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Biomedical subjects

J A Jackson

Publications and source records attributed to J A Jackson.

At least 37 records · Page 2Linked to original sources

Changes in body temperature and urinary cortisol after routine immunization in babies with intrauterine growth retardation.

AIM: To investigate whether infants with intrauterine growth retardation (IUGR) experience different changes in temperature and cortisol excretion after routine immunization compared with normal healthy infants. METHODS: Overnight deep body temperature and urinary cortisol to creatinine ratios were measured on the night after immunization and a control night in normal and IUGR infants. RESULTS: In 60 normal infants, first vaccination at about 10 wk of age led to a significant increase in minumum overnight temperature compared to the control night, mean rise 0.25 degrees C (95% CI, 0.12 to 0.38). In 35 IUGR infants the mean rise in temperature between immunization night and control night was 0.35 degrees C (95% CI, 0.15 to 0.55). The increases in minimum temperature did not differ significantly between the normal and IUGR infants (p = 0.11). Cortisol to creatinine ratios measured from overnight urine samples showed that 23 IUGR infants had consistently higher levels than 39 normal infants: control night medians 34 and 15 (p=0.01) and immunization night medians 56 and 26 (p = 0.02), respectively. However, the percentage increase did not differ significantly between the IUGR infants and the normal infants. A smaller number of second immunizations were studied, but no significant differences were found. CONCLUSION: These results suggest that although the impact of immunization is the same for IUGR and normal infants, because IUGR infants are less mature and at greater stress before immunization, the absolute levels that they experience after immunization are higher than those for normal infants.

Body Temperature↗

Safety risk analysis of an innovative environmental technology.

The authors describe a decision and risk analysis performed for the cleanup of a large Department of Energy mixed-waste subsurface disposal area governed by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). In a previous study, the authors worked with the site decision makers, state regulators, and U.S. Environmental Protection Agency regional regulators to develop a CERCLA-based multiobjective decision analysis value model and used the model to perform a screening analysis of 28 remedial alternatives. The analysis results identified an innovative technology, in situ vitrification, with high effectiveness versus cost. Since this technology had not been used on this scale before, the major uncertainties were contaminant migration and pressure buildup. Pressure buildup was a safety concern due to the potential risks to worker safety. With the help of environmental technology experts remedial alternative changes were identified to mitigate the concerns about contaminant migration and pressure buildup. The analysis results showed that the probability of an event with a risk to worker safety had been significantly reduced. Based on these results, site decision makers have refocused their test program to examine in situ vitrification and have continued the use of the CERCLA-based decision analysis methodology to analyze remedial alternatives.

Decision Support Techniques↗

The effect of cation-anion difference on calcium requirement, feed intake, body weight gain, and blood gasses and mineral concentrations of dairy calves.

Our objective was to examine the effects of two diets with different cation-anion differences on Ca requirements in the growing calf. Holstein calves (n = 48, 24 males) were blocked at 56 to 70 d after birth (80+/-10 kg of body weight) according to sex and birth date and assigned randomly in a 2 x 3 factorial arrangement of dietary treatments containing cation-anion differences as meq (Na + K) - (Cl + S)/kg of diet dry matter and Ca content of 1) 0 and 0.35%, 2) 0 and 0.50%, 3) 0 and 0.65%, 4) 200 and 0.35%, 5) 200 and 0.50%, and 6) 200 and 0.65%. Feed intake and average daily gain did not differ among treatment groups. Plasma pH and Ca were unaffected by dietary Ca content or dietary cation-anion difference. Plasma Cl and P decreased linearly with increasing Ca content in the diet. Plasma HCO3 increased linearly with increased dietary Ca content. Plasma HCO3 and partial pressure of CO2 were higher in calves fed the 200 compared with calves fed the 0 cation-anion difference diets. Plasma Cl was, however, lower in calves fed the 200 compared with calves fed the 0 meq diets. An interaction of Ca content and dietary cation-anion difference was detected for plasma P content. Urinary pH increased linearly with increasing dietary Ca content. Calves fed the 200 meq dietary cation-anion difference had higher urinary pH values than those fed the 0 meq diet. Urinary P excretion was not altered by dietary cation-anion difference or Ca content of the diet. Calves fed the 0 meq diet had higher urinary cocnentrations of Ca and Cl when compared with those fed the 200 meq diet. Bone ash, P, Ca, Mg, and K content of the 10th rib were not affected by dietary treatments. Breaking strength of the seventh and ninth ribs increased quadratically with increasing dietary Ca content. Dietary cation-anion difference had no effect on the breaking strength of the seventh and ninth ribs. Varying the dietary cation-anion difference from 0 to 200 meq/kg of dietary dry matter had no effect on Ca requirement of the growing calf.

