrated tamoxifen or oestradiol control of ER subtype stability and that non-genomic activation of transcription pathways is cell specific.

Time-dependent changes in spontaneous respiratory activity in turtle brainstems in vitro

Our goal was to determine whether time-dependent changes in respiratory motor output in vitro could be minimized by altering bath solution composition. Adult turtle brainstems were bathed in standard solution, nutrient-rich Dulbecco's Eagle media (100 or 25% concentration), or standard solution with phenylbiguanide (PBG, 5-HT3 agonist which increases respiratory drive). Except for a 63% frequency increase in PBG solution, hypoglossal bursts were unaltered within 100 min of observation. Respiratory activity was abolished within 7 h in 100% Dulbecco's compared with a mean of 24-31 h in other test solutions. At 12 h, burst frequency decreased faster in standard solution and 25% Dulbecco's (-0.28+/-0.07 and -0.13+/-0.05 bursts/h, respectively) compared with PBG solution (-0.09+/-0.04 bursts/h); amplitude declined at approximately 2%/h in all solutions. The tendency for episodic discharge decreased gradually in standard solution, but was eliminated in 25% Dulbecco's and PBG solution. Certain bath solutions may minimize time-dependent frequency reductions but may also cause breathing pattern changes.

Assessment of analysis by gender in the Cochrane reviews as related to treatment of cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD) is the leading killer of women in the United States, yet medical care is often based on evidence from clinical trials performed predominantly with men. Numerous studies show that CVD risk factors, clinical presentation, treatment, and treatment outcomes can vary between men and women.

METHODS

The Cochrane Library maintains a large database of critically appraised evidence including meta-analyses of clinical trials, called Systematic Reviews. There were 30 Systematic Reviews pertaining to the treatment of CVD published collectively by the Cochrane Heart Group, Hypertension Group, and Peripheral Vascular Diseases Groups at the time of our study. We examined these 30 Systematic Reviews and the great majority of the clinical trials used for their meta-analyses for inclusion of women and gender-based data analyses. Women comprised only 27% of the pooled population of 258 clinical trials.

RESULTS

Of those trials that included both men and women (n = 196), only 33% examined outcomes by gender. In trials that performed a gender-based analysis, 20% reported significant (p < 0.05) differences in cardiovascular-related outcomes by gender.

CONCLUSIONS

We conclude that (1) there are not enough large-scale clinical trials or meta-analyses concerning CVD in women to determine if their medical treatment should differ from that of men, (2) all clinical trials relating to CVD treatment should have significantly more female participants, and gender-based analyses should be performed, as currently recommended for National Institutes of Health (NIH)-sponsored research by the NIH Revitalization Act of 1993, and (3) the Cochrane Library would be a more useful tool for the evidence-based healthcare of women if the Systematic Reviews used all available gender-specific information in their analyses.

Biphasic superoxide generation in potato tubers. A self-amplifying response to stress

Potato (Solanum tuberosum) cultivars differ quantitatively in their responses to mechanical stress including the ability to synthesize melanin pigments in tuber tissues. Investigations into the cellular events induced by mechanical stress on tuber tissues have shown that an early cellular response is a significant and rapid synthesis of superoxide radicals. This burst of radical production distinctively displays a reproducible biphasic pattern over time with peaks of generation at 2 and 5 h. A concomitant consequence of the generation of these free radicals is elevated levels of oxidatively modified tuber proteins. Both radical generation and protein modification vary between cultivars but both are directly proportional to the amount of melanin pigments produced. Cell-free extracts of mechanically stressed tissues, pectic fragments, and scission products generated from cell walls are able to induce superoxide generation in non-stressed tissues, indicating the participation of a biologically active factor that induces a further a phase of radical synthesis.

Avalanche trauma and closed head injury: adding insult to injury

OBJECTIVE

The incidence of fatal closed head injury (CHI) and nonfatal CHI causing an altered level of consciousness in avalanche victims is unknown. The purpose of this study was to assess the incidence and potential significance of CHI in avalanche-related deaths.

METHODS

The records of the state medical examiner and hospital records of all victims killed in avalanches in the state of Utah from October 1, 1992 through April 30, 1999 were reviewed for a cause of death and for the presence of CHI. Closed head injury was described as "present" or "severe," depending on whether the degree of CHI was sufficient to have caused or directly contributed to death, as determined by the medical examiner.

