Integrating neurocritical care approaches into neonatology: should all infants be treated equitably?

To improve the neurologic outcomes for infants with brain injury, neonatal providers are increasingly implementing neurocritical care approaches into clinical practice. Term infants with brain injury have been principal beneficiaries of neurologically-integrated care models to date, as evidenced by the widespread adoption of therapeutic hypothermia protocols for hypoxic-ischemic encephalopathy. Innovative therapeutic and diagnostic support for very low birth weight infants with brain injury has lagged behind. Given that concern for significant future neurodevelopmental impairment can lead to decisions to withdraw life supportive care at any gestational age, providing families with accurate prognostic information is essential for all infants. Current variable application of multidisciplinary neurocritical care approaches to infants at different gestational ages may be ethically problematic and reflect distinct perceptions of brain injury for infants born extremely premature.

Inhalation toxicology of decamethylcyclopentasiloxane (D5) following a 3-month nose-only exposure in Fischer 344 rats.

D5 is a low-molecular-weight cyclic siloxane used for industrial and consumer product applications. The objective of the present study was to evaluate the subchronic toxicity of D5 following a 3-month nose-only inhalation exposure. In addition, animals from both sexes of the control and high dose groups were allowed a 4-week recovery period to observe reversibility, persistence, or delayed occurrence of any potential adverse effects. Male and female Fischer 344 rats were exposed for 6 h/day, 5 days/week for 3 months to target concentrations of 0 (30/sex/group), 26 (20/sex/group), 46 (20/sex/group), 86 (20/sex/group), and 224 (30/sex/group) ppm D5. Recovery groups (0 and 224 ppm) comprised 10 rats/sex/group. Body weights and food consumption were monitored at least twice weekly over the course of exposures. Approximately 16 h preceding euthanasia, animals were transferred into metabolism caging for urine collection and were fasted. Rats were anesthetized with pentobarbital and euthanized by exsanguination. Blood was collected for hematological and clinical biochemical analyses. Selected organ weights were measured and a complete set of tissues was taken for histopathological examination. There were several minor changes observed in clinical biochemistry parameters; the most notable was an increase in gamma glutamyl transferase (gamma-GT) in both sexes at the high dose. In females, this effect was dose-related (46-224 ppm) and did not recover upon cessation of exposure. Additionally, there was an decrease in serum lactate dehydrogenase (LDH) observed in females at 86 and 224 ppm which was not resolved during recovery. There was an increase in absolute and/or relative liver weight in rats of both sexes. Taken together, these data suggest that the female rat is more sensitive to the actions of D5 on the liver. Exposure-related increases in absolute and relative lung weights were observed in both sexes at terminal necropsy. This observation was not noted in males in the recovery phase, but was still present in females. Finally, histopathological evidence indicated the primary target organ following D5 inhalation exposure is the lung, with an increase in focal macrophage accumulation and interstitial inflammation in the lungs of male and female rats exposed to 224 ppm D5. This observation did not appear to resolve at the end of a 1-month period of nonexposure. The incidence of these changes was also slightly increased in rats of both sexes exposed to 86 ppm D5. These data suggest that nose-only D5 vapor inhalation provokes minimal changes in the lung which are similar in incidence and severity to spontaneously occurring changes in control animals after nose-only exposures. There were no histopathological findings noted in the livers which support this organ as a target in this study, despite the observed changes in organ weight and in some serum chemistry parameters.

Toxicology and humoral immunity assessment of decamethylcyclopentasiloxane (D5) following a 1-month whole body inhalation exposure in Fischer 344 rats.