Animals↗

Influence of supplemental chromium on concentrations of liver triglyceride, blood metabolites and rumen VFA profile in steers fed a moderately high fat diet.

This study evaluated the effects of supplemental Cr on liver triglycerides and blood metabolites in Holstein steers fed a moderately high fat (approximately 5.6% of dry matter) diet. Fourteen Holstein steers were blocked by BW and randomly assigned to a basal diet (control) or control diet supplemented with 0.8 mg/kg of Cr as chromium picolinate. Supplemental Cr had no effect on dry matter intake, average daily gain, serum glucose, insulin, cholesterol, and molar proportions of ruminal volatile fatty acids (VFA). Steers fed the diet supplemented with chromium picolinate had smaller concentrations of serum triglycerides at wk 3, plasma beta-hydroxybutyrate concentrations at wk 6, and liver triglycerides at wk 9. An in vitro mixed ruminal microorganism fermentation study was conducted to examine the effect of Cr on in vitro VFA production. Ruminal fluid from animals fed fescue hay and 1.1 kg of concentrate twice daily was added into a mixture containing 5 g of concentrate diet formulated to contain one of five concentrations of Cr (0, 0.2, 0.4, 0.8, or 1.6 mg/kg of Cr). The culture was incubated for 12 or 24 h. The molar proportion of propionate decreased, whereas butyrate and isobutyrate increased linearly with increasing Cr content at 12 h of incubation. Molar proportion of valerate alone increased linearly with increasing Cr content at 24 h of incubation. A second in vitro study evaluated the supplementation of Cr at concentrations of 0, 0.8, 1.6, 3.2, 6.4, 12.8, or 25.6 mg/kg. Molar proportions of acetate, propionate, and isovalerate, and total VFA production responded quadratically with increasing Cr content at 24 h. Results suggest that supplemental Cr may alter systemic lipid metabolism. In vitro fermentation altered VFA production with graded concentration of Cr and was not toxic to ruminal microorganisms at concentrations up to 25.6 mg/kg.

3-Hydroxybutyric Acid↗

Effects of NutriDense and waxy corn hybrids on the rumen fermentation, digestibility and lactational performance of dairy cows.

The objectives of this study were to determine the effects of NutriDense and waxy corn hybrids as silage and grain sources on milk yield, milk composition, digestibility of dietary components, and rumen characteristics. Six multiparous (intact) and six primiparous (ruminally cannulated) Holstein cows were assigned at 72 to 90 d of lactation to a 3 x 6 Latin rectangle design experiment to treatment of: 1) control diet, 2) NutriDense corn diet, and 3) waxy corn diet. Diets consisted of 10.9% alfalfa silage, 32.8% corn silage, 27.9% cracked corn grain, and 28.4% other ingredients (DM basis). Milk, FCM, and milk fat and protein yields were higher for cows fed the waxy diet than those fed the control diet. Milk protein percentage tended to be higher for cows fed the control and waxy diets than those fed the NutriDense diet. Dry matter intake tended to be higher for cows fed the waxy diet than the NutriDense diet. Apparent DM, OM, CP, ADF, NDF, and gross energy digestibilities were similar among dietary treatments, while apparent starch digestibility was higher for the waxy corn than for the NutriDense corn. Rumen NH3-N concentration was higher for cows fed the NutriDense diet than for those fed the control and waxy diets. The proportion of ruminal propionate was higher for the waxy diet than the control diet. NutriDense and waxy corn hybrids can be effective substitutes for conventional yellow dent corn hybrids in lactating dairy cow rations.

Ammonia↗

Rerating capacity of a constructed wetland treatment system.

