Retrospective study found that outpatient care for infants exposed to drugs during pregnancy was sustainable and safe

AIM

We determined the safety, feasibility and sustainability of an outpatient model of care for infants exposed to intra-uterine drugs.

METHODS

This was a retrospective chart review of 774 drug-exposed infants born between 1998 and 2016 at the Royal Hospital for Women, Sydney, Australia.

RESULTS

Most (86%) of the mothers used multiple drugs, including opioids (58%). More than three-quarters (78%) of the infants were born full term at a mean gestation of 38 weeks and hospitalised for a median of seven days. This rose to 14 days if they were medicated for neonatal abstinence syndrome (NAS). Most of the NAS patients (83%) were discharged on medication, namely morphine, and the median duration of NAS treatment was 76 (interquartile range 35-120). Three medication errors occurred: two extra doses of phenobarbitone and one infant weaned off morphine faster than prescribed. No infants were rehospitalised for NAS. Four died from sudden infant death syndrome at 2.2-5.8 months after discharge and one drowned at 15 months. None were medicated at the time of death.

CONCLUSION

Outpatient care for drug-exposed infants was sustainable and had low complication rates, even for those with NAS. The optimum duration of follow-up and impact on hospital costs should be examined.

Molecular characterization of bacterial colonization in the preterm and term infant's intestine

OBJECTIVE

To further define patterns of colonising intestinal microflora in newborn infants utilising molecular methods.

METHODS

Ten term and 5 preterm (<32 wk) infants born at the Royal Hospital for Women, Sydney, Australia were enrolled in the present study and followed for 6 mo post partum. Serial stools were collected, DNA was extracted and subjected to PCR-Denaturing Gradient Gel Electrophoresis using a range of primers and sequencing. The effect of gestational length, feeding and delivery method was compared to the pattern of bacterial acquisition.

RESULTS

Intestinal bacterial diversity was lower in preterm compared with term infants. For term infants, bacterial DNA detection rates were not associated with feeding or delivery method, although Enterobacteria and Clostridia were commonly identified. The detection rate of Bifidobacteria was lower in preterm infants than term infants. Potential pathogens were detected in preterm infant samples.

CONCLUSIONS

Preterm infants frequently have aberrant bacterial colonization of the intestine. Further research is now required to determine if this may contribute to adverse health outcomes.

Early postnatal surge of serum Clara cell secretory protein in newborn infants

BACKGROUND

Clara cell secretory protein (CCSP) is an anti-inflammatory mediator, but its role in neonatal lung adaptation and diseases is uncertain.

OBJECTIVE

To characterize postnatal changes in serum CCSP in relation to gestation, respiratory disease (RDS) and bronchopulmonary dysplasia (BPD) in comparison with other anti-inflammatory cytokines (IL-4, -10 and -13).

METHODS

Blood was collected from 76 infants (26 of 23-29 weeks' gestation, 33 of 30-36 weeks' gestation and 17 term infants) at birth (preterm cord blood); on admission; at 12, 24 and 48 h; and on days 3-4 and 7 of life. CCSP was assayed by ELISA and cytokines by Bio-Plex.

RESULTS

Median serum CCSP in extremely and moderately preterm infants rose from a baseline of 13.6 and 15.9 to 33.4 ng/ml (p = 0.04) and 59.8 ng/ml (p = 0.03) at 12 h of age, respectively. CCSP levels were highest in term infants (80.7 ng/ml at 12 h). CCSP then decreased to 22.5 ng/ml on days 3-4 (p = 0.001). CCSP of 37 RDS infants fell to a lower baseline on days 4 and 7 than that of the 22 non-RDS preterms. The 8 infants who developed BPD had persistently low serum CCSP (12.7 ng/ml at 12 h). In contrast, early postnatal changes were not seen in IL-4, -10 and -13 levels, but low IL-10 and -13 levels were found on day 7 in BPD infants.

CONCLUSIONS

Serum CCSP levels were characterized by an early postnatal surge. This apparent gestation-influenced surge may represent an initiation of a protective cascade against postnatal lung injury during extrauterine adaptation.

Short-term outcomes of mothers and infants exposed to antenatal amphetamines

AIM

To determine the short-term outcomes of newborn infants and mothers exposed to antenatal amphetamines in the state of New South Wales and the Australian Capital Territory during 2004.

