Biomedical subjects

S Shukla

Publications and source records attributed to S Shukla.

At least 19 recordsLinked to original sources

PubMed2006

Isolated inflammatory sphenoiditis with multiple unilateral cranial nerve palsies.

Isolated sphenoidits is a rare entity that often presents with vague, non-specific symptoms. We present the case of a 36-year-old Middle Eastern man, who developed headache and a painful right eye. A diagnosis of acute sphenoiditis was made. Shortly afterwards, he developed diplopia due to isolated abducent nerve involvement. Within two months, the extent of cranial nerve involvement had increased to include cranial nerves II, III, and V. Subsequently, this was treated by functional endoscopic sinus surgical drainage and biopsy. Histology revealed inflammatory changes. The patient made a dramatic recovery post-operatively, with resolution in all symptoms.

Adult↗

PubMed2006

Thermal evaporation processing of nano and submicron tin oxide rods.

Nano and submicron rods of semiconductor tin oxide (SnO2) have been synthesized via thermal evaporation technique. Various substrates such as oxidized silicon (Si/SiO2), porous alumina (Al2O3), oxidized and anodized titanium (Ti/TiO2), with the sputtered platinum (Pt) catalyst, have been utilized for this purpose. The effect of Pt sputtering time and the nature of the substrate on the size distribution and the morphology of the SnO2 rods and their substrate-surface-coverage have been investigated. The formation of nano and submicron SnO2 rods has been attributed to the vapor-liquid-solid (VLS) and vapor-solid (VS) growth mechanisms depending on the processing conditions.

Journal Article↗

PubMed2006

Neuroprotective and neurorescue effect of black tea extract in 6-hydroxydopamine-lesioned rat model of Parkinson's disease.

In the present study, an attempt has been made to explore the neuroprotective and neuroreparative (neurorescue) effect of black tea extract (BTE) in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD). In the neuroprotective (BTE + 6-OHDA) and neurorescue (6-OHDA + BTE) experiments, the rats were given 1.5% BTE orally prior to and after intrastriatal 6-OHDA lesion respectively. A significant recovery in d-amphetamine induced circling behavior (stereotypy), spontaneous locomotor activity, dopamine (DA)-D2 receptor binding, striatal DA and 3-4 dihydroxy phenyl acetic acid (DOPAC) level, nigral glutathione level, lipid peroxidation, striatal superoxide dismutase and catalase activity, antiapoptotic and proapoptotic protein level was evident in BTE + 6-OHDA and 6-OHDA + BTE groups, as compared to lesioned animals. BTE treatment, either before or after 6-OHDA administration protected the dopaminergic neurons, as evident by significantly higher number of surviving tyrosine hydroxylase immunoreactive (TH-ir) neurons, increased TH protein level and TH mRNA expression in substantia nigra. However, the degree of improvement in motor and neurochemical deficits was more prominent in rats receiving BTE before 6-OHDA. Results suggest that BTE exerts both neuroprotective and neurorescue effects against 6-OHDA-induced degeneration of the nigrostriatal dopaminergic system, suggesting that possibly daily intake of BTE may slow down the PD progression as well as delay the onset of neurodegenerative processes in PD.

Animals↗

PubMed2005

Some aspects involving the use of CdTe for finding end-point energies in diagnostic radiology.

We have considered the use of CdTe detectors and commercially available spectroscopy systems for the determination of the end-point energies of diagnostic X-ray devices. A simple technique based upon filtered spectra and simple fitting procedures was used to deduce end-point energies. We observed some unexpected detector-related effects such as significant shifts in the energy calibration at high count rates. When CdTe detectors operate at high counting rates drifts in the DC level, associated with collection rates of the positive charge (holes) can yield a corresponding shift in the spectrum towards lower energies. Only for relatively low counting rates and long detection periods, in excess of 10 min, can end-point energies be obtained with CdTe that reach levels of precision found in recent protocols. High rates also decrease energy resolution and lower the accuracy of recalibrations using characteristic X-rays from the target.

Cadmium Compounds↗

PubMed2004

Perceptions of general environmental problems, willingness to expend federal funds on these problems, and concerns regarding the Los Alamos National Laboratory: Hispanics are more concerned than Whites.