The 482-hectare (ha) City of Orlando (Florida) Easterly Wetlands (OEW) was designed to reduce nutrient concentrations in 0.90 m3/s of wastewater from the Iron Bridge Regional Water Reclamation Facility. Design influent nutrient concentrations were 6 mg/L total nitrogen (TN) and 0.75 mg/L total phosphorus (TP). Actual TN and TP concentrations have been less than design, averaging 2.6 mg/L and 0.29 mg/L, respectively from January 1988 through December 1999. If influent concentrations remain at these levels, the OEW may have the potential to treat significantly higher flows since less than 20% of the total area was utilized for nutrient reduction. To test this theory, a capacity study was performed for approximately nine months in 1997 and 1998. Simulated flows of approximately 1.26 m3/s, 1.66 m3/s, and 1.93 m3/s were tested. It was found that approximately 15% of the area was utilized for nutrient reduction during the 1.26 m3/s simulation, 35% in the 1.66 m3/s, and 1.93 m3/s simulations. Based on these testing results, an application was submitted to the state in early 2000 to increase the permitted capacity to 1.57 m3/s.

Biodegradation, Environmental↗

Characterization of a Rhodobacter capsulatus reaction center mutant that enhances the distinction between spectral forms of the initial electron donor.

A large scale mutation of the Rhodobacter capsulatus reaction center M-subunit gene, sym2-1, has been constructed in which amino acid residues M205-M210 have been changed to the corresponding L subunit amino acids. Two interconvertable spectral forms of the initial electron donor are observed in isolated reaction centers from this mutant. Which conformation dominates depends on ionic strength, the nature of the detergent used, and the temperature. Reaction centers from this mutant have a ground-state absorbance spectrum that is very similar to wild-type when measured immediately after purification in the presence of high salt. However, upon subsequent dialysis against a low ionic strength buffer or the addition of positively charged detergents, the near-infrared spectral band of P (the initial electron donor) in sym2-1 reaction centers is shifted by over 30 nm to the blue, from 852 to 820 nm. Systematically varying either the ionic strength or the amount of charged detergent reveals an isobestic point in the absorbance spectrum at 845 nm. The wild-type spectrum also shifts with ionic strength or detergent with an isobestic point at 860 nm. The large spectral separation between the two dominant conformational forms of the sym2-1 reaction center makes detailed measurements of each state possible. Both of the spectral forms of P bleach in the presence of light. Electrochemical measurements of the P/P+ midpoint potential of sym2-1 reaction centers show an increase of about 30 mV upon conversion from the long-wavelength form to the short-wavelength form of the mutant. The rate constant of initial electron transfer in both forms of the mutant reaction centers is essentially the same, suggesting that the spectral characteristics of P are not critical for charge separation. The short-wavelength form of P in this mutant also converts to the long-wavelength form as a function of temperature between room temperature and 130 K, again giving rise to an isobestic point, in this case at 838 nm for the mutant. A similar, though considerably less pronounced spectral change with temperature occurs in wild-type reaction centers, with an isobestic point at about 855 nm, close to that found by titrating with ionic strength or detergent. Fitting the temperature dependence of the sym2-1 reaction center spectrum to a thermodynamic model resulted in a value for the enthalpy of the conformational interconversion between the short- and long-wavelength forms of about -6 kJ/mol and an entropy of interconversion of about -35 J/(K mol). Similar values of enthapy and entropy changes can be used to model the temperature dependence in wild-type. Thus, much of the temperature dependence of the reaction center special pair near-infrared absorbance band can be described as an equilibrium shift between two spectrally distinct conformations of the reaction center.

Amino Acid Sequence↗

Modified inter-simple sequence repeat PCR protocol for use in conjunction with the LI-COR Gene ImagIR2 DNA analyzer.

Inter-simple sequence repeat (inter-SSR) PCR was assessed for use in variety testing of chrysanthemum. This method was modified to allow detailed analysis of DNA profiles on a LI-COR Gene ImagIR2 DNA analyzer system. Protocols for unlabeled PCR were unsuccessful in producing labeled products when using infrared (IR) dye-labeled primers. Various modifications to the known protocols were investigated: (i) different ratios of labeled to unlabeled primer; (ii) various annealing temperatures; (iii) the use of an IR genotyping kit; (iv) end labeling; and (v) direct incorporation and cycle labeling. Successful amplification using labeled primers only occurred when two consecutive reactions were performed. The first PCR was performed using standard protocols for unlabeled reactions. The second PCR used a dilution of these reaction products as a template and 50% IR-labeled and unlabeled primer. The complete procedure leading to a high-resolution analysis of inter-SSR PCR products on a LI-COR system is reported for the first time. This system allows high-throughput fingerprinting with the potential for applications on a commercial scale.