METHODS

Amphetamine exposure was determined retrospectively using ICD-10 AM morbidity code searches of hospital medical records and from records of local drug and alcohol services. Records were reviewed on site. All public hospitals (n = 101) with obstetric services were included.

RESULTS

Amphetamines were used by 200 (22.9%) of the 871 identified drug-using mothers. Most women (182, 91%) injected amphetamines intravenously. Compared with the other 669 drug users, amphetamine-using mothers were significantly more likely to use multiple classes of drugs (45.0% vs 7.8%), be subject to domestic violence (32.1% vs 17.5%), be homeless (14.8% vs 4.9%) and be involved with correctional services (19.8% vs 9.7%). The incidence of comorbid psychiatric illnesses were significantly higher (57.4% vs 41.7%) and their infants were more likely to be preterm (29.5% vs 20.4%), notified as children at risk (67.0% vs 32.8%), fostered before hospital discharge (14.5% vs 5.5%) and less likely to be breastfed (27.0% vs 41.6%).

CONCLUSIONS

Amphetamine-exposed mothers and infants in public hospitals of NSW and the ACT are at significantly higher risk of adverse social and perinatal outcomes even when compared with mothers and infants exposed to other drugs of dependency. Increased vigilance for amphetamine exposure is recommended due to a high prevalence of use, especially in Australia, as a recreational drug.

Does rural or urban residence make a difference to neonatal outcome in premature birth? A regional study in Australia

BACKGROUND

Patients living in rural areas may be at a disadvantage in accessing tertiary health care.

AIM

To test the hypothesis that very premature infants born to mothers residing in rural areas have poorer outcomes than those residing in urban areas in the state of New South Wales (NSW) and the Australian Capital Territory (ACT) despite a coordinated referral and transport system.

METHODS

"Rural" or "urban" status was based on the location of maternal residence. Perinatal characteristics, major morbidity and case mix adjusted mortality were compared between 1879 rural and 6775 urban infants <32 weeks gestational age, born in 1992-2002 and admitted to all 10 neonatal intensive care units in NSW and ACT.

RESULTS

Rural mothers were more likely to be teenaged, indigenous, and to have had a previous premature birth, prolonged ruptured membrane, and antenatal corticosteroid. Urban mothers were more likely to have had assisted conception and a caesarean section. More urban (93% v 83%) infants were born in a tertiary obstetric hospital. Infants of rural residence had a higher mortality (adjusted odds ratio (OR) 1.26, 95% confidence interval (CI) 1.07 to 1.48, p = 0.005). This trend was consistently seen in all subgroups and significantly for the tertiary hospital born population and the 30-31 weeks gestation subgroup. Regional birth data in this gestational age range also showed a higher stillbirth rate among rural infants (OR 1.20, 95% CI 1.09 to 1.32, p<0.001).

CONCLUSIONS

Premature births from rural mothers have a higher risk of stillbirth and mortality in neonatal intensive care than urban infants.

Pulmonary haemorrhage and cardiac dysfunction in a neonate with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

We report on a favourable case of MCAD deficiency (homozygous 985A > G) that presented as lethargy, poor feeding, pulmonary haemorrhage and cardiac arrest without hypoglycaemia. The cessation of intralipid and the commencement of carnitine supplementation were associated with a rapid clinical improvement.

CONCLUSION

Mild carnitine depletion and secondary impairment of long-chain fatty acid metabolism may have contributed to post-asphyxial myocardial dysfunction and ventricular arrhythmias. Metabolic disorders must be kept in mind as a differential diagnosis in acutely ill infants, but it must also be emphasized that carnitine therapy is not uniformly effective in all MCAD patients.

Octreotide in the treatment of congenital chylothorax

Congenital chylothorax is the accumulation of lymphatic fluid within the pleural space. Cases unresponsive to conservative management usually require surgery. Octreotide has been used successfully to treat post-traumatic chylothoraces in the paediatric and adult population. Its exact mode of action is uncertain but it is believed to reduce lymphatic drainage by a direct action on splanchnic lymph flow. We report a case of congenital chylothorax where surgery was avoided with the compassionate trial of the somatostatin analogue, octreotide. Treatment was associated with prompt respiratory improvement prior to cessation of pleural drainage. Further studies are required to ascertain its true value in congenital chylothorax.

Strabismus in infants of opiate-dependent mothers

AIM

At a follow-up clinic for infants of opiate-dependent mothers it was noted that more infants than expected developed strabismus. This study aimed to assess the prevalence of strabismus and the need for active strabismus surveillance in this population.