Perceptions about general environmental problems, governmental spending for these problems, and major concerns about the US Department of Energy's Los Alamos National Laboratory (LANL) were examined by interviewing 356 people attending a gun show in Albuquerque, New Mexico. The hypothesis that there are differences in these three areas as a function of ethnicity was examined. We predicted that if differences existed, they would exist for all three evaluations (general environmental problems, government spending, and environmental concerns about LANL). However, this was not the case; there were fewer ethnic differences concerning LANL. Hispanics rated most general environmental problems higher than Whites and rated their willingness to expend federal funds higher than Whites, although all groups gave a lower score on willingness than on concern. Further, the congruence between these two types of ratings was higher for Hispanics than for others. In general, the concerns expressed by subjects about LANL showed few ethnic differences, and everyone was most concerned about contamination. These data indicate that Hispanics attending a gun show are equally or more concerned than others about environmental problems generally but are not more concerned about LANL. The data can be useful for developing future research and stewardship plans and for understanding general environmental problems and their relationship to concerns about LANL. More generally, they indicate that the attitudes and perceptions of Hispanics deserve increased study in a general population.

Conservation of Natural Resources↗

PubMed2004

Mosquito repellent (pyrethroid-based) induced dysfunction of blood-brain barrier permeability in developing brain.

Pyrethroid-based mosquito repellents (MR) are commonly used to protect humans against mosquito vector. New born babies and children are often exposed to pyrethroids for long periods by the use of liquid vaporizers. Occupational and experimental studies indicate that pyrethroids can cause clinical, biochemical and neurological changes, and that exposure to pyrethroids during organogenesis and early developmental period is especially harmful. The neurotoxicity caused by MR has aroused concern among public regarding their use. In the present study, the effect of exposure of rat pups during early developmental stages to a pyrethroid-based MR (allethrin, 3.6% w/v, 8h per day through inhalation) on blood-brain barrier (BBB) permeability was investigated. Sodium fluororescein (SF) and Evan's blue (EB) were used as micromolecular and macromolecular tracers, respectively. Exposure during prenatal (gestation days 1-20), postnatal (PND1-30) and perinatal (gestation days 1-20 + PND1-30) periods showed significant increase in the brain uptake index (BUI) of SF by 54% (P < 0.01), 70% (P < 0.01), 79% (P < 0.01), respectively. This increase persisted (68%, P < 0.01) even 1 week after withdrawal of exposure (as assessed on PND37). EB did not exhibit significant change in BBB permeability in any of the group. The results suggest that MR inhalation during early prenatal/postnatal/perinatal life may have adverse effects on infants leading to central nervous system (CNS) abnormalities, if a mechanism operates in humans similar to that in rat pups.

Aging↗

PubMed2004

Restorative potential of dopaminergic grafts in presence of antioxidants in rat model of Parkinson's disease.

Free radical mediated damage has been reported to contribute significantly towards low survival (5-10%) of grafted dopaminergic neurons, post transplantation. In the present study, an attempt has been made to explore the neuroprotective potential of the combination of two major antioxidants ascorbic acid (AA) and glutathione (GSH) on ventral mesencephalic cells (VMC) and nigral dopamine (DA) neurons when co-transplanted together with VMC in rat model of Parkinson's disease (PD). GSH and AA have been reported to act co-operatively in the conditions of oxidative stress thereby helping in maintaining the cellular GSH/GSSG redox status. Functional recovery was assessed 12 weeks post transplantation, where a significant restoration (p<0.001) in d-amphetamine induced circling behavior (62%), spontaneous locomotor activity (SLA; 64%), dopamine-D2 receptor binding (63%), dopamine (65%) and 3,4-dihydroxy phenyl acetic acid (DOPAC) level (64%) was observed in co-transplanted animals as compared to lesioned and VMC alone grafted rats. VMC and GSH+AA co-transplanted animals exhibited a significantly higher surviving TH-immunoreactive (TH-ir) neurons number (p<0.01), TH-ir fibers outgrowth (p<0.05) in striatal graft and TH-ir neurons in substantia nigra pars compacta (SNpc) (p<0.01), as compared to VMC alone transplanted rats. An attempt was made to further confirm our in vivo observations through in vitro experiments where following in vitro exposure to 6-OHDA, a higher cell survival (p<0.01), TH-ir cell counts (p<0.001) and DA and DOPAC levels (p<0.01) were also observed in 8-day-old VMC culture in presence of GSH+AA as compared to VMC cultured in absence of antioxidants. The results suggest that GSH+AA when co-transplanted with VMC provide higher restoration probably by increasing the survival of grafted VMC and simultaneously supporting nigral TH-immunopositive neurons in rat model of PD.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2004

Olfactory ensheathing cell transplantation restores functional deficits in rat model of Parkinson's disease: a cotransplantation approach with fetal ventral mesencephalic cells.