RESULTS

In this review, 28 avalanche-related deaths were identified, of which 22 (79%) were due to asphyxia. Seventeen victims (61%) had evidence of some degree of CHI. Six victims (21%) had evidence of severe CHI. One of 7 snowmobile riders sustained a severe CHI, whereas 4 of 16 skiers or snowboarders sustained a severe CHI (P = not significant).

CONCLUSION

Although asphyxiation was the cause of death in most avalanche victims, evidence of CHI was present in 61% of the cases studied. While avalanche-associated CHI may not be sufficient to cause death in many cases, a depressed level of consciousness might render a victim incapable of self-rescue and predispose to asphyxia. Helmet use may help prevent avalanche-associated CHI and thus be a useful safety adjunct.

Serotonin elicits long-lasting enhancement of rhythmic respiratory activity in turtle brain stems in vitro

Brain stem preparations from adult turtles were used to determine how bath-applied serotonin (5-HT) alters respiration-related hypoglossal activity in a mature vertebrate. 5-HT (5-20 microM) reversibly decreased integrated burst amplitude by approximately 45% (P < 0.05); burst frequency decreased in a dose-dependent manner with 20 microM abolishing bursts in 9 of 13 preparations (P < 0.05). These 5-HT-dependent effects were mimicked by application of a 5-HT(1A) agonist, but not a 5-HT(1B) agonist, and were abolished by the broad-spectrum 5-HT antagonist, methiothepin. During 5-HT (20 microM) washout, frequency rebounded to levels above the original baseline for 40 min (P < 0.05) and remained above baseline for 2 h. A 5-HT(3) antagonist (tropesitron) blocked the post-5-HT rebound and persistent frequency increase. A 5-HT(3) agonist (phenylbiguanide) increased frequency during and after bath application (P < 0.05). When phenylbiguanide was applied to the brain stem of brain stem/spinal cord preparations, there was a persistent frequency increase (P < 0.05), but neither spinal-expiratory nor -inspiratory burst amplitude were altered. The 5-HT(3) receptor-dependent persistent frequency increase represents a unique model of plasticity in vertebrate rhythm generation.

Catecholamine neuron groups in rat brain slices differ in their susceptibility to excitatory amino acid induced dendritic degeneration

We investigated whether specific types of catecholamine neurons were differentially vulnerable to damage induced by excitatory amino acids (EAAs) in vitro in a rat brain slice preparation. Brain slices, 300 micro m thick, were cut horizontally, exposed to either N-methyl-D-aspartate (NMDA) or kainic acid (KA) for 2h, fixed and then cut into thin (30 micro m) sections in the same (horizontal) plane as the slice. The sections were immunolabelled for tyrosine hydroxylase to identify different groups of catecholamine neurons (substantia nigra (SN), paranigral (PN), interfascicular (IF) and hypothalamic A11, A13 and A14) which exhibited prominent dendritic projections in the horizontal plane. Loss of dendrites was used as a sensitive index of damage that precedes the loss of the cell body. Catecholamine neurons differed strikingly in their vulnerability of EAA-induced dendrite degeneration. The most vulnerable were those in the dorsal tier of the SN, whereas the most resistant were those in the hypothalamic A11 group. For example, in the dorsal tier of SN, NMDA (50 micro M) reduced the proportion of neurons with dendrites from 64% (+/- 8% SEM) in controls to 13% (+/- 7%) whereas the majority of A11 neurons (69 +/- 10%) retained their dendrites compared to controls (89% +/- 8%). The other groups of catecholamine neurons exhibited intermediate vulnerability. An essentially similar pattern of differential vulnerability was observed with KA. An understanding of the cellular mechanisms that underlie the particular vulnerability of SN neurons in the slice will aid the discovery of pharmacological therapies to prevent or slow the pathological process in neurodegenerative diseases which involve these neurons.