METHODS

Consecutive infants of opiate-dependent mothers born over an 18 mo period were recalled for ophthalmological assessment by an ophthalmologist and orthoptist. Those unable to attend were surveyed by telephone using a questionnaire.

RESULTS

49 (69%) of the 71 eligible infants were recalled at a mean age of 21 mo (range 6-39); 29 had a full ophthalmological examination and the remaining 20 completed the questionnaire only. Seven (14%) of the 49 recalled infants had strabismus on examination; 4 needed glasses or patching. A further seven (14%) had a history of intermittent strabismus but declined formal examination. Another child had significant hypermetropia without strabismus. The mean age at which strabismus was observed was 8.3 mo (range birth to 19 mo). The presence of strabismus was not significantly influenced by conditions at birth, maternal drug doses, family history or need for or duration of abstinence treatment.

CONCLUSION

The rate of strabismus in infants of opiate-dependent mothers was at least 10 times that in the general population. As attendance at follow-up is often poor, paediatricians should be aware of the association to encourage opportunistic assessment and ophthalmological surveillance of this population.

Attitudes of Level II obstetricians towards the care of the extremely premature infant: a national survey

OBJECTIVE

To explore the opinions of non-tertiary obstetricians towards the care and outcome of extremely premature infants.

METHODS

A structured questionnaire was mailed nationally to 232 obstetricians affiliated to maternity facilities with Level II nurseries.

RESULTS

The overall response rate was 75% (n = 174) after two mailings. This included 14 obstetricians who declined to participate. The median birthweight and gestation for active resuscitation was 500 g (350-800) and 24 weeks (22-26), respectively. Factors influencing decision to transfer were: better outcomes for infants born at perinatal centres (74%), paediatric advice (10%), personal beliefs (5%), parental wishes (4%), hospital policy (3%), legal repercussions (2.5%) and past history of infertility (2%). Obstetricians in Victoria and Western Australia (WA) would transfer at 22 weeks whilst the median gestation for transfer in other states was 24 weeks (P = 0.001). Most respondents underestimated intact and infant survival rates but WA and Victorian obstetricians were less pessimistic.

CONCLUSIONS

Most obstetricians in non-tertiary facilities who responded to our survey considered 500 g and 24 weeks to be the median birthweight and gestation for active resuscitation. This is similar to recent surveys of neonatologists and obstetricians in perinatal centres. There is significant underestimation of intact and infant survival at the extremes of prematurity when compared to available Australian data. Differences towards antenatal transfer between States may represent influences of local perinatal centres.

Decreased neutrophil apoptosis in tracheal fluids of preterm infants at risk of chronic lung disease

OBJECTIVE

To investigate the hypothesis that preterm infants who are more susceptible to lung damage have decreased neutrophil apoptosis, and to explore its relation to interleukin 10 (IL10) concentration.

DESIGN

Prospective cohort design.

PATIENTS

One hundred tracheal fluid specimens from 50 week-1 ventilated infants were examined for IL10 (by enzyme linked immunosorbent assay) and neutrophil apoptosis (by light microscopy).

RESULTS

Neutrophil apoptosis was absent or less than 0.22% (median 0%) in the 11 infants with chronic lung disease (CLD) (24-31 weeks gestation) during the first 4 days of life. This was significantly lower than that of the 20 preterm infants without CLD (27-31 weeks gestation; median 0.47%, range 0-1.25%) and 19 term infants (median 0.5%, range 0-2.25%). There was an increase in apoptosis in infants with CLD (median 0.44%, p = 0.046) during days 5-7. Few infants without CLD were intubated beyond 4 days. Median apoptosis on days 5-7 was 0.26% and 2.78% for non-CLD preterm and term infants, but differences were not significant. IL10 concentration in tracheal fluid of infants with CLD was less than 5 pg/ml. None of the infants with IL10 greater than 5 pg/ml developed CLD. The range of IL10 concentrations in tracheal fluid from infants without CLD was wide (0-938 pg/ml). There was no apparent correlation between IL10 levels and percentage neutrophil apoptosis in infants without CLD.

CONCLUSION

Preterm infants with low levels of IL10 and neutrophil apoptosis may be predisposed to disordered lung repair. Further studies into the method of disposal of senescent neutrophils within preterm lungs are required.

