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J C Partridge

Publications and source records attributed to J C Partridge.

At least 55 records · Page 3Linked to original sources
PubMed1992

Microspectrophotometric determinations of rod visual pigments in some adult and larval Australian amphibians.

Visual pigments from the red rods of adults of eight species of Australian anuran amphibians, from a variety of habitats, were analyzed by microspectrophotometry. The lambda max in all cases fell between 502 nm and 506 nm, and the absorption spectra were well fitted by an A1-based visual pigment template curve. Red rod pigments were also analyzed for a number of tadpoles. In some cases the data were best fitted with an A1-based visual pigment template, in other cases with an A2-based template, and finally some tadpoles appeared to have mixtures of the two pigments.

Animals↗
PubMed1992

Postischemic hyperglycemia is not protective to the neonatal rat brain.

Brain glucose concentration during and after hypoxia-ischemia may be one of the variables affecting outcome of asphyxial insults. Glucose given before global ischemic forebrain injury to adult rats increases morphologic brain damage, and postischemic insulin administration reduces selective neuronal necrosis and cortical infarction. Because glucose infusions are routinely used in the clinical management of perinatal asphyxia, we evaluated the role of glucose administration after ischemic neuronal damage to neonatal rat brain. Sprague-Dawley rat pups (postnatal d 7) were subjected to left common carotid artery ligation followed by 2.5 h of 8% oxygen (Levine procedure). The experimental group was subdivided so that pups received either systemic injections of glucose or saline immediately after the hypoxic insult. Animals were killed on postnatal d 12 and brain areas of ipsi- and contralateral cortex and caudate were calculated from camera lucida tracings. There was no significant difference in size of brain infarction between postischemic glucose-treated and post-ischemic saline-treated pups. However, hypoxic-ischemic brains did show more severe neuronal damage when hyperglycemia was induced after asphyxia. Because post-ischemic hyperglycemia does not attenuate and may exacerbate injury, we recommend careful monitoring of blood glucose so that hyperglycemia does not occur during resuscitation of asphyxiated infants.

Animals↗
PubMed1992

Postnatal human immunodeficiency virus antibody testing. The effects of current policy on infant care and maternal informed consent.

Routine human immunodeficiency virus (HIV) antibody screening of umbilical cord blood identifies neonates at risk for HIV infection but may hold risks as well as benefits for infants and mothers. We describe the effect of testing on infant placement and care and report the women's understanding of pretest counseling and consent. In a case-control analysis of 327 tested infants, seropositive infants (13) had a higher rate of discharge to home (62%) than did controls (31%). More case infants (100%) received follow-up care and vaccinations than control infants (46%). Of 32 women interviewed after HIV antibody test informed consent, only 31% understood that a positive cord blood test result was inconclusive for the infant, and most (78%) did not identify any associated socioeconomic risks. Most (88%) stated an interest in learning their serostatus, but only 22% returned for test results. Despite the benefits of HIV antibody testing of at-risk infants, current testing and counseling procedures inadequately inform women, limiting the testing benefits to them.

AIDS Serodiagnosis↗
PubMed1991

A new template for rhodopsin (vitamin A1 based) visual pigments.

A new template curve for rhodopsin visual pigments is presented. The template was constructed from absorbance spectra of purified bovine rhodopsin with an abscissa transform of lambda max/lambda. Absorbance curves generated from the template are compared with absorbance spectra of visual pigments measured in situ in single cells by microspectrophotometry (msp). The template was found to agree well with msp data which included visual pigments with lambda max values ranging from 450 to 570 nm. A cubic polynomial is given by which the new template may be fitted to the long wavelength limb of visual pigment data. A Chebyshev polynomial is also given which models the new template with a high degree of accuracy. This polynomial provides a convenient method for the computer generation of visual pigment absorbance curves.

Animals↗
PubMed1991

The modelling of optimal visual pigments of dichromatic teleosts in green coastal waters.

We have constructed a computer model that attempts to predict which pairs of rhodopsins are most suitable for making various luminosity and chromaticity discriminations in green coastal water. The model, which is based on the statistics of photon capture by retinal photoreceptors, predicts the optimal visual pigment pairs for different visual tasks. The results obtained from the model compare well with the rhodopsins possessed by dichromatic fish living at moderate depth in green coastal water.