Plasticity in respiratory motor control: intermittent hypoxia and hypercapnia activate opposing serotonergic and noradrenergic modulatory systems

Experimental results consistently show that the respiratory control system is plastic, such that environmental factors and experience can modify its performance. Such plasticity may represent basic neurobiological principles of learning and memory, whereby intermittent sensory stimulation produces long-term alterations (i.e. facilitation or depression) in synaptic transmission depending on the timing and intensity of the stimulation. In this review, we propose that intermittent chemosensory stimulation produces long-term changes in respiratory motor output via specific neuromodulatory systems. This concept is based on recent data suggesting that intermittent hypoxia produces a net long-term facilitation of respiratory output via the serotonergic system, whereas intermittent hypercapnia produces a net long-term depression by a mechanism associated with the noradrenergic system. There is suggestive evidence that, although both respiratory stimuli activate both modulatory systems, the balance is different. Thus, these opposing modulatory influences on respiratory motor control may provide a 'push-pull' system, preventing unchecked and inappropriate fluctuations in ventilatory drive.

Inherited thrombophilia: a possible cause of in utero vascular thrombosis in children with intestinal atresia

BACKGROUND

Congenital atresia of the small and large intestine is thought to evolve from in utero mesenteric vascular occlusion of the corresponding intestinal segment. Because spontaneous thrombosis recently has been described in association with inherited thrombophilia, the authors wondered if inherited thrombophilia also might be found in babies with intestinal atresia.

METHODS

Genetic analysis was done on 28 children treated for congenital intestinal atresia. DNA was analyzed for point mutations to detect the 2 most common types of inherited thrombophilia, the G1691A mutation in the factor V gene (factor V Leiden) and the G20210A mutation in the prothrombin gene. In addition, other genetic risk factors for thrombosis were analyzed including the C677T mutation in the methylenetetrahydrofolate reductase gene (MTHFR) and 2 polymorphisms of the factor VII gene (the R353Q and the hypervariable region 4 polymorphisms).

RESULTS

The factor V Leiden mutation was present in 5 of 28 (18%) children treated for congenital intestinal atresia. This is increased significantly when compared with the reported carrier frequency of 3% to 7% in the general population and a reported carrier rate of 4.2% in the local population (P <.005). The R353Q polymorphism of the factor VII gene, specifically the RR genotype, was noted in 85% of patients with atresia with an expected frequency of 64% (P <.008). There were no significant associations noted between mutations in the prothrombin gene, the MTHFR gene, or the hypervariable region of the factor VII gene.

CONCLUSIONS

The factor V Leiden mutation and the RR subtype of the R353Q polymorphism of the factor VII gene are seen at an increased frequency in children with congenital intestinal atresia. This suggests that inherited thrombophilia may play a role in the etiology of these in utero mesenteric thrombotic events.

Diminished use of osteopathic manipulative treatment and its impact on the uniqueness of the osteopathic profession

PURPOSE

To determine whether osteopathic manipulative treatment (OMT), a key identifiable feature of osteopathic medicine, is becoming a "lost art" in the profession, and whether the long-term evolution of osteopathic medicine into mainstream medicine and particularly specialization has had a similar impact on the use of OMT by family practitioners and specialists.

METHOD

In April 1998, a two-page questionnaire was mailed to 3,000 randomly selected osteopathic physicians in the United States to assess factors affecting their use of OMT. Descriptive statistics, linear regression analyses, and analysis of variance techniques were used to test for differences.

RESULTS

The response rate was 33.2%. Over 50% of the responding osteopathic physicians used OMT on less than 5% of their patients, and analysis of variance revealed OMT use was significantly affected by practice type, graduation date, and family physicians versus specialists. For specialists, 58% of the variance regression was attributed to barriers to use, practice protocol, attitudes, and training, whereas for family physicians, 43% of the variance regression was attributed to barriers to use, practice protocol, and attitudes. More important, the eventual level of OMT use was related to whether postgraduate training had been undertaken in osteopathic, allopathic, or mixed staff facilities, particularly for osteopathic specialists.

CONCLUSIONS

The evidence supports the assertion that OMT is becoming a lost art among osteopathic practitioners. Osteopathic as well as allopathic medical educators and policymakers should address the impact of the diminished use of OMT on both U.S. health care and the unique identifying practices associated with the osteopathic profession.