D5 is a low-molecular-weight cyclic siloxane used for industrial and consumer product applications. The objective of the present study was to assess potential toxic and immunomodulatory consequences of inhalation exposure to D5. Male and female Fischer 344 rats (25/group) were exposed by whole body inhalation to 0, 10, 25, 75, or 160 ppm D5 6 h/day, 7 days/week for 28 days. Clinical signs, body weights, and food consumption were recorded. On the day following the final exposure, 10 rats/group/sex were euthanized and a complete necropsy performed. Following a 14-day nonexposure recovery period, the remaining 5 rats/sex/group were necropsied. Body and organ weights were obtained and a complete set of tissues was taken for histopathology. Samples were also collected for serum chemistry, hematology, and urinalysis. Immunotoxicology-designated rats (10/sex/group) were immunized with sheep erythrocytes (sRBC) 4 days prior to euthanasia and cyclophosphamide (CYP) was administered i.p. to positive controls on days 24 through 28. The anti-sRBC antibody-forming cell (AFC) response was evaluated in a standard plaque assay. Blood was also collected for examination in the anti-sRBC enzyme-linked immunosorbant assay (ELISA). D5 exposure did not modulate humoral immunity, while the internal control, CYP, produced the expected suppression of the AFC response. D5 exposure caused no adverse effects on body weight, food consumption, or urinalysis parameters. Serum alkaline phosphatase (SAP) was significantly decreased in females at terminal (12%, 160 ppm) and recovery sacrifice. A significant increase in the liver-to-body weight ratio was observed in female animals at the end of exposures (13%, 160 ppm), but was not noted in recovery animals from the same exposure group. In males, significant increases in liver-to-body weight (5%) and thymus-to-body weight (14%) ratios were also noted at the high dose at terminal sacrifice and were not present at recovery. At recovery only, a significant increase in spleen-to-body weight ratios (14 and 17%; 25 and 160 ppm, respectively) was noted. At the end of exposure, histopathological analysis indicated an increased incidence and severity of nasal (Level 1) goblet cell proliferation. Focal macrophage accumulation in the lung was also observed to be increased in incidence in both sexes at 160 ppm. At the end of the recovery period, the effects in both of these organs appeared to be reversible. In summary, D5 inhalation exposure did not alter humoral immunity and caused only minor, transient changes in hematological, serum chemistry, and organ weight values. Histopathological changes were confined to the respiratory tract and appeared to be reversible. The no observed effect level for systemic toxicity, based primarily on the liver weight changes, was 75 ppm.

Cellular and molecular mechanisms of action of linuron: an antiandrogenic herbicide that produces reproductive malformations in male rats.

Antiandrogenic chemicals alter sex differentiation by several different mechanisms. Some, like flutamide, procymidone, or vinclozolin compete with androgens for the androgen receptor (AR), inhibit AR-DNA binding, and alter androgen-dependent gene expression in vivo and in vitro. Finasteride and some phthalate esters demasculinize male rats by inhibiting fetal androgen synthesis. Linuron, which is a weak competitive inhibitor of AR binding (reported Ki of 100 microM), alters sexual differentiation in an antiandrogenic manner. However, the pattern of malformations more closely resembles that produced by the phthalate esters than by vinclozolin treatment. The present study was designed to determine if linuron acted as an AR antagonist in vitro and in vivo. In vitro, we (1) confirmed the affinity of linuron for the rat AR, and found (2) that linuron binds human AR (hAR), and (3) acts as an hAR antagonist. Linuron competed with an androgen for rat prostatic AR (EC(50) = 100-300 microM) and human AR (hAR) in a COS cell-binding assay (EC(50) = 20 microM). Linuron inhibited dihydrotestosterone (DHT)-hAR induced gene expression in CV-1 and MDA-MB-453-KB2 cells (EC(50) = 10 microM) at concentrations that were not cytotoxic. In short-term in vivo studies, linuron treatment reduced testosterone- and DHT-dependent tissue weights in the Hershberger assay (oral 100 mg/kg/d for 7 days, using castrate-immature-testosterone propionate-treated male rats; an assay used for decades to screen for AR agonists and antagonists) and altered the expression of androgen-regulated ventral prostate genes (oral 100 mg/kg/d for 4 days). Histological effects of in utero exposure to linuron (100 mg/kg/d, day 14-18) or DBP (500 mg/kg/d, day 14 to postnatal day 3) on the testes and epididymides also are shown here. Taken together, these results support the hypothesis that linuron is an AR antagonist both in vivo and in vitro, but it remains to be determined if linuron alters sexual differentiation by additional mechanisms of action.