Animals↗
PubMed1991

Monoclonal antibodies define linear and conformational epitopes of HIV-1 pol gene products.

Purified recombinant reverse transcriptase (RT) from human immunodeficiency virus type 1 (HIV-1) was used to raise 21 monoclonal antibodies with anti-RT specificities. The antibodies were characterized using Western blotting against native virus and recognized either the p66 or p66, p51 components of RT. Further immunoblotting using either cyanogen bromide fragmented RT or truncated mutants of RT along with cross-competition studies enabled the location of various immunogenic regions of RT to be identified. Three antibodies recognized a linear epitope in the N-terminal region (amino acids 128-176). Also, a neutralizing RT antibody recognized a conformational epitope in this region. Three monoclonals had epitopes mapped to linear sequences in the RNase H region at the C-terminus of the RT. Another neutralizing antibody, also requiring folding of the RT protein had its epitope more centrally located (231-353). Of the remaining 13 monoclonals, 7 were roughly located in the C-terminal region and required folding of the protein for epitope recognition and only three of the remaining six could be mapped to conformational epitopes in N-terminal and central regions of the RT. None of the antibodies tested recognized HIV-2 RT products p68 and p55 in Western blot.

Animals↗
PubMed1991

Influence of maternal body habitus and glucose tolerance on birth weight.

Many physicians believe that macrosomia is a hallmark of a pregnancy complicated by glucose intolerance. Because the prevalence of obesity is increased among women with gestational diabetes, fetal overgrowth may be attributable at least in part to maternal obesity. We studied 2069 black, Latina, Chinese, and white mother-infant pairs to determine the interaction between maternal body habitus, maternal glucose homeostasis, and certain indices of fetal growth. Chinese women had a significantly higher serum glucose 1 hour after administration of 50 g glucose (136.6 +/- 32.7 mg/dL) than any of the other three ethnic groups. Black women had a significantly lower value for glucose (114.8 +/- 28.2 mg/dL) than either Chinese or Latina women (124.9 +/- 31.4 mg/dL). Results for Latina and white women (121.5 +/- 26.2 mg/dL) were not significantly different. Body mass index (BMI) was used to classify the subjects. The regression coefficient for the entire sample indicated a modest association of glucose with increased birth weight when maternal BMI was controlled. The BMI of the Chinese infants had a significant association with higher concentrations of glucose after administration of 50 g glucose. Maternal body habitus should be considered a major confounder in studies of the relationship of maternal glucose tolerance and infant birth weight.

Birth Weight↗
PubMed1989

Interspecific variation in the visual pigments of deep-sea fishes.

Visual pigments in the rods of 38 species of deep-sea fish were examined by microspectrophotometry. 33 species were found to have a single rhodopsin with a wavelength of maximum absorbance (lambda max) in the range 470-495 nm. Such visual pigments have absorbance maxima close to the wavelengths of maximum spectral transmission of oceanic water. 5 species, however, did not conform to this pattern and visual pigments were found with lambda max values ranging from 451 nm to 539 nm. In 4 of these species two visual pigments were found located in two types of rod. Some 2-pigment species which have unusual red sensitivity, also have red-emitting photophores. These species have both rhodopsin and porphyropsin pigments in their retinae, which was confirmed by HPLC, and the two pigments are apparently located in separate rods in the same retinal area. In deep-sea fishes the occurrence of 'unusual' visual pigments seems to be correlated with aspects of the species' depth ranges. In addition to ecological influences we present evidence, in the form of lambda max spectral clustering, that indicates the degree of molecular constraint imposed on the evolution of visual pigments in the deep-sea.

Animals↗
PubMed1989

Epitope location of 13 anti-gag HIV-1 monoclonal antibodies using oligopeptides and their cross reactivity with HIV-2.