Decreased interleukin-10 in tracheal aspirates from preterm infants developing chronic lung disease

The inability to balance pulmonary injury with healing may predispose preterm infants to chronic lung disease (CLD). It is postulated that the production of interleukin (IL)-10, an anti-inflammatory cytokine, is gestationally influenced and that CLD-prone infants may have a reduced ability to produce IL-10.

METHODS

Tracheal fluid (TF) was collected at least twice weekly from 48 mechanically ventilated infants within the first 7 d of life while intubated.

RESULTS

A total of 87 TF specimens were obtained. None of the 11 CLD infants (24-31 wk of gestation) had TF IL-10 levels above 4 pg/ml (0/20 TF specimens), while 14 (70%) of the 20 non-CLD preterm infants (27-36 wk of gestation) had IL-10 levels above 5 pg/ml in one or more of their TF specimens (18/48 TF specimens, p < 0.001). Only the 5 term infants who were ventilated for severe lung disease had raised IL-10 levels (17 infants, 5/19 TF specimens). IL-10 levels, if detected, (range 6-938 pg/ml) tended to be higher with increasing gestation (Spearman's rho coefficient = 0.43; p = 0.003). TF IL-10 detection was not associated with hyaline membrane disease, antenatal steroids or influenced by TF sample volume. Overall IL-8 levels were wide ranging but towards the end of week 1 the levels were significantly higher in CLD infants (CLD: median 34 184 ng/ml, preterm non-CLD: median 699 ng/ml, p < 0.001, term: 2961 ng/ml, p = 0.028).

CONCLUSION

A gestationally influenced low IL-10 may predispose preterm infants to persistent pulmonary inflammation of CLD.

Facilitation of neonatal nasotracheal intubation with premedication: a randomized controlled trial

OBJECTIVES

To determine if premedication reduces the time and number of attempts by junior medical staff to achieve nasotracheal intubation in neonates. The experimental design was a non-blinded randomized controlled pilot trial. The setting was a perinatal centre in a university teaching hospital.

METHODS

Twenty infants (within the ranges of 25-40 weeks gestation, 650-3660 g and 1 h to 81 days of age) requiring semi-urgent intubation were randomized to either premedication with morphine, atropine and suxamethonium, or to awake intubation.

RESULTS

There were no significant differences between the two groups in regard to prior intubation experience of the staff or infant weight or gestation. The intubation procedure, including intervening events, to completion was significantly faster in premedicated infants (median 60 s vs 595 s; P = 0.002) who were intubated at a younger postnatal age. It took twice as many attempts to intubate a conscious infant (median 2 vs 1; P = 0.010). There was a greater decrease in heart rate from the baseline in the unpremedicated group (mean 68 b.p.m. vs 29 b.p.m.; P = 0.017), but decreases in oxygen saturation were not different. Blood was observed in the oral and nasal passages after intubation in five of the awake infants and in one of the premedicated infants.

CONCLUSIONS

The use of premedication reduces the total time and number of attempts taken to achieve successful nasotracheal intubation of neonates by junior medical staff under supervision.

A placebo-controlled trial of low-dose erythromycin to promote feed tolerance in preterm infants

The aim of this study was to assess the efficacy of erythromycin, a motilin agonist, in promoting enteral feed tolerance in preterm infants of < or = 32 wk gestation. Eligible infants were randomized to receive either low-dose (2.5 mg kg(-1) per dose 6 hourly) oral erythromycin ethylsuccinate or placebo for 10 d from the time of the first oral feed. The data from 22 erythromycin and 21 placebo infants were analysed. Birthweights (erythromycin 1,216 +/- 380 g, placebo 1,355 +/- 228 g, p = 0.25), gestation (erythromycin 28.6 +/- 2.2 wk, placebo 29.3 +/- 1.7 wk, p = 0.24) and other clinical variables were not different between the groups. Almost all infants were fed expressed breast milk. Erythromycin infants had significantly fewer episodes of large residual gastric aspirates (>30% of the previous 6 h worth of feeds) over 10 d (erythromycin 1.1 +/- 1.9, placebo 3.6 +/- 2.2 episodes, p = 0.0007). Infants in the erythromycin group achieved full oral feeds more quickly (6.0 +/- 2.3 vs 7.9 +/- 3.5 d, p = 0.04). There were no significant differences between the groups with regard to the number of days on total parenteral nutrition or to the time needed to regain birthweight. One enrolled infant from each group died of necrotizing enterocolitis.