Assessment of the human cellular immune response to T27K, a coccidioidal antigen preparation, by flow cytometry of whole blood

Whole blood flow cytometry was performed among donors with various clinical forms of coccidioidomycosis using T27K, a coccidioidal antigen preparation protective in mice but not previously studied in humans. The median percent of CD3+ lymphocytes (CD3+) producing intracellular interferon-gamma (IFN-gamma) among healthy immune donors was 0.43%, significantly above that for non-immune donors (0.01%) and greater than that for subjects with other forms of coccidioidomycosis, including chronic pulmonary (0.11%), disseminated (0.09%) and concomitant human immunodeficiency virus (HIV) infection (0.07%) (P < or =0.002 for all). No increase in intracellular interleukin (IL)-10 production or apoptosis was noted in samples incubated with T27K. Among 14 HIV-infected patients with concomitant coccidioidomycosis, seven of eight patients whose peripheral blood CD4 concentration was > 200 cells microl(-1) had > 0.06% of CD3+ produce intracellular IFN-gamma, compared to none of six whose peripheral blood CD4+ lymphocyte concentration was < or =200 cells microl(-1) (P = 0.005). These data indicate that there is a specific human cellular immune response to T27K as a coccidioidal antigen and that this response can be categorized based on the clinical status of the coccidioidally infected patient.

Models of respiratory rhythm generation in the pre-Bötzinger complex. III. Experimental tests of model predictions

We used the testable predictions of mathematical models proposed by Butera et al. to evaluate cellular, synaptic, and population-level components of the hypothesis that respiratory rhythm in mammals is generated in vitro in the pre-Bötzinger complex (pre-BötC) by a heterogeneous population of pacemaker neurons coupled by fast excitatory synapses. We prepared thin brain stem slices from neonatal rats that capture the pre-BötC and maintain inspiratory-related motor activity in vitro. We recorded pacemaker neurons extracellularly and found: intrinsic bursting behavior that did not depend on Ca(2+) currents and persisted after blocking synaptic transmission; multistate behavior with transitions from quiescence to bursting and tonic spiking states as cellular excitability was increased via extracellular K(+) concentration ([K(+)](o)); a monotonic increase in burst frequency and decrease in burst duration with increasing [K(+)](o); heterogeneity among different cells sampled; and an increase in inspiratory burst duration and decrease in burst frequency by excitatory synaptic coupling in the respiratory network. These data affirm the basis for the network model, which is composed of heterogeneous pacemaker cells having a voltage-dependent burst-generating mechanism dominated by persistent Na(+) current (I(NaP)) and excitatory synaptic coupling that synchronizes cell activity. We investigated population-level activity in the pre-BötC using local "macropatch" recordings and confirmed these model predictions: pre-BötC activity preceded respiratory-related motor output by 100-400 ms, consistent with a heterogeneous pacemaker-cell population generating inspiratory rhythm in the pre-BötC; pre-BötC population burst amplitude decreased monotonically with increasing [K(+)](o) (while frequency increased), which can be attributed to pacemaker cell properties; and burst amplitude fluctuated from cycle to cycle after decreasing bilateral synaptic coupling surgically as predicted from stability analyses of the model. We conclude that the pacemaker cell and network models explain features of inspiratory rhythm generation in vitro.

Perceived risks and reported behaviors associated with osteoporosis and its treatment

This study investigates older American women's knowledge and risk perceptions about osteoporosis and its treatment. Our results indicate that older U.S. women undervalue the health impact of osteoporosis; they consider it controllable, and neither life threatening nor dreaded relative to other possible diseases or conditions. At least 1/3 of older women in a diagnosed and general sample also confused osteoporosis with arthritis. Women scored highest on osteoporosis knowledge questions related to items under their personal control, such as diet or exercise. Further, women who understood the effects of a particular behavior on osteoporosis were more likely to act in accordance with that knowledge than were women who did not understand those effects.

Sources of information on the health effects of environmental tobacco smoke among African-American children and adolescents

PURPOSE

To determine the common sources of information regarding the effects of smoking on health and their relationship to knowledge, attitudes, and preventative efforts regarding exposure to environmental tobacco smoke (ETS) among urban African-American children and adolescents.

METHODS

All students who were enrolled in Grades 5-12 in an urban public school district located in the greater metropolitan area of Detroit, Michigan were surveyed using a structured, written questionnaire that assessed sources of information on the health effects of smoking, as well as knowledge, attitudes, and preventive efforts with respect to exposure to ETS. The primary analytic procedures utilized in the study were correlation analysis and analysis of variance.

RESULTS

The African-American students surveyed in this study received information regarding the health effects of smoking from many sources, most notably television, family, and teachers. Second, students who received information on the effects of smoking on health from family and external sources (teacher, parent's friend, and religious leader) had higher overall knowledge, attitude, and preventive efforts scores than students who received information from other sources (friends, electronic media, and printed media). Finally, family influence was greater when parents were not smokers, and influenced elementary students more than middle school or high school students.