Different strategies have been worked out to promote survival of transplanted fetal ventral mesencephalic cells (VMCs) using trophic and nontrophic support. Olfactory ensheathing cells (OECs) express high level of growth factors including NGF, bFGF, GDNF, and NT3, which are known to play important role in functional restoration or neurodegeneration. In the present investigation, an attempt has been made to study functional restoration in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD) following cotransplantation of VMC and OECs (cultured from olfactory bulb, OB) in striatal region. The functional restoration was assessed using neurobehavioral, neurochemical, and immunohistochemical approach. At 12 weeks, post-transplantation, a significant recovery (P < 0.001) in D-amphetamine induced circling behavior (73%), and spontaneous locomotor activity (SLA, 81%) was evident in cotransplanted animals when compared with 6-OHDA-lesioned animals. A significant restoration (P < 0.001) in [3H]-spiperone binding (77%), dopamine (DA) (82%) and 3,4-dihydroxy phenyl acetic acid (DOPAC) level (75%) was observed in animals cotransplanted with OECs and VMC in comparison to lesioned animals. A significantly high expression and quantification of tyrosine hydroxylase (TH)-positive cells in cotransplanted animals further confirmed the supportive role of OECs in viability of transplanted dopaminergic cells, which in turn may be helping in functional restoration. This was further substantiated by our observation of enhanced TH immunoreactivity and differentiation in VMC cocultured with OECs under in vitro conditions as compared to VMC alone cultures. The results suggest that cotransplantation of OECs and VMC may be a better approach for functional restoration in 6-OHDA-induced rat model of Parkinson's disease.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2004

Co-transplantation of carotid body and ventral mesencephalic cells as an alternative approach towards functional restoration in 6-hydroxydopamine-lesioned rats: implications for Parkinson's disease.

Exogenous administration of various neurotrophic factors has been shown to protect neurons in animal model of Parkinson's disease (PD). Several attempts are being made to search a tissue source simultaneously expressing many of these neurotrophic factors. Carotid body (CB) contains oxygen-sensitive glomus cells rich in dopamine (DA) and expresses glial cell line-derived neurotrophic factor, brain-derived neurotrophic factor and neurotrophin-3. We have attempted to study the functional restoration following co-transplantation of CB cells and ventral mesencephalic cells (VMC) in a 6-hydroxydopamine-lesioned rat model of PD. A significant recovery (p < 0.001) in d-amphetamine-induced circling behavior (80%) and spontaneous locomotor activity (85%) was evident in co-transplanted animals at 12 weeks post-transplantation as compared to lesioned animals. Similarly, a significant (p < 0.001) restoration was observed in DA-D(2) receptor binding (77%), striatal DA (87%) and 3,4-dihydroxyphenylacetic acid (DOPAC) (85%) levels and nigral DA (75%) and DOPAC (74%) levels. Functional recovery was accompanied by tyrosine hydroxylase (TH) expression and quantification of TH-positive cells by image analysis revealed a significant restoration in TH-immunoreactive (IR) fiber density in striatum, as well as TH-IR neurons in substantia nigra pars compacta in co-transplanted animals over VMC-transplanted animals. The result suggests that co-transplantation of CB cells along with VMC provides better and long-term functional restoration in the rat model of PD, possibly by supporting the survival of newly grafted cells as well as remaining host DA neurons.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2003

Effect of glial cell line-derived neurotrophic factor (GDNF) co-transplantation with fetal ventral mesencephalic cells (VMC) on functional restoration in 6-hydroxydopamine (6-OHDA) lesioned rat model of Parkinson's disease: neurobehavioral, neurochemical and immunohistochemical studies.