A computerized system for retrieval of case information in a veterinary diagnostic laboratory.

Morbidity and mortality data are necessary bases for the decision-making processes relevant to allocation of public funds for animal disease diagnoses and research. A system for information storage and retrieval capable of handling diagnostic data such as results of microbiology, parasitology, necropsy, and histopathology as well as demographic data such as owner, species, sex, breed, or geographic origin of the animal is described. This information is available to veterinarians, epidemiologists, herdsmen, and others involved in disease prevention or control efforts. The system described utilizes natural language, thus overcoming difficulties encountered in systems with numerical intermediates. Used and revised for the last 10 years, the system described has proved useful for annual administrative quantitation of services performed. In fact, the Concordance Index serves as the annual report of the University of Missouri Veterinary Medical Diagnostic Laboratory. Having accurate detailed information on individual cases, as well as a variety of composite data, has been extremely helpful in the documentation necessary for attracting funding for study of specific disease states.

Mycobacterial osteomyelitis in captive marsupials.

Mycobacterial osteomyelitis was detected in 3 marsupials exhibited at the National Zoological Park, Washington, DC. One Matschiei's tree kangaroo (Dendrolagus matschiei), 1 Parma wallaby (Macropus parma), and 1 long-nosed rat kangaroo (Potorous tridactylus) were affected. The Parma wallaby had disseminated granulomatosis. Acid-fast organisms were observed in the bone marrow of the wallaby, using the auramine-O-rhodamine fluorescent technique; however, cultures were negative. The tibiotarsal joint of the rat kangaroo contained exudate, with fistulous tracts and necrosis of the articular surface. Granulomas with necrotic centers from this area were positive by auramine-O-rhodamine but were negative on culture. The tree kangaroo had thickening of the right ischium, with a pocket of exudate caudal to the acetabulum. The musculature in the acetabular area was thickened and fibrotic. Mycobacterium avium serotype 15 was isolated from the ischium and liver of this animal.

Echocardiographic detection of tricuspid atresia in two foals.

M-mode, 2-dimensional, and contrast echocardiographic studies were used to detect tricuspid atresia in 2 foals. M-mode echocardiographic findings included a small right ventricle, large left ventricle, large mitral valve excursion, large left atrium (foal 2), dropout of the cranial aspect of the aortic root, and a thick band of echoes in the tricuspid valve region. These findings were confirmed by 2-dimensional echocardiography. In addition, a large right atrium, persistent foramen ovale, ventricular septal defect, and large mitral valve apparatus were imaged. One foal also had a thick right atrial wall. Contrast echocardiography confirmed the intracardiac flow of blood from right to left atrium and then to the left ventricle, followed by simultaneous opacification of the right ventricle and aorta. The use of these echocardiographic techniques enables accurate antemortem diagnosis and prognosis of tricuspid atresia in the foal.

Disseminated sporotrichosis in a cat.

Sporothrix (Sporotrichum) schenckii was identified as the causative agent of a large pyogranulomatous lesion on the right forepaw of a cat. Organisms also were observed in axillary lymph nodes of the affected forelimb and in the lungs and liver of the cat. The agent was transmitted to another domestic cat and to mice.

Canine parvovirus infection in South American canids.

Canine parvovirus (CPV) infections occurred in 5 of 35 South American canids at the Department of Conservation (DC), a breeding facility of the National Zoological Park in Front Royal, Va. The clinical signs were anorexia, lethargy, diarrhea, and vomiting. Three of the affected canids survived and had high hemagglutination-inhibition titers to CPV in the recovery period. Necropsy of the 2 that died revealed extensive necrosis of the intestinal mucosa; CPV particles were observed by electron microscopy in the intestinal contents of both animals. Six of the 30 canids that remained healthy had high hemagglutination-inhibition titers to CPV prior to the episode of illness, indicating earlier subclinical exposure. Pet dogs belonging to DC personnel that were screened as a possible source of the infection had no evidence of disease. All canids (including pet dogs) on the DC grounds were vaccinated repeatedly with a killed feline panleukopenia virus product after the episode, with little or no effect on existing titers.