CONCLUSIONS

The active involvement of teachers, religious leaders, parents, and other influential adults should be elicited in tobacco education and prevention efforts to maximize their effectiveness.

Intralesional injection of mumps or Candida skin test antigens: a novel immunotherapy for warts

BACKGROUND

Warts are common and induce physical and emotional discomfort. Numerous therapies exist, yet none is optimal. Despite theoretical advantages, immunotherapeutic modalities are often neglected as first-line wart therapies.

OBJECTIVE

To compare treatment with intralesional skin test antigen injection of 1 wart vs cryotherapy of all warts.

DESIGN

Pilot study.

SETTING

University dermatology outpatient clinic.

PATIENTS

A total of 115 consecutive patients with at least 1 nongenital wart.

INTERVENTIONS

Patients with warts were tested for immunity to mumps and Candida using commercial antigens. Nonresponders received cryotherapy and immune individuals received cryotherapy or intralesional injection of 1 antiserum.

RESULTS

Thirty-four (30%) of the 115 patients did not respond to the test injections and 81 (70%) had detectable immunity. Of the immune group, 26 (32%) received cryotherapy, 45 (56%) received intralesional mumps antiserum, and 10 (12%) received intralesional Candida antiserum. Of the anergic patients, 28 (82%) were treated with cryotherapy; 6 (18%) refused cryotherapy. Of the 39 patients who were treated with immunotherapy and completed the protocol, 29 (74%) had complete clearing of the treated wart. Fourteen (78%) of 18 patients with complete resolution of their immunotherapy-treated wart also had resolution of untreated, distant warts.

CONCLUSIONS

Intralesional injection of mumps or Candida antigens into warts of immune individuals represents effective treatment. Observation of clearing of anatomically distinct and distant warts suggests acquisition of human papillomavirus-directed immunity in some patients. We conclude that this novel approach to immunotherapy may serve as first-line treatment in immune individuals with multiple or large warts and as second-line treatment in immune patients for whom cryotherapy fails.

Attachment injuries in couple relationships: a new perspective on impasses in couples therapy

This article identifies and operationalizes the newly defined construct of attachment injury. An attachment injury occurs when one partner violates the expectation that the other will offer comfort and caring in times of danger or distress. This incident becomes a clinically recurring theme and creates an impasse that blocks relationship repair in couples therapy. An attachment injury is characterized by an abandonment or by a betrayal of trust during a critical moment of need. The injurious incident defines the relationship as insecure and maintains relationship distress because it is continually used as a standard for the dependability of the offending partner. The concept of an attachment injury is defined here in the context of emotionally focused therapy, an empirically validated, short-term approach to modifying distress in couples. The broad theoretical underpinnings of this concept may be found in attachment theory as applied to adult romantic relationships. Through the delineation of attachment injury events and the ongoing development of a detailed model of resolution, couples therapists will be better able to identify, describe, and effectively treat such injuries and address the therapeutic impasses that are associated with them.

Yellow eyelids heralding lymphoma

Yellow eyelids are an uncommon finding but can be cosmetically disfiguring to a patient. There are a variety of causes of yellow eyelids. A case study as well as the differential diagnosis of yellow eyelids are presented.

Isolation of the kernel for respiratory rhythm generation in a novel preparation: the pre-Bötzinger complex "island"

The pre-Bötzinger complex (pre-BötC), a bilaterally distributed network of rhythmogenic neurons within the ventrolateral medulla, has been proposed to be the critical locus for respiratory rhythm generation in mammals. To date, thin transverse medullary slice preparations that capture the pre-BötC have served as the optimal experimental model to study the region's inherent cellular and network properties. We have reduced the thin slices to isolated pre-BötC "islands" to further establish whether the pre-BötC has intrinsic rhythmicity and is the kernel for rhythmogenesis in the slice. We recorded neuron population activity locally in the pre-BötC with macroelectrodes and fluorescent imaging of Ca(2+) activities with Calcium Green-1AM dye before and after excising the island. The isolated island remained rhythmically active with a population burst profile similar to the inspiratory burst in the slice. Rhythmic population activity persisted in islands after block of GABA(A)ergic and glycinergic synaptic inhibition. The loci of pre-BötC Ca(2+) activity imaged in thin slices and islands were similar, and imaged pre-BötC neurons exhibited synchronized flashing after blocking synaptic inhibition. Population burst frequency increased monotonically as extracellular potassium concentration was elevated, consistent with mathematical models consisting entirely of an excitatory network of synaptically coupled pacemaker neurons with heterogeneous, voltage-dependent bursting properties. Our results provide further evidence for a rhythmogenic kernel in the pre-BötC in vitro and demonstrate that the islands are ideal preparations for studying the kernel's intrinsic properties.