CONCLUSION

Low-dose erythromycin promoted gastric emptying and feed tolerance in premature infants at a lower gestational age than previously reported. Increased exposure to broad-spectrum antibiotics may not be free of risk. Further studies are recommended to assess its efficacy in premature infants with established feed intolerance.

The diagnosis and management of neonatal urinary ascites

Urinary ascites in a newborn infant is unusual and most commonly indicates a disruption to the integrity of the urinary tract. The following report describes a case of urinary ascites, probably due to bladder rupture caused by umbilical artery catheterization, associated with hyponatremia, hyperkalemia and elevated serum creatinine. This unusual biochemical profile is characteristic of urinary 'autodialysis' and was corrected by bladder drainage.

Coordinated outpatient care of the narcotic-dependent infant

OBJECTIVE

Concern regarding parental capacity to manage their infant's drug withdrawal traditionally leads to prolonged hospitalization for both mother and infant. This study examines the impact of a multidisciplinary follow-up clinic for infants discharged home on morphine.

METHODOLOGY

Records of full-term infants born to mothers with narcotic dependency were reviewed retrospectively. Two periods were compared: 1995-1997 (period A) and 1998 to September 1999 with clinic established (period B).

RESULTS

Twenty-five and 26 mothers were identified in periods A and B, respectively. Almost half had fewer than four antenatal clinic visits and most were on methadone with other substance usage. Despite higher maternal methadone doses (mean 48.5 vs 89.5 mg/day, P = 0.009) and withdrawal rates, the mean length of stay was significantly shorter for period B mothers (7.8 +/- 4.8 vs 5.4 +/- 3.3 days, P = 0.01) and babies (14.8 +/- 9.7 vs 8.7 +/- 7.2, P = 0.01). Median duration of morphine treatment was significantly shorter in period A (17 vs 60 days, P = 0.0001) when only four babies were discharged on morphine. In contrast, 18 treated period B babies were discharged on morphine. No families were lost to follow up. Compliance with clinic attendance was 92%.

CONCLUSIONS

Hospital stay was reduced with establishment of the clinic. The shorter treatment duration before establishment of the clinic could have been related to a lesser abstinence severity or a perceived need of a more rapid weaning prior to discharge. Further studies are needed to assess the impact of this model of care on the health outcome of the narcotic-dependent mother and infant unit.

A regional study of underlying congenital diseases in term neonates with necrotizing enterocolitis

AIM OF THE STUDY

The aetiology of necrotizing enterocolitis (NEC) remains poorly understood in infants of all gestation, particularly when it occurs at term. We hypothesize that NEC in term infants is rare but often associated with underlying congenital illnesses.

METHOD

Records of all term infants hospitalized with radiologically or surgically proven NEC in the 10 tertiary centres of two geographical regions of Australia during a 6.5-y period were reviewed. Regional birth data were obtained and a special care nursery survey was conducted.

RESULTS

Twenty-nine infants had proven NEC giving a population incidence of 0.05 per 1000 live births. Nineteen (66%) of them had underlying congenital diseases. Five (17%) infants had endocrine disorders, which included panhypopituitarism, hypothyroidism, hypoparathyroidism and congenital adrenal hyperplasia. Ten infants had congenital heart disease, eight being cyanotic. Six of them developed NEC prior to any invasive cardiac procedures. Seven of the other nine infants without any congenital diseases had perinatal risk factors associated with NEC. The severity of illness was not different amongst the three groups. All infants, except two, survived.

CONCLUSION

NEC in term infants is commonly secondary to or preceded by underlying congenital diseases. A considerable proportion of NEC cases had co-existing endocrine illnesses.

Attitudes of neonatal clinicians towards resuscitation of the extremely premature infant: an exploratory survey

OBJECTIVE

This study aims to explore the current attitudes of Australian neonatologists and nurses towards the resuscitation of extremely preterm infants.

METHODOLOGY

An anonymous questionnaire regarding resuscitation of infants of less than 28 weeks gestation was sent to all neonatologists and three registered nurses in each perinatal centre in Australia.