Hemolytic uremic-like syndrome in two horses.

A syndrome characterized clinically by oliguria, progressive severe azotemia, and edema of the abdomen and groin was seen in 2 horses. Treatment with fluids, diuretics, and corticosteroids administered intravenously was ineffective, and the horses were euthanatized. Microscopically, there was severe necrotizing angiopathy with profuse fibrin deposition in renal glomeruli and sinusoids of peripheral lymph nodes. The signs observed in the horses resembled hemolytic-uremic syndrome in human beings.

Clinicopathologic correlations of tuberculosis in large zoo mammals.

In August 1978, a black rhinoceros at the National Zoological Park died with generalized tuberculosis caused by Mycobacterium bovis. A 2nd black rhinoceros was euthanatized 9 months after M bovis was cultured from its lungs. After these 2 deaths, numerous large zoo mammals that had been potentially exposed were subjected to various procedures to ascertain their status regarding tuberculosis. The procedures were: intradermal tuberculin testing, evaluation of delayed hypersensitivity reaction on biopsy specimens, enzyme-linked immunosorbent assay (ELISA) testing, and culture of various secretions and organs. Several of the animals in this series died during the study. These were necropsied and examined for evidence of mycobacterial infection. The results of tuberculin testing varied from species to species and from site to site within a species. Delayed hypersensitivity responses generally correlated well with the amount of swelling at the tuberculin site. In some cases, however, positive reactions were found without any delayed hypersensitivity response. Results of ELISA testing were confirmatory in tuberculous animals. Several species were judged to be nonspecific reactors, based on positive or suspect tuberculin test results, with negative ELISA results and necropsy findings.

Novel NKX2.1 mutation associated with hypothyroidism and lethal respiratory failure in a full-term neonate.

We report a case of lethal neonatal hypoxic respiratory failure and hypothyroidism in an infant with a novel missense mutation in NKX2.1.

Polymorphisms in the fetal progesterone receptor and a calcium-activated potassium channel isoform are associated with preterm birth in an Argentinian population.

OBJECTIVE: To investigate genetic etiologies of preterm birth (PTB) in Argentina through evaluation of single-nucleotide polymorphisms (SNPs) in candidate genes and population genetic admixture. STUDY DESIGN: Genotyping was performed in 389 families. Maternal, paternal and fetal effects were studied separately. Mitochondrial DNA (mtDNA) was sequenced in 50 males and 50 females. Y-chromosome anthropological markers were evaluated in 50 males. RESULT: Fetal association with PTB was found in the progesterone receptor (PGR, rs1942836; P=0.004). Maternal association with PTB was found in small conductance calcium activated potassium channel isoform 3 (KCNN3, rs883319; P=0.01). Gestational age associated with PTB in PGR rs1942836 at 32-36 weeks (P=0.0004). MtDNA sequencing determined 88 individuals had Amerindian consistent haplogroups. Two individuals had Amerindian Y-chromosome consistent haplotypes. CONCLUSION: This study replicates single locus fetal associations with PTB in PGR, maternal association in KCNN3, and demonstrates possible effects for divergent racial admixture on PTB.

Oral toxicity study of 2-pentenenitrile in rats with reproductive toxicity screening test.

A combined repeated-dose toxicity study with reproduction was conducted with 2-pentenenitrile (2-PN). Rats (10/sex per dose level) were dosed with 2-PN once daily by gavage at dose levels of either 0, 1, 3, or 10 mg kg(-1) day(-1) for 28 days, prior to and during cohabitation, and through day 3 of lactation. General clinical observations were recorded daily; body weights were recorded weekly. A neurobehavioral evaluation consisting of a functional observational battery and motor activity was conducted in all parental rats (10/sex per group). Clinical pathology parameters (hematology, clinical chemistry, coagulation) were measured in parental rats. Pup weights and clinical signs were recorded at birth and on lactation day 4. Parental rats were given a gross pathological examination, organ weights were obtained, and histological examination was conducted for the control and 10 mg kg(-1) day(-1) groups. No effects were seen with regard to mortality, clinical signs, functional observational battery and motor activity, hematology, or organ weights. Females receiving 10 mg/kg and males from all dose groups showed lower body weight gains and feed efficiency. Increased albumin concentrations were seen in both sexes given 10 mg/kg. Females in the 10 mg/kg group showed degeneration of the olfactory mucosa. No effects on the numbers of pups born, number surviving to lactation day 4, pup weight, and no gross anatomical development changes were observed. Under the conditions of this study, the no-observed-effect level (NOEL) for systemic toxicity in rats was 3 mg kg(-1) day(-1), based on degeneration of olfactory mucosa in females at 10 mg kg(-1) day(-1). The NOEL for reproductive and neurobehavioral toxicity in rats and for toxicity to offspring was 10 mg kg(-1) day(-1), the highest dose level tested.