Management of glaucoma in pregnancy and lactation

A 30-year-old pregnant woman with glaucoma is presented. The management of her case is used as a basis for a discussion of the use of glaucoma medications, including newer formulations, during pregnancy and lactation.

Hepatic lipase overexpression lowers remnant and LDL levels by a noncatalytic mechanism in LDL receptor-deficient mice

To address the role of the noncatalytic ligand function of hepatic lipase (HL) in low density lipoprotein (LDL) receptor-mediated lipoprotein metabolism, we characterized transgenic mice lacking the LDL receptor (LDLR) that express either catalytically active (Ldlr(-/-)HL) or inactive (Ldlr(-/-)HL(S145G)) human HL on both chow and high fat diets and compared them with nontransgenic Ldlr(-/-) mice. In mice fed a chow diet, apolipoprotein (apo)B-containing lipoprotein levels were 40-60% lower in Ldlr(-/-)HL and Ldlr(-/-)HL(S145G) mice than in Ldlr(-/-) mice. This decrease was mainly reflected by decreased apoB-48 levels in the Ldlr(-/-)HL mice and by decreased apoB-100 levels in Ldlr(-/-) HL(S145G) mice. These findings indicate that HL can reduce apoB-100-containing lipoproteins through a noncatalytic ligand activity that is independent of the LDLR. Cholesterol enrichment of the apoB-containing lipoproteins induced by feeding Ldlr(-/-)HL and Ldlr(-/-)HL(S145G) mice a cholesterol-enriched high fat (Western) diet resulted in parallel decreases in both apoB-100 and apoB-48 levels, indicating that HL is particularly efficient at reducing cholesterol-enriched apoB-containing lipoproteins through both catalytic and noncatalytic mechanisms. These data suggest that the noncatalytic function of HL provides an alternate clearance pathway for apoB-100- and apoB-48-containing lipoproteins that is independent of the LDLR and that contributes to the clearance of high density lipoproteins.

Acute methionine loading does not alter arterial stiffness in humans

Hyperhomocystinemia is a risk factor for cardiovascular disease, and acute elevation of plasma homocysteine after methionine loading impairs endothelial function in healthy subjects. Interestingly, pretreatment with vitamin C can ameliorate this effect. We have already shown that acute oral vitamin C administration reduces arterial stiffness in healthy subjects, and the aim of the present study was to investigate the effect of methionine loading on arterial stiffness with and without concomitant vitamin C using the noninvasive technique of pulse wave analysis. Eight healthy male subjects (mean age, 29 years; range, 20-42 years) were studied on three occasions at weekly intervals. In a double-blind, double-dummy, randomized order they received orally either 100 mg/kg methionine, 100 mg/kg methionine plus 2 g of vitamin C, or matching placebos. Peripheral and central blood pressure, heart rate, cardiac index, arterial stiffness, and plasma homocysteine levels were assessed at baseline and 6 hours after dosing. Compared with placebo, there was no significant change in any of the hemodynamic parameters, including arterial stiffness, after oral methionine, although plasma homocysteine did increase from 11.5 +/- 1.6 to 28.7 +/- 4.4 microM (mean +/- SEM; p < 0.001). Combined methionine and vitamin C led to a similar increase in plasma homocysteine but significantly reduced augmentation index by 10.5 +/- 3.2% (p = 0.02). Acute hyperhomocystinemia does not significantly alter arterial stiffness, as assessed by pulse wave analysis, whereas a combination of methionine and vitamin C leads to a similar reduction in augmentation index to that previously described after vitamin C alone. These data reinforce evidence that vitamin C reduces arterial stiffness but do not indicate any important interaction with oral methionine.