RESULTS

One hundred and thirty-three questionnaires were sent. A return rate of 93% and 73% was obtained from neonatologists and nurses, respectively. Twenty-two per cent of neonatologists would 'occasionally' resuscitate at 22 weeks while none of the nurses would. A considerable proportion of neonatologists (23%) but only a few nurses (6%) would 'quite often' resuscitate 23-week infants. The majority of neonatologists (85%) and nurses (88%) would 'almost always' resuscitate 24 week infants. More than half of the respondents would 'occasionally' resuscitate a 400-499 g infant and most would resuscitate infants weighing more than 500 g. Clinicians were not as optimistic of long-term outcome as they were for survival. Typically, only 52% of neonatologists and 38% of nurses thought babies of 25 weeks gestation had a greater than 50% chance of survival without major handicap. Parental wishes and the presence of congenital abnormalities were major influences on decision to resuscitate. Hypothetically, most respondents, more doctors than nurses, would consider initiating resuscitation without parental consent at a median gestation of 25 weeks.

CONCLUSIONS

The majority of Australian clinicians would resuscitate at a gestation of 24 weeks or greater or at a birth weight of over 500 g despite conservative estimates of intact survival. This survey has brought to light the importance of communication with parents prior to extreme premature birth.

An unusual presentation of sacral agenesis in a newborn baby

A potentially difficult situation can arise when a sick newborn baby presents with a common clinical sign that subsequently turns out to be a manifestation of a rare condition. The baby's birth sometimes results in the diagnosis of a new condition in other members of the family. Necrotising enterocolitis is the commonest surgical condition among babies in the neonatal intensive care unit (NICU). We report a case where abdominal distension in an acutely ill baby at high risk of necrotising enterocolitis masqueraded as an unusual presentation of familial sacral agenesis.

The French and North American phenotypes of pyruvate carboxylase deficiency, correlation with biotin containing protein by 3H-biotin incorporation, 35S-streptavidin labeling, and Northern blotting with a cloned cDNA probe

Cultured skin fibroblasts from 16 patients with either French or American pyruvate carboxylase (PC) deficiency were examined for their ability to incorporate 3H-biotin into proteins. Cell extracts were also examined for the presence of biotin-containing proteins with 35S-streptavidin, immunoreactive protein with anti-PC antibody, and PC mRNA by Northern blotting with a PC cDNA probe. All the North American presentation patients showed a 3H-biotin protein, a streptavidin protein, and an anti-PC precipitable protein at 125 kilodaltons on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cellular proteins. They also showed a detectable mRNA species for PC on Northern blotting. Of the French presentation patients, five showed very low or absent 3H-biotin protein, streptavidin protein, and anti-PC precipitable protein at 125 kilodaltons. Three French presentation patients showed PC protein to be present on the basis of these techniques. Similarly, five showed either very low or absent mRNA for PC on Northern blotting whereas three gave evidence of the presence of PC-specific mRNA. Thus, whereas the North American presentation of PC deficiency is associated with the presence of a mature biotin containing protein of the correct molecular weight, the French presentation may, in some (but not in all) cases, have both absent PC protein and absent PC mRNA.

Simultaneous preparation of the three biotin-containing mitochondrial carboxylases from rat liver

Affinity chromatography on avidin-Sepharose column was used to bind the biotin-containing carboxylases from rat liver. With a biotin gradient (0-0.3 mM), peaks of activity of pyruvate, propionly CoA and beta-methylcrotonyl CoA carboxylases co-eluted. Subsequent separation of the three carboxylases was attained using DEAE-Sepharose chromatography. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed each of the enzymes to be pure, with pyruvate carboxylase giving a single subunit band (Mr 130 000), propionyl-CoA carboxylase giving two bands (Mr 73 000 and 56 500) and beta-methylcrotonyl-CoA carboxylase giving two bands (Mr 75 000 and 60 000). The specific activity of propionyl-CoA carboxylase (15.8 munits/mg) and beta-methylcrotonyl-CoA carboxylase (24.2 munits/mg) were comparable with reported activities for these purified enzymes, while that of pyruvate carboxylase (1.25 munits/mg) was low. This is a suitable method for the simultaneous preparation of purified carboxylases for the specific purpose of raising antisera to these enzymes.

Prenatal diagnosis of pyruvate carboxylase deficiency

Prenatal diagnosis of pyruvate carboxylase (PC) deficiency was performed in a family at risk for the acute neonatal form of this disease which manifests secondary citrullinemia. The diagnosis of an affected child was confirmed by enzyme assay and 3H-biotin labelling of proteins in cultured fetal skin fibroblasts. Sufficient amniocytes were cultured in 3-4 weeks for enzyme analysis in two centres. Citrulline concentration in amniotic fluid (AF) was normal in the affected fetus.