Selected lesions of dioxin in laboratory rodents.

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) has been the subject of intensive investigations in laboratory animals during the last 2 decades. Toxicity studies have been conducted in several species of rodents and include several carcinogenicity studies as well as numerous mechanistic studies initiated to elucidate dioxin's mode of action, as both a carcinogen and a toxicant. Hepatotoxicity is a primary effect of dioxin. There has been an increase in hepatocellular tumors reported in both rats and mice exposed to dioxin. In addition to neoplastic changes, dioxin causes a spectrum of toxic changes in the liver. Additional neoplastic changes include subcutaneous fibrosarcomas and thyroid follicular cell tumors in both rats and mice and histiocytic sarcomas in mice. Dioxin causes developmental effects in the palate and kidney of mice. Changes in the female reproductive tract include ovarian atrophy, sertoliform hyperplasia, and Sertoli cell tumors. Dosing in utero results in gross malformations of the external genetalia. The effects of dioxin on the rodent model of endometriosis are described. In males, there are lowered sperm counts in the epididymis and minor testicular effects following gestational administration of dioxin. Both estrogenic and antiestrogenic-like effects have been ascribed to dioxin in laboratory animals; these activities are the result of dioxin-specific pathways resulting in the same end points as classic reproductive toxicants.

Dihydrostreptomycin toxicity in the Mongolian gerbil, Meriones unguiculatus.

A fatal syndrome of acute toxicity was produced in Mongolian gerbils following the injection of a penicillin-dihydrostreptomycin-procaine combination. The toxicity was determined to be due to the dihydrostreptomycin component. Fifty milligrams of dihydrostreptomycin produced 80-100% mortality in 55-65 g gerbils.

Spontaneous lesions in aging FVB/N mice.

The FVB/N mouse strain was created in the early 1970s and has since been used extensively in transgenic research because of its well-defined inbred background, superior reproductive performance, and prominent pronuclei of fertilized zygotes, which facilitate microinjection of DNA. Little is known, however, about the survivability and spontaneous disease of nontransgenic FVB/N mice. Therefore, the purpose of this study was to determine survival to 24 mo of age and the incidence of neoplastic and nonneoplastic disease at 14 and 24 mo of age. At 14 mo of age, the incidence of tumor-bearing mice was 13% in males (n = 45) and 26% in females (n = 98). All tumors in males and most in females at this time were alveolar-bronchiolar (AB) neoplasms of the lung. Survival to 24 mo of age was approximately 60% in both sexes (29/50 males, 71/116 females), and the incidence of mice with tumors at this time was 55% in males and 66% in females. In decreasing order of frequency, the following neoplasms were observed in > 5% of subjects: in males, lung AB tumors, liver hepatocellular tumors, subcutis neural crest tumors, and Harderian gland adenomas; in females, lung AB tumors, pituitary gland adenomas, ovarian tumors (combined types), lymphomas, histiocytic sarcomas, Harderian gland adenomas, and pheochromocytomas. Compared with other mouse strains, the observed incidences of tumors in FVB/N mice suggest a higher than usual rate of lung tumors and a lower than usual incidence of liver tumors and lymphomas. This tumor profile should be considered in the interpretation of neoplastic phenotypes in FVB/N-derived transgenic lines.

Toxic hepatopathy in neonatal foals.