Chrysanthemum cinerariifolium↗

Relationship of impression cytology and tear ferning to reports of dry eye.

PURPOSE: This study investigated whether there is a significant correlation between mild-to-moderate patient reports of dry eye and results on the tear ferning and impression cytology tests. METHODS: One hundred and four subjects were surveyed for presence or absence of dry eye symptoms. Membrane impression cytology and tear ferning were performed on each subject. Impression cytology specimens were evaluated for the presence of goblet cells, presence of epithelial cell sheets, and epithelial cell morphology. Tear specimens were evaluated for quality of ferning. RESULTS: A significant correlation was found between subjective dry eye symptoms and impression cytology results (cc = 0.28, p = 0.003). However, there was no statistically significant correlation between dry eye symptoms and tear fern results (cc = 0.072, p = 0.458). CONCLUSIONS: Impression cytology appeared to be a better predictor of mild-to-moderate dry eye symptoms than tear ferning.

Adult↗

Analysis of parasite host-switching: limitations on the use of phylogenies.

Even the most generalist parasites usually occur in only a subset of potential host species, a tendency which reflects overriding environmental constraints on their distributions in nature. The periodic shifting of these limitations represented by host-switches may have been an important process in the evolution of many host-parasite assemblages. To study such events, however, it must first be established where and when they have occurred. Past host-switches within a group of parasites are usually inferred from a comparison of the parasite phylogeny with that of the hosts. Congruence between the phylogenies is often attributed to a history of association by descent with cospeciation, and incongruence to host-switching or extinction in 'duplicated' parasite lineages (which diverged without a corresponding branching of the host tree). The inference of host-switching from incongruent patterns is discussed. Difficulties arise because incongruence can frequently be explained by different combinations of biologically distinct events whose relative probabilities are uncertain. Also, the models of host-parasite relationships implicit in historical reconstructions may often not allow for plausible sources of incongruence other than host-switching or duplication/extinction, or for the possibility that colonization could, in some circumstances, be disguised by 'false' congruence.

Adaptation, Physiological↗

Opioids disrupt Ca2+ homeostasis and induce carbonyl oxyradical production in mouse astrocytes in vitro: transient increases and adaptation to sustained exposure.

Pharmacologically distinct subpopulations of astroglia express mu, delta, and/or kappa opioid receptors. Activation of mu, delta, or kappa opioid receptors can destabilize intracellular calcium ([Ca2+]i) in astrocytes leading to cellular hypertrophy and reactive injury. To assess whether acute or sustained opioid exposure might adversely affect astroglial function by disrupting Ca2+ homeostasis or by producing reactive oxygen species, fura-2 and a novel fluorescent-tagged biotin-4-amidobenzoic hydrazide reagent, respectively, were used to detect [Ca2+]i and carbonyl oxidation products within individual murine astrocytes. Acute (3 h) exposure to mu; (H-Tyr-Pro-Phe (N-Me) -D-Pro-NH2; PLO17), delta ([D-Pen2, D-Pen5]-enkephalin), and kappa (trans-(+/-)-3, 4-dichloro-N-methyl-N-[2-(1-pyrr olidinyl) cyclohexyl] benzeneacetamide methanesulfonate; U50,488H) opioid agonists caused significant mean increases in [Ca2+]i and in the levels of oxidative products in astrocytes. In contrast, following 72 h of continuous opioid exposure, [Ca2+]i and carbonyl levels returned to normal, irrespective of opioid treatment. These preliminary findings indicate that opioids initially destabilize [Ca2+]i and increase reactive oxygen species in astrocytes; however, astrocytes later recover and adapt to sustained opioid exposure.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

Effects of temperature on oviposition rate in Protopolystoma xenopodis (Monogenea: Polystomatidae).