The molecular basis for the two different clinical presentations of classical pyruvate carboxylase deficiency

Eight cases of isolated human pyruvate carboxylase deficiency were examined from seven families. Although all patients presented with a chronic lacticacidemia, two particular patients presented with the added features of hyperammonemia, citrullinemia, and hyperlysinemia. When cultured skin fibroblasts from these patients were examined for their ability to synthesize [3H]biotin-containing proteins, it was found that the two patients who presented with hyperammonemia, citrullinemia, and hyperlysinemia did not synthesise a protein of the correct subunit molecular weight (Mr = 125 K daltons) corresponding to pyruvate carboxylase. In addition, when skin fibroblast proteins were labeled with [35S]methionine, cross-reacting material (CRM) corresponding to pyruvate carboxylase was immunoprecipitated by antipyruvate carboxylase antiserum in most patients, but again the two patients with the atypical presentation showed no CRM. We propose that the different clinical presentation of human pyruvate carboxylase deficiency is a manifestation of two different mutations in the pyruvate carboxylase gene, one that results in the synthesis of a relatively inactive pyruvate carboxylase protein CRM(+ve) and one that results in the lack of expression of the gene in the form of a recognizable protein CRM(-ve).

[3H]biotin-labeled proteins in cultured human skin fibroblasts from patients with pyruvate carboxylase deficiency

Biotin containing carboxylases in cultured human skin fibroblasts were radioactively labeled by addition of [8,9-3H]biotin to biotin-depleted cell cultures. Three major bands were visualized by fluorography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the fibroblast proteins. These bands corresponded to pyruvate carboxylase (Mr = 125,000), the biotin-containing subunit of methyl crotonyl-CoA carboxylase (Mr = 75,000) and the biotin-containing subunit of propionyl-CoA carboxylase (Mr = 73,000) as judged by molecular weight markers, purified carboxylase protein standards, and interaction with monospecific antisera. Four out of 5 cell lines from patients with classical pyruvate carboxylase deficiency (less than 5% of normal activity) labeled with this technique displayed a normal band in the position of pyruvate carboxylase while one cell line showed complete absence of any labeled protein in this area. These results demonstrate heterogeneity in the etiology of pyruvate carboxylase deficiency.

Hydroxymethylglutaryl CoA lyase deficiency: features resembling Reye syndrome

A 2-year-old boy had acute fever, malaise, and somnolence with hepatomegaly, increased blood ammonia content (338 microM), high SGOT, low blood glucose content, and mild acidosis. A liver biopsy showed diffuse accumulation of lipid droplets in swollen hepatocytes, and abnormal urinary metabolites included beta-hydroxy-beta-methyl glutarate (HMG), beta-methylglutaconate, beta-hydroxyisovalerate, and beta-methylglutaric and glutaric acids. In cultured skin fibroblasts and liver, beta-hydroxy-beta-methyl glutaryl CoA lyase activity was about 10% of normal. Therefore, a genetic deficiency of HMGCoA lyase activity can cause a clinical syndrome similar to that of Reye syndrome when the patient is stressed by an acute viral infection.

Factors affecting glucose turnover and utilization in the neonatal subhuman primate (Macaca mulatta)

The rate of glucose turnover (RT) has been studied in 33 subhuman primate newborn (Macaca mulatta). There appears to be a linear relationship between RT and plasma glucose (G) such that RT = 1.053 G + 0.242. Liver enzymes show a change in specificity such that hexokinase is predominant in the preterm animals and glucokinase has little activity, while in the term animal these enzymes of of equal activity. In the 1-year-old animal glucokinase predominates. Hexokinase activity in the brain remains constant throughout development. These results imply that low blood glucose in the neonate is not associated with increased glucose utilization.

Factors affecting gluconeogenesis in the neonatal subhuman primate (Macaca mulatta)

The capacity for gluconeogenesis has been studied in 33 subhuman primate newborn (Macaca mulatta) in the basal steady state. Basal blood glucose levels were seen to rise with increasing postnatal age. Availability of the major gluconeogenic substrates, alanine and lactate, was adequate at times when blood glucose and the rate of gluconeogenesis were low. Hepatic and renal cortical content of the four key gluconeogenic enzymes was low during the 1st week of life compared to adult levels. Diminished induction of the gluconeogenic enzymes did not appear to be the cause of low blood glucose levels. The serum-free fatty levels were directly correlated to both the basal glucose levels and to the rate of gluconeogenesis.