Six foals of three different breeds, born to healthy mares, appeared normal at birth, and died at two to five days of age with icterus, ataxia, head pressing, and terminal hepatic coma. Their livers were less than one-half normal weight. Most of the liver was dark red-brown and slightly rubbery. Histologically, these areas were characterized by severe bile ductule proliferation, mild portal tract fibrosis, and massive hepatocellular necrosis and lobular collapse. A small proportion of the liver, usually on the peripheral part of the lobes, was grossly light brown and slightly raised. Histologically, these areas had mild to severe bile stasis in canaliculi. In the thin marginal zone between the severely affected and mildly affected liver, there was mild bile ductule proliferation and periportal fatty change and necrosis. Alzheimer's type II cells, characteristic of hepatoencephalopathy, were numerous in the brains of all foals. Within two hours after birth, all the foals had been given an oral proprietary nutritional paste, the ingredients of which included a viable Aspergillus sp and an iron compound. Similar lesions were produced in an experimental foal.

Spontaneous and chemically induced proliferative lesions in Tg.AC transgenic and p53-heterozygous mice.

Recently, the use of selected genetically altered mouse models in the detection of carcinogens after short-term chemical exposures has been evaluated. Studies of several chemicals conducted by the National Toxicology Program in Tg.AC transgenic and heterozygous p53-deficient mice have been completed recently and represent a major contribution to this effort, as well as the largest accumulation to date of toxicologic pathology data in these 2 lines of mice. The purpose of this report is to describe the proliferative target organ effects observed in this set of studies, as well as to present the tumor profile in the control groups of this data set. These findings provide a comprehensive toxicologic assessment of these 2 genetically altered mouse strains, which are of emerging importance in toxicologic pathology.

Hepatocarcinogenicity of chlordane in B6C3F1 and B6D2F1 male mice: evidence for regression in B6C3F1 mice and carcinogenesis independent of ras proto-oncogene activation.

Logistic regression analysis of age-specific prevalences for neoplastic and non-neoplastic liver lesions was used to examine treatment responses for B6C3F1 and B6D2F1 male mice continuously exposed to chlordane (55 p.p.m.) and to determine whether neoplasms were dependent on continuous exposure in the B6C3F1 mice. In order to determine if ras oncogene activation plays a role in the carcinogenicity of chlordane and whether the activation is dependent on genetic background, liver tumors from chlordane-treated B6C3F1 and B6D2F1 mice were analyzed for the presence of activating mutations in the ras oncogene. The overall liver tumor prevalence at terminal killing was nearly 100% for both strains; however, the age-specific prevalence increased more rapidly in B6C3F1 mice than in B6D2F1 mice. Tumor-bearing B6C3F1 mice had an average of two or more tumors per liver than B6D2F1 mice at their respective terminal killings (5.4 versus 3.3). When chlordane exposure was discontinued for a group of B6C3F1 mice ('stop' group) at 491 days of age, overall tumor multiplicity significantly decreased by 30% from an average of 4.4 per tumor-bearing-animal at 525 days to 3.1 at terminal killing (568 days). Over the same time period the prevalence of hepatocellular carcinomas significantly decreased from 80 to 54% and adenomas from 100 to 93% by terminal killing in B6C3F1 'stop-group' mice. Chlordane induced diffuse hepatocellular centrilobular hypertrophy, frequent multinucleate hepatocytes, toxic change and hepatoproliferative lesions composed predominantly of acidophilic hepatocytes in nearly 100% of both the B6C3F1 and B6D2F1 mice. The development of histological evidence of toxicity closely paralleled the temporal development of hepatocellular neoplasia and decreased in severity when the tumor burden was maximal. No H- or K-ras mutations were detected in the chlordane-induced hepatocellular tumors in B6C3F1 mice (15 adenomas and 15 carcinomas) or B6D2F1 mice (10 adenomas and 10 carcinomas). In conclusion, chlordane induced liver tumors in both B6C3F1 and B6D2F1 male mice by mechanisms independent of ras oncogene activation and 30% of both benign and malignant liver tumors in the B6C3F1 mice regressed after exposure was discontinued.