Among trophic factors already known, glial cell line-derived neurotrophic factor (GDNF) and other members of its family have potent and specific action on dopaminergic neurons. In the present investigation an attempt has been made to validate the role of GDNF co-transplantation with fetal ventral mesencephalic cells (VMC) on functional viability and restoration using neurobehavioral, neurochemical and immunohistochemical parameters at 6 weeks post-transplantation in 6-hydroxydopamine (6-OHDA) lesioned rat model of Parkinson's disease (PD). A significant restoration (P<0.01) in D-amphetamine induced rotations, spontaneous and apomorphine induced locomotor activity in rats co-transplanted with VMC and GDNF was observed as compared to VMC alone transplanted rats. Level of dopamine (DA), 3,4-dihydroxy-phenyl acetic acid (DOPAC) and dopamine D2 (DA-D2) receptors in the caudate putamen (CPu) were significantly (P<0.001) restored in co-transplanted group as compared to VMC transplanted or GDNF administered animals. The functional viability of transplanted VMC was confirmed by tyrosine hydroxylase (TH) expression and quantification of TH-positive cells by image analysis revealed a significant restoration in TH-IR fibers density as well as TH-IR neurons counts in co-transplanted animals over VMC transplanted animals. Results suggest that co-transplantation of VMC and GDNF may be a better approach towards functional restoration in 6-OHDA lesioned rat model of Parkinson's disease.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2003

Perceptual indicators of environmental health, future land use, and stewardship.

There are important linkages between the health of humans and the environment, restoration of degraded lands, and long-term stewardship of public lands, yet most environmental indicators deal only with assessing the physical and biological aspects of ecosystems. In this article, we examine the ratings of perceptions of several environmental problems for their utility as indicators of environmental quality, and examine perceptions of future land use by people interviewed in Santa Fe, New Mexico, near the Department of Energy's (DOE) Los Alamos National Laboratory (LANL). Overall, people with lower incomes rated environmental problems as more severe than others, were more willing to spend federal funds to solve them, and were consistent in their ratings of severity of environmental problems and their willingness to spend federal funds. Cleaning up LANL and other Department of Energy sites, received the highest rating for expenditure of federal funds. The highest rated future uses for DOE sites were for recreation and for National Environmental Research Parks. People with less education generally gave higher ratings to most future land uses for DOE than did those with more education. However, those with higher education gave higher ratings to nuclear reprocessing, and nuclear material storage. Where there were differences, the people interviewed at Santa Fe rated all environmental problems (except pesticides) as more severe than did those previously interviewed in Albuquerque (located farther from the LANL site), and they were more willing to spend federal funds on these problems. Ratings for all future land uses did not differ between the Santa Fe and Albuquerque respondents. These perception-based indicators show general agreement among people living close and farther away from LANL with respect to cleaning up LANL and the future land uses for the site. These indicators should be considered by regulators, site personnel, and policy makers in future management and land use decisions.

Adult↗

PubMed2003

Prediction of beta-turns from amino acid sequences using the residue-coupled model.

We evaluated the prediction of beta-turns from amino acid sequences using the residue-coupled model with an enlarged representative protein data set selected from the Protein Data Bank. Our results show that the probability values derived from a data set comprising 425 protein chains yielded an overall beta-turn prediction accuracy 68.74%, compared with 94.7% reported earlier on a data set of 30 proteins using the same method. However, we noted that the overall beta-turn prediction accuracy using probability values derived from the 30-protein data set reduces to 40.74% when tested on the data set comprising 425 protein chains. In contrast, using probability values derived from the 425 data set used in this analysis, the overall beta-turn prediction accuracy yielded consistent results when tested on either the 30-protein data set (64.62%) used earlier or a more recent representative data set comprising 619 protein chains (64.66%) or on a jackknife data set comprising 476 representative protein chains (63.38%). We therefore recommend the use of probability values derived from the 425 representative protein chains data set reported here, which gives more realistic and consistent predictions of beta-turns from amino acid sequences.

Algorithms↗

PubMed2003

Prediction of gamma-turns from amino acid sequences.