A series of 15-mer oligopeptides which overlapped by five amino acids (AA) across the p24 of HIV-1SF2 and a similar series across the p18 of HIV-1SF2 were used to identify the locations of 13 anti-gag monoclonal antibodies (MAbs). Three anti-p24 MAbs recognized sequences within the first 50 AA of the amino-terminal. Another anti-p24 recognized a conformational epitope in the centre of the protein and this MAb cross-reacted with two HIV-2 isolates suggesting conservation of this epitope between HIV-1 and HIV-2. One anti-p24 MAb recognized a linear sequence in the carboxy-terminal 100 AA and one p24 antibody was assumed to recognize a truly conformational epitope as it did not react with any of the linear peptides. Four anti-p18 MAbs were located at the carboxy-terminus of p18 with another MAb mapping slightly inwards from the carboxy-terminus and one anti-p18 MAb failed to bind to the p18 peptides. The carboxy-terminal distribution of the p18 MAbs indicated a highly immunogenic nature for this region in mice. None of the anti-p18 MAbs showed cross-reactivity with HIV-2 isolates, confirming the greater sequence variability of p18 over p24.

Amino Acid Sequence↗
PubMed1989

Visual pigments and the acquisition of visual information.

All the information available to the brain for the interpretation of the visual scene comes from the number of photons absorbed by a very limited number of photoreceptor types which are characterized by their spectral sensitivity. In vertebrates there are considerable differences in the spectral absorption of the rods and cones making up the retinal mosaic of different animals and, in some cases, including fish and primates, there are considerable differences between the cone sets of individuals within a species. Broadly speaking, the spectral sensitivity of the photoreceptors is related to the spectral distribution of the ambient light and this is particularly true of the colour-biased light under water. When an animal migrates from one visual environment to another, its cone complement may change to that suited to the new conditions. However, significant differences between the cone sets of animals living within the same environment and colour vision polymorphism within a species suggest that visual tasks critical to survival or breeding success require particular visual pigment sets. A start has been made in trying to understand what tasks are best served by different pigment sets.

Animals↗
PubMed1987

Visual pigment polymorphism in the guppy Poecilia reticulata.

Visual pigment polymorphism similar to that found in primates is described in the photoreceptors of wild-caught guppies (Poecilia reticulata). Microspectrophotometric examination of retinal cells revealed rod visual pigments with a lambda max close to 503 nm. Classes of cones with lambda max around 410 and 465 nm were found, together with a population of pigments in the 529-579 nm range. It is in these long-wavelength cones that polymorphism occurs. Male guppies are highly polymorphic for body colour and it is possible that the cone polymorphism is related to the appreciation of the different yellow, orange and red carotenoid colour spots that are used in sexual display.

Animals↗
PubMed1987

Lymphocyte abnormalities in infants born to drug-abusing mothers.

To evaluate the possible effects of maternal intravenous drug use on infant immunity, we measured the in vitro peripheral blood mononuclear cell proliferative responses to phytohemagglutinin (PHA) and pokeweed mitogen, T cell subset numbers, immunoglobulin levels, and titers of antibodies to cytomegalovirus (CMV) and human immunodeficiency virus (HIV) in a group of drug-abusing mothers and their infants. Infants of drug abusers had a lower proliferative response to mitogen, associated with altered kinetics of the maximum response to PHA. The OKT4/OKT8 ratio decreased with age in the drug-exposed infants compared with control infants (P less than 0.005). There was no evidence of CMV infection in either group. One mother and her infant had antibody to HIV. Our data demonstrate that infants of intravenous drug-using mothers have distinct immunologic differences at birth compared with non-drug-exposed infants and that these persist throughout the first year of life. The cause appears unrelated to intrauterine viral infection, suggesting a direct toxic effect of the drugs on fetal immunologic development.

Antibodies, Viral↗
PubMed1983

Optimal timing for diagnostic cranial ultrasound in low-birth-weight infants: detection of intracranial hemorrhage and ventricular dilation.

Intracranial hemorrhage and posthemorrhagic ventricular dilation are common problems in small preterm infants. To determine the optimal timing for ultrasound diagnosis of these abnormalities, we studied 64 preterm infants (less than 1,500 gm) by sequential cranial ultrasonography from birth until one year of age or until death. The optimal timing for ultrasound diagnosis of intracranial hemorrhage is days 4 to 7 with follow-up at day 14. The most efficient time for ultrasound examination to diagnose ventricular dilation was day 14 with follow-up at 3 months. Intracranial hemorrhage was diagnosed by ultrasound in 35 of the 64 patients (55%). In 18 of the 64 infants (28%) significant ventricular dilation was diagnosed by ultrasound during the first three months.