Regulation of citrate transport and pyruvate dehydrogenase in rat kidney cortex mitochondria by bicarbonate

1. Bicarbonate increased citrate and 2-oxoglutarate accumulation when rat kidney cortex mitochondria were incubated with pyruvate or L(-)-palmitoyl carnitine in the presence of L-malate. 2. Bicarbonate stimulated the exit of citrate from mitochondria. The Km for bicarbonate was 13.5 mM and the Vmax was 0.59 nmol/min/mg of protein at 10 degrees. 3. The bicarbonate-stimulated exit of citrate from the mitochondria was prevented by inhibitors of the tricarboxylate, dicarboxylate, and phosphate transport systems. 4. The activity of pyruvate dehydrogenase was significantly increased by preincubation of rat kidney mitochondria with bicarbonate. This bicarbonate-induced activation was not observed in presence of inhibitors of citrate transport. Bicarbonate did not activate pyruvate dehydrogenase in rat heart mitochondria. Bicarbonate had no effect on pyruvate dehydrogenase activity in either broken mitochondria or whole tissue preparations. 5. The mechanism of this activation is discussed in the light of the known regulatory properties of pyruvate dehydrogenase, pyruvate carboxylase, and citrate synthase.

The development of pyruvate dehydrogenase in the subhuman primate Macaca mulatta

The development of total pyruvate dehydrogenase activity in the subhuman primate, Macaca mulatta, was investigated in brain, liver, kidney cortex, and skeletal and cardiac muscle. Newborn primates delivered prematurely at 135 days of gestation had only 32% of this enzyme activity present in the brain compared to the full-term animal. Full-term animals were similar to adults. All tissues showed high activities of enzyme at 1 year of age compared either with neonates or adults. Kidney cortex showed an increase in activity from 807 +/- 74 mumol/g/min in prematurely delivered neonates to a maximum of 3,769 +/- 275 mumol/g/min in 1-year-old animals. The results are discussed in relation to the developing energy requirements of the tissues concerned.

The effect of premature delivery on the development of gluconeogenic enzymes in the guinea pig

The activities of key gluconeogenic enzymes in the livers of newborn guinea pigs were monitored as a function of time following birth either vaginally at term or prematurely by cesarian section at 62 days of gestation. The activity of hepatic glucose-6-phosphatase rose dramatically from 1.40 +/- 0.26 mumol/min/g at birth to a maximum of 6.8 +/- 0.9 mumol/min/g at 24 hr in prematurely delivered animals although there was little significant change in activity in full term animals. The activity of hepatic fructose-1,6-diphosphatase and mitochondrial phosphoenolpyruvate carboxykinase changed little over the first 3 days of life in either full term or premature animals. Cytosolic phosphoenolpyruvate carboxykinase, on the other hand, had low activity at birth being 0.11 +/- 0.03 mumol/min/g in full term and 0.06 +/- 0.04 mumol in premature animals rising to values of 0.71 +/- 0.06 and 1.12 +/- 0.12 mumol/min/g, respectively, at 24 hr of life. Pyruvate carboxylase activities in the premature animals remained significantly lower than those in full term animals in the first 72 hr of life. Transient hypoglycemia was evident in the prematurely delivered animals, but not in the full term animals, the blood glucose values being 82 +/- 7 mg/100 ml for the full term animals and 20 +/- 8 mg/100 ml for the premature infants at 2 hr of life.

Citrate transport in guinea pig heart mitochondria

Guinea pig heart mitochondria loaded with [-14C]citrate show exchanges of radioactivity at 30 degrees C with added citrate, L-malate and phosphoenolpyruvate. These exchanges are inhibited by benzene-1,2,3-tricarboxylate. Measurements of rates of citrate transport indicate that the activity of this transporting system is low in heart mitochondria compared to that observed in liver mitochondria. The K(m) values obtained indicate a similarity to those obtained in liver. Citrate oxidation by coupled mitochondria was also found to be slow at 30 degrees C but was inhibited by benzene-1,2,3-tricarboxylate. The role of mitochondrial citrate transport in control of glycolytic flux in the heart is discussed.