We predicted gamma-turns from amino acid sequences using the first-order Markov chain theory and enlarged representative data sets corresponding to protein chains selected from the Protein Data Bank (PDB). The following data sets were used for training and deriving the probability values: (1) an initial data set containing 315 protein chains comprising 904 gamma-turns and (2) a later data set in order to include new entries in the PDB, containing 434 protein chains and comprising 1053 gamma-turns. By excluding 93 protein chains that were common to these two training data sets, we generated two mutually exclusive data sets containing 222 and 341 protein chains for testing our predictions. Applying amino acid probability values derived from training data sets on to testing data sets yielded overall prediction accuracies in the range 54-57%. We recommend the use of probability values derived from the data set comprising 315 protein chains that represents more gamma-turns and also provides better predictions.

Amino Acid Sequence↗

PubMed2003

Role of Ca2+ in radiation-induced damage in murine splenocytes.

PURPOSE: To address the links between calcium, peroxidation, cell damage and death and the response of the enzymes involved in free radical metabolism, in splenocytes of mice irradiated with gamma-rays. MATERIALS AND METHODS: Splenocytes of Swiss albino mice were irradiated with various doses (0-7 Gy) of gamma-rays (60Co) at a dose-rate of 0.0575 Gy s(-1). Membrane peroxidation and fluidity were determined by the thiobarbituric acid-reactive substances (TBARS) method, and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), respectively. Apoptosis was analysed by nucleosomal ladder formation and activity of NF-kappaB by electrophoretic mobility shift assay (EMSA). The specific activities of the antioxidant enzymes, lactate dehydrogenase (LDH), levels of nitric oxide (NO*) and glutathione were determined spectrophotometrically. Modulatory effects of Ca2+ were examined at 3 Gy using different concentrations (1, 3 and 5 mM) in the presence or absence of the ionophore A23187. RESULTS: Irradiation of splenocytes resulted in enhanced peroxidative damage. membrane fluidity, apoptosis and DNA binding activity of NF-kappaB. The specific activities of LDH and antioxidant enzymes superoxide dismutase (SOD), DT-diaphorase (DTD), glutathione S-transferase (GST) and levels of glutathione (GSH) and NO* were increased with radiation dose up to 4Gy. Ca2+ augmented the radiation-induced responses. The presence of ionophore A23187 potentiated the modulatory effects of Ca2+. CONCLUSIONS: These findings show that Ca2+ augments radiation damage and is more effective intracellularly. Ca2+, peroxidation, cellular damage and apoptosis are possibly interlinked through signals, as is evident from the increased activity of NF-kappaB and generation of NO*. The enhanced antioxidant status suggests an attempt made by the irradiated cells to maintain their normal functions.

Animals↗

PubMed2003

Perceptions of recreational fishing boat captains: knowledge and effects of fish consumption advisories.

The impacts of fish consumption advisories on recreational and subsistence fishing, particularly in fresh waters, have been examined extensively. By contrast, little attention has focused on organized recreational fishing, such as from party and charter boats, and particularly for salt water fish. We interviewed 93 New Jersey boat captains to determine their knowledge about fish consumption advisories, and whether, in their opinion, clients knew of fish consumption advisories, and whether they thought advisories had an effect on recreational fishing and their businesses. Advisories were ranked by captains as a moderate influence on the success of their business, less so than number of fish caught, strength of the economy, overfishing by commercial boats, and management regulations. Only one boat captain had not heard warnings about eating fish, but what captains said they had heard was mixed in its accuracy and completeness. Clients expect captains to know about fish, and about half of boat captains said clients had asked about the safety of eating fish. Captains who felt advisories were affecting their businesses tended to fish for species without high levels of mercury (except for bluefish) or PCBs, the primary contaminants of concern for state advisories and federal advice. However, these captains worked closer to areas (e.g., Raritan Bay complex and New York Harbor) subject to advisories than did other captains, and were more prone to say that management regulations (e.g., fish size, creel limits, seasons) and marketing and advertising by the industry or state were strong influences on the success of their seasons. Comparing captains who thought advisories had some or great effect (60%) versus those reporting "no effect" (40%), there was no difference in the mean percentage of trips targeting high mercury species such as swordfish and shark. Many captains said they would or might post advisories, but 42% of the boat captains said they would not post consumption warnings if the state provided them. The significant portion (at least 15%) of saltwater fishing supported by these businesses suggests that these captains are an important conduit for future risk communication.