Cerebral Hemorrhage↗
PubMedDate not supplied

Visual pigments, cone oil droplets and ocular media in four species of estrildid finch.

A microspectrophotometric study was conducted on the retinal photoreceptors of four species of bird: cut-throat finches (Amadina fasciata), gouldian finches (Erythrura gouldiae), white-headed munias (Lonchura maja) and plum-headed finches (Neochmia modesta). Spectral characteristics of the photoreceptors in all four species were very similar. Rods contained a medium-wavelength-sensitive visual pigment with a wavelength of maximum absorbance at 502-504 nm. Four spectrally distinct types of single cone contained a visual pigment with wavelength of maximum absorbance at either 370-373 nm (ultraviolet-sensitive), 440-447 nm (short-wavelength-sensitive); 500 nm (medium-wavelength-sensitive) or 562-565 nm (long-wavelength-sensitive). Oil droplets in the ultraviolet-sensitive single cones showed no detectable absorption between 330 nm and 800 nm. Oil droplets in the short-, medium-, and long-wavelength-sensitive single cones had cut-off wavelengths at 415-423 nm, 510-520 nm and 567-575 nm, respectively. Double cones contained the visual pigment with wavelength of maximum absorbance at 562-565 nm observed in long-wavelength-sensitive single cones. Only the principal member of the double cone pair contained an oil droplet (P-type, cut-off wavelength at 414-489 nm depending on species and retinal location). Spectral transmittance of the intact ocular media of each species was measured along the optic axis. Wavelengths of 0.5 transmittance for all species were very similar (316-318 nm).

Animals↗
PubMedDate not supplied

Delivery room resuscitation decisions for extremely low birthweight infants in California.

OBJECTIVE: To characterize physician-parent counseling and delivery room resuscitation of extremely low birthweight (ELBW) infants. STUDY DESIGN: Cross-sectional survey of 473 California neonatologists detailing counseling patterns, resuscitation thresholds, and acceptance of parental decision making. RESULTS: The response rate was 61%. After 23 weeks' gestation, > 80% of neonatologists counseled parents expecting ELBW infants. All (> 99%) counseled parents about mortality; > 25% reported not discussing limiting resuscitation or death despite resuscitation. Decisions to limit resuscitation were affected by congenital anomalies, parents' wishes, or perceptions of pain, suffering, and quality of life. Nearly 70% of neonatologists supported parental decision making at 22 to 23 weeks, whereas 66% to 74% responded that parents should not be allowed to make nonresuscitation decisions after 26 weeks. Median resuscitation thresholds were 23 weeks (range 20-28) and 500 g (range 350-1000). CONCLUSIONS: Neonatologists' failure to discuss nonresuscitation options, variations in resuscitation thresholds, and unwillingness to accept nonresuscitation decisions for more mature ELBW infants may restrict parental decision making.

Adult↗
PubMedDate not supplied

Cocaine, nicotine, caffeine, and metabolite plasma concentrations in neonates.

The objective of this study was to measure the umbilical cord plasma levels of cocaine, nicotine, caffeine, and their metabolites. Thirty-six neonates at risk for prenatal cocaine exposure were prospectively enrolled. Umbilical cord plasma was analyzed by gas chromatography-mass spectroscopy for cocaine, cocaethylene, benzoylecgonine (BZE), nicotine, cotinine, and caffeine. Eighteen neonates were plasma positive for BZE, and 50% of these were also positive for cocaine. Cocaethylene was not found. The maximum plasma cocaine concentration was 88 ng/mL (mean, 39 ng/mL). The maximum plasma BZE concentration was 3880 ng/mL (mean, 844 ng/mL). Among BZE-positive babies, the mean plasma drug levels were as follows: nicotine, 1.8 ng/mL; cotinine, 94 ng/mL; and caffeine, 1205 ng/mL. Among the BZE-negative babies, the mean plasma drug levels were as follows: nicotine, 5.2 ng/mL; cotinine, 97 ng/mL; and caffeine, 1440 ng/mL. These cocaine levels raise the possibility of pharmacological effects of cocaine in the early neonatal period.

Caffeine↗