Expression of oestrogen receptor alpha variants in non-malignant breast and early invasive breast carcinomas

Oestrogen receptor (ER) alpha variants have been described in normal breast and breast carcinomas, but their presence in a range of benign conditions and in small early invasive breast carcinomas has not been considered. Cryostat tissue sections from 19 normal and proliferative breast lesions and 44 carcinomas 15 mm and less in size detected by mammographic screening were screened for ERalpha splice variants using reverse transcriptase-nested PCR. The carcinomas were assessed for mutation by single-stranded conformational polymorphism analysis and variant forms/band shifts were sequenced. ERalpha was detected in all 19 non-malignant cases and exon 7-deleted variants were found in 16 of them. Three cases showed weak expression of exon 5, and two of exon 3 variants. There was no relationship between the presence of variants and the extent of proliferative change, ER status or age. ERalpha mRNA was not detected in two carcinomas; exon 3 deletions were found in four (9. 5%) of the other carcinomas, exon 5 in two (4.8%), and exon 7 in 11 (26.2%), with two variants in four carcinomas and a total of 29.5% of all cases having detectable variants. Two point mutations were found in one, which was a tubular carcinoma. Variant forms were identified in carcinomas of all sizes (bar<10 mm) but were more frequent in those of 15 mm. There was no relationship with type, grade or receptor status. The main difference between non-malignant breast and early invasive cancers related to exons 3 and 5. The findings suggest that ERalpha variants are not involved in breast cancer development but occur with tumour progression and may be a consequence rather than a cause.

Respiratory rhythm generation in neonatal and adult mammals: the hybrid pacemaker-network model

We review a new unified model of respiratory rhythm generation - the hybrid pacemaker-network model. This model represents a comprehensive synthesis of cellular and network mechanisms that can theoretically account for rhythm generation in different functional states, from the most reduced states in the neonatal nervous system in vitro to the intact adult system in vivo. The model incorporates a critical neuronal kernel consisting of a network of excitatory neurons with state-dependent, oscillatory bursting or pacemaker properties. This kernel, located in the pre-Bötzinger complex of the ventrolateral medulla, provides a rudimentary pacemaker network mechanism for generating an inspiratory rhythm, revealed predominately in functionally reduced states in vitro. In vivo the kernel is embedded in a larger network that interacts with the kernel via inhibitory synaptic connections that provide the dynamic control required for the evolution of the complete pattern of inspiratory and expiratory network activity. The resulting hybrid of cellular pacemaker and network properties functionally endows the system with multiple mechanisms of rhythm generation. New biophysically realistic mathematical models of the hybrid pacemaker-network have been developed that illustrate these concepts and provide a computational framework for investigating interactions of cellular and network processes that must be analyzed to understand rhythm generation.

Activity-dependent plasticity of descending synaptic inputs to spinal motoneurons in an in vitro turtle brainstem-spinal cord preparation

An in vitro brainstem-spinal cord preparation from adult turtles was used to test the hypothesis that descending synaptic inputs to multifunctional spinal motoneurons (i.e., involved in respiration and locomotion) express activity-dependent depression or potentiation. The tissue was placed in a chamber that allowed for separate superfusion of the brainstem, spinal segments C(2)-C(4), and C(5)-D(1). Action potential conduction between the brainstem and spinal segments C(5)-D(1) was blocked by superfusing C(2)-C(4) with Na(+)-free solution. With C(5)-D(1) at [K(+)] = 10 mM, electrical stimulation at C(5) every 2 min evoked potentials in intact pectoralis (expiratory, inward rotation of shoulder) and serratus (inspiratory, outward rotation of shoulder) nerves that were stable for at least 2 hr. Application of conditioning stimulation (900 pulses at 1 or 10 Hz) at C(5) decreased pectoralis evoked potential amplitudes by approximately 40% initially and by 20% after 90 min; serratus evoked potentials were unaltered. Conditioning stimulation (100 Hz, 900 pulses) transiently depressed pectoralis evoked potential amplitude by <20% but produced a delayed 72% increase in serratus evoked potential amplitude after approximately 80 min. Conditioning stimulation (10 Hz) at C(5) also reduced the amplitude of sensory afferent evoked potentials in pectoralis produced by stimulating ipsilateral dorsal roots at C(8). Thus, long-lasting changes in descending synaptic inputs to multifunctional spinal motoneurons were frequency-dependent and heterosynaptic. We hypothesize that activity-dependent plasticity may modulate descending synaptic drive to spinal motoneurons involved in both respiration and locomotion.