Protopolystoma xenopodis is an oviparous monogenean occurring as an adult in the urinary bladder of the African clawed toad, Xenopus laevis. Egg production was monitored in two groups of infected hosts exposed to decreasing environmental temperatures. Despite possible upward trends in reproductive capacity with parasite age, oviposition rate was severely depressed at lower temperatures. In one experiment, egg production was monitored in a sample of seven hosts at 2 degrees C intervals between 20 and 8 degrees C. Overall mean egg production rate showed a consistent decline from 11.9 eggs/worm/day (e/w/d) at 20 degrees C (days 1-10) to 0.9 e/w/d at 8 degrees C (days 115-124). In a second experiment (n = 11 hosts) oviposition rate was recorded at the same intervals between 20 and 6 degrees C and then hosts were returned to 20 degrees C. Overall mean egg production rate decreased consistently from 4.1 e/w/d at 20 degrees C (days 1-10) to 0.2 e/w/d at 6 degrees C (days 124-131), at which temperature all infections continued to produce eggs. When parasites were then returned to 20 degrees C (141-150 days), mean oviposition rate at this temperature (12.7 e/w/d) was found to have increased by 310% from the start of the experiment (130 days earlier) and by 6350% from production at 6 degrees C (9 days earlier). P. xenopodis has been introduced to South Wales, U.K. and present results show that it could produce eggs here through almost all of the year. However, a massive annual reduction in the reproductive output of this parasite in the U.K., compared with that in natural sites, is predicted.

Age Factors↗

Incompatibility of Protopolystoma xenopodis (Monogenea: Polystomatidae) with an octoploid Xenopus species from southern Rwanda.

Protopolystoma xenopodis is an oviparous monogenean occurring as an adult in the urinary bladder of the clawed toad Xenopus laevis. Oncomiracidia invade the host's kidneys where juveniles develop, subsequently migrating to the definitive site. In central Africa, the tetraploid X. laevis occurs in sympatry with octoploid congeners, including Xenopus wittei, believed to be the hybrid derivatives of X. laevis- and Xenopus fraseri-like parental lineages. Twenty laboratory-raised, naive specimens of an X. wittei-like species from southern Rwanda were each exposed to 30 embryonated P. xenopodis eggs (at 20 degrees C) and screened for parasite egg production until 9 months post-exposure. These toads failed to support the development of gravid parasites (comparable experimental procedures produce at least 35% prevalence of patent infection in the natural host X. laevis). Further X. wittei aff. (n = 26) and X. laevis (n = 17) were exposed to P. xenopodis oncomiracidia and dissected at variable times post-exposure: larvae were able to invade the kidneys of X. wittei aff. and began feeding and morphological development. Severe mortality of juveniles occurred in both natural and unnatural hosts between invasion and 39 days post-exposure. However, while small numbers of parasites persisted in X. laevis, no stages were found in X. wittei aff. beyond 39 days. Present data demonstrate the incompatibility of P. xenopodis with X. wittei aff. and are consistent with a hypothesis that specificity in Protopolystoma-Xenopus systems is determined primarily by the ability of juveniles to complete development in the host's kidneys.

Animals↗

Reproductive interference in concurrent infections of two Protopolystoma species (Monogenea: Polystomatidae).

The prevention of interspecific reproductive interference is one possible explanation for spatial niche divergence between congeneric monogeneans. However, there is little direct evidence that reproductive interactions with other species are potentially deleterious to the majority of parasitic platyhelminths. Xenopus fraseri-like clawed toads from lowland rainforest in eastern Democratic Republic of Congo are infected by two species of polystomatid monogenean, Protopolystoma fissilis and Protopolystoma ramulosus. Both occur as adults in the host urinary bladder, and exhibit identical copulatory structures and similar body sizes. The small area of the habitat in relation to parasite body size makes close proximity inevitable in concurrent infections. Eggs were collected from five naturally infected hosts: two of these harboured concurrent infections, and three were infected with P. fissilis only. Eggs from concurrent infections showed reduced viability (57.6% embryonation, n = 413) compared with those from P. fissilis-only infections (85.2%, n = 439). This effect may be due to some form of reproductive interference, possibly failure to develop following interspecific cross-fertilisation.

Animals↗

Correlation of parasite speciation and specificity with host evolutionary relationships.