Animals↗

PubMed2002

Exposure of South Carolinians to commercial meats and fish within their meat and fish diet.

There has been considerable interest in the public's exposure to a variety of contaminants through the consumption of wild fish and game, yet there is little information on consumption of commercial meats and fish, or the relationship between commercial and self-caught fish. We conducted a dietary survey in 1999 to estimate exposure levels of 464 individuals from people attending the Palmetto Sportsmen's Classic. Mean consumption was similar for beef, chicken/turkey, and wild-caught fish, and much lower for pork and store-bought fish, and still lower for restaurant fish. There were no ethnic differences in the consumption of most commercial fish and meats, although the differences for chicken approached significance. There were significant ethnic differences in consumption of wild-caught fish. Women ate significantly less of all meat types, except store-bought fish. People over 45 ate less beef than younger people, and people younger than 32 ate significantly more chicken than others. There were no significant differences in consumption patterns as a function of income, except for chicken and wild-caught fish; people with higher incomes ate more chicken than others, and people with lower incomes ate more wild-caught fish than others. When all wild-caught and commercial fish and meats are considered, there are significant differences only for ethnicity and gender. Blacks consume significantly more fish than Whites, and men consume significantly more than women.

Adult↗

PubMed2002

Metal levels in raccoon tissues: differences on and off the Department of Energy's Savannah River Site in South Carolina.

Levels of arsenic, cadmium, chromium, copper, lead, manganese, selenium, and strontium88 were examined in heart, kidney, muscle, spleen and liver of raccoons (Procyon lotor) from four areas on the Department of Energy's Savannah River Site (SRS), including near a former reactor cooling reservoir and a coal ash basin, and from public hunting areas within 15 km of the site. Mercury is mentioned briefly because it is discussed more fully in another paper. We test the hypotheses that there are no differences in metal levels between raccoons on SRS and off the SRS (off-site), and among different locations on the SRS. Although raccoons collected off-site had significantly lower levels of mercury and selenium in both the liver and kidney, there were few consistencies otherwise. There were significantly higher levels of cadmium in liver of on-site compared to off-site raccoons, and significantly higher levels of chromium and strontium88 in kidney of on-site compared to off-site raccoons. Copper and manganese were highest in the liver; cadmium, lead, mercury and selenium were highest in the liver and kidney; chromium was highest in the spleen and muscle; arsenic was highest in the heart, and strontium88 was slightly higher in the kidney than other organs. Where there were significant differences on site, chromium, manganese were highest in raccoon tissues from Steel Creek; arsenic, lead and selenium were highest in the Ash Basin; cadmium was highest at Upper Three Runs; and strontium88 was highest at Upper Three Runs and Steel Creek. The patterns were far from consistent.

Animals↗

PubMed2001

Metals in feathers of sooty tern, white tern, gray-backed tern, and brown noddy from islands in the North Pacific.

Levels of heavy metals are usually higher in adult than young birds because they eat larger, more contaminated prey, or because they have had longer to accumulate metals in their tissues. Further, levels of contaminants are usually less in birds nesting on remote, offshore islands than in birds breeding closer to mainland areas that are urbanized and industrialized. We examined the feather levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in adult sooty terns (Sterna fuscata), gray-backed terns (Sterna lunata), and brown noddy (Anous stolidus, and adult and young white terns (Gygis alba, from Midway Atoll, and in adult and young sooty terns and adult brown noddy from Manana Island, Hawaii (chicks of other terns were not available). We tested and rejected the null hypotheses that metal levels are not significantly different among species, ages, and locations. Despite their small size, adult white terns had the highest levels of lead, arsenic and tin. Brown noddies had the highest levels of cadmium, chromium, manganese, and selenium. Sooty and white terns had the highest levels of mercury. Sooty tern adults had significantly higher levels of cadmium, mercury, and selenium than young, while young had significantly higher levels of arsenic and manganese. White tern adults had significantly higher levels of selenium and tin than young, while young had higher levels of cadmium and mercury than adults. Except for mercury, there were significant inter-location differences within species in all heavy metals. Contrary to expectation, where the differences were great, metals generally were higher in the feathers of terns and noddies from Midway than from Manana.

Age Factors↗