Protopolystoma (Monogenea, Polystomatidae) is strictly specific to the anuran amphibian genus Xenopus. The host group is characterised by a polyploid series in which chromosome numbers reflect diploid, tetraploid, octoploid and dodecaploid constitutions; the series is considered to have evolved through interspecies hybridisation and genome duplication. This study correlates information on host evolutionary relationships with patterns of parasite speciation and host specificity. Protopolystoma is restricted to one subgenus (Xenopus) with multiples of 36 chromosomes, and is absent from the subgenus Silurana (with multiples of 20 chromosomes). Molecular, biochemical and karyotype evidence distinguishes three subgroups within Xenopus. Representative species from each subgroup, Xenopus muelleri, Xenopus fraseri and Xenopus laevis, have been examined for polystomatid infection. Two species of Protopolystoma occur in each of these host species. In X. muelleri, the two Protopolystoma species reflect parasite co-speciation corresponding with the divergence of two sibling host species. Xenopus fraseri and X. laevis (both with 2n = 36 chromosomes) are implicated in the hybrid origin of two octoploid species, Xenopus wittei and Xenopus vestitus (both 2n = 72). The relationships of the Protopolystoma species in these Xenopus taxa reflect this presumed ancestry. Xenopus wittei carries two species of Protopolystoma, one shared with X. fraseri and the other shared with X. laevis. Xenopus vestitus carries a single species of Protopolystoma which is shared with X. laevis but there is no "heirloom" which reflects its hybrid origin involving X. fraseri. In addition to these shared parasite species which may reflect shared host genes, X. fraseri and X. laevis each carry separate species-specific Protopolystoma which do not occur in other Xenopus species even where there is evidence of common genetic information (as in the allopolyploid wittei and vestitus). This case study may be interpreted as indicating a powerful influence of host genetic factors on susceptibility to infection, host-specificity, and parasite speciation.

Animals↗

Mutual exclusion of congeneric monogenean species in a space-limited habitat.

Adults of the monogenean genus Protopolystoma infecting Xenopus species occur in an extremely space-limited habitat, the urinary bladder. Xenopus wittei, from a population in Rwanda naturally infected with Protopolystoma fissilis and Protopolystoma simplicis, were exposed to reinfection in captivity (for 1-3 months post-capture) and then monitored in the laboratory for up to 5 months in transmission-free conditions. The two parasites co-occurred in individual bladders less frequently than expected if they were dispersed randomly. Distribution of bladder infections was significantly non-independent (n = 157) and gravid worms of both species were never found in the same host. This pattern might be explained by interference competition between the parasites or by genetic differences in susceptibility within the host species, which is of allopolyploid origin. Other distributional data for sympatric polystomatid species pairs, including P. fissilis and P. ramulosus, show concurrent infections at frequencies consistent with random distributions (i.e. no evidence of interspecific competition or variability in species-specific susceptibility of the hosts). Interference between P. fissilis and P. simplicis (assuming host genetic factors are not involved) may therefore result from a mechanism specific to this species pair. Observations on infection turnover in captive hosts suggest that loss of adult worms may be related to the arrival of juveniles (of either species) in the urinary bladder. Ectopic infection of the host urinary ducts by adult and subadult P. fissilis was observed in some single-species infestations and may be density related. However, the use of an ectopic-site 'refugium' has never been observed in concurrent polystomatid infections.

Animals↗

Use of statistical process control for surveillance of pulmonary dysfunction in groups in the workplace.

Workplace surveillance is an essential feature of an effective occupational health program. Unfortunately, many health care organizations are beginning to collect large quantities of clinical information without much thought to subsequent application. In this paper, we propose a screening technique to help manage this situation. Specifically, we advocate "control charts for fraction non-conforming" for use in the medical surveillance of work areas. A military installation in the mid-western United States with 63 work areas is analyzed using up to seven years worth of spirometry data. Based on the results of 6 separate tests, a classification of normal or abnormal was made for each individual and the percent of abnormalities by area and year was calculated. The results were analyzed via control charts and contrasted to a preset percentage method. Cigarette smoking was then controlled for in the analysis to account for abnormalities that may be occupationally related versus personal habits. We demonstrate the utility of control charts for the compact display of surveillance data and show how it can aid in the analysis of an extremely complex health care concern. A recommendation is made for managing a surveillance program using spirometry and control charts and supported by follow-on investigation of two areas flagged as abnormal by the procedure.

Adult↗