Benquerencia (La Serena - Spain) rock art: An integrated spectroscopy analysis with FTIR and Raman

La Serena region is a large plateau with open landscapes bounded in the south by a mountain chain formed by the Benquerencia, Tiros and La Rinconada Sierras. There are more than 300 painted and engraved sites in the region. Cueva Grande, Cueva de En medio and Cueva Pequeña are three Schematic rock art shelters located in the municipality of Benquerencia de la Serena, Badajoz, Spain. Over their panels have been documented more than a hundred of painted schematic figures (anthropomorphic figures, eye-shape figures and symbols) (Neolithic - Copper Age). Paintings are monochromatic with red or black coloration. A total of 13 samples (10 red and 3 black samples) from different panels were collected and analyzed using micro-Raman spectroscopy and ATR-FTIR. Micro-Raman spectroscopy was able to characterize the main mineral component, respectively hematite for the red figures and charcoal for the black paintings. ATR-FTIR was useful to possible ochre and possible organic identification. These latest results are particularly important for understanding manufacturing processes and addressing conservation problems.

Microcosm evaluation of the impact of oil contamination and chemical dispersant addition on bacterial communities and sediment remediation of an estuarine port environment

AIM

To evaluate the interactive effects of oil contamination and chemical dispersant application on bacterial composition and sediment remediation of an estuarine port environment.

METHODS AND RESULTS

A multifactorial controlled microcosm experiment was set up using sediment cores retrieved from an estuarine port area located at Ria de Aveiro lagoon (Aveiro, Portugal). An oil spill with and without chemical dispersant addition was simulated. Sediment oil hydrocarbon concentrations and benthic bacterial community structure were evaluated by GC-MS and 16S rRNA high-throughput sequencing respectively. Although initially (first 10 days) chemical dispersion of oil enhanced the concentrations of the heavier polycyclic aromatic hydrocarbons and of the C₂₂ -C₃₀ alkane group, with time (21 days), no significant differences in hydrocarbon concentrations were detected among treatments. Moreover, no significant changes were detected in the structure of sediment bacterial communities, which mainly consisted of operational taxonomic units related to hydrocarbon-contaminated marine environments. We hypothesize that the environmental background of the sampling site preconditioned the communities' response to additional contamination.

CONCLUSION

This experimental microcosm study showed that the chemical dispersion of oil did not influence sediment remediation or bacterial community composition.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our study showed that chemical dispersion of oil may not improve the remediation of port sediments. Further studies are needed to investigate the impact of chemical dispersants in combination with bioremediation strategies on the process of sediment remediation in port areas.

The impact of facial lipoatrophy treatment with polymethyl methacrylate in AIDS patients as measured by four quality-of-life questionnaires

Life-expectancy increased in patients infected with HIV/AIDS with the advent of highly active antiretroviral therapy (ART). Facial lipoatrophy is a common complication in these patients, eventually leading to stigma, segregation and a negative impact in quality of life (QOL). We measured the impact of the treatment of facial lipoatrophy with polymethyl methacrylate (PMMA) in the QOL of patients with HIV/AIDS by using four questionnaires that address QOL. Forty consecutive patients on ART referred for facial lipoatrophy treatment were enrolled in this study. The first 20 were allocated to the intervention group and were treated with tissue augmentation with PMMA. The other 20 were allocated to the control group, which received treatment only after six months. At baseline, four questionnaires were applied to all patients in both groups and again after six months. The variation in scores within the control group for all domains of all four instruments was significantly better when compared with that within the control group. We detected improvement in the QOL of patients with HIV/AIDS and facial lipoatrophy when they were treated with PMMA.

European Immunization Week 2008 - time for reflection

This week’s edition of Eurosurveillance is dedicated to European Immunization Week 2008, which will take place from 21 to 27 April. In 2005, the World Health Organization (WHO) organised the first European Immunization Week (http://www.euro.who.int/vaccine/eiw/20050608_1) to increase vaccination coverage by raising awareness about the importance of immunisation, with a special focus on reaching vulnerable and hard-to-reach population groups. During the week, each participating country implements activities to inform and engage key target groups using the slogan “prevent-protect-immunise” and focuses on critical challenges regarding immunisation in their country.

Fetal hemangiopericytoma with an associated cerebral anomaly

We report the first case of infantile hemangiopericytoma explored prenatally by fetal ultrasonography and magnetic resonance imaging (MRI). It was associated with a developmental cerebral anomaly identified on MRI. The largest lesions of the multifocal hemangiopericytoma were located in the soft tissue adjacent to the left temporal bone, and smaller lesions were found in the lumbar area and in the retroperitoneum. MRI showed no connection between the tumor and the fetal brain but there was anomalous cerebral gyration in the region and the Sylvian fissure beneath the tumor was enlarged. The pregnancy was terminated because of the severe brain anomalies and postmortem examination confirmed the prenatal findings. Microscopic analysis of the tumor tissue showed branching vessels which are typical of hemangiopericytoma. The lesions in our case occurred in association with macrosomia with visceromegaly detected at autopsy, suggesting a possible role of tumor suppressor genes.

Removal of organic contaminants from soils by an electrokinetic process: the case of atrazine. Experimental and modeling

The atrazine behaviour in soils when submitted to an electric field was studied and the applicability of the electrokinetic process in atrazine soil remediation was evaluated. Two polluted soils were used, respectively with and without atrazine residues, being the last one spiked. Four electrokinetic experiments were carried out at a laboratory scale. Determination of atrazine residues were performed by enzyme-linked immunosorbent assay (ELISA). The results show that the electrokinetic process is able to remove efficiently atrazine in soil solution, mainly towards the anode compartment: Estimations show that 30-50% of its initial amount is removed from the soil within the first 24h. A one-dimensional model is developed for simulating the electrokinetic treatment of a saturated soil containing atrazine. The movement of atrazine is modelized taking into account the diffusion transport resulting from atrazine concentration gradients and the reversed electro-osmotic flow at acidic soil pH.

Acute Ischemic Hepatitis in Aortocaval Fistula

OBJECTIVES

To characterise liver dysfunction in patients with aortocaval fistula.

DESIGN

Retrospective study.

MATERIALS

All four patients operated on for aortocaval fistula between 1999 and 2003. Three were males with ruptured abdominal aortic aneurysm (AAA). One was a female who underwent lumbar disk surgery. Four patients operated on for ruptured AAA were used as controls.

METHODS

Measurement of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatinine from the preoperative period until full recovery.

RESULTS

The median delay between the presumed formation of the fistula and surgery was 2 days (range 1-3 days). High levels of AST, ALT and LDH were observed in all patients, starting from the preoperative period, reaching the maximum on the first two postoperative days and normalising thereafter. Median peak values were: AST=4256 IU/l (range 816-7779), ALT=2487 IU/l (range 960-5645) and LDH=15165 IU/l (range 3122-32361). Serum creatinine also sustained alterations with a similar time course. Median peak values were: 256 micromol/l (range 230-468). All the patients survived.

CONCLUSIONS

Acute ischemic hepatitis appears to be a consistent or, at least, a common complication of aortocaval fistula. Although a concern during the perioperative period, its course is benign and fully resolves upon successful surgery.

[Pitfalls of hematopoietic growth factors on MR images]

We report the effects of hematopoietic growth factors on MR signal intensity of bone marrow in 2 children undergoing chemotherapy for musculoskeletal malignancies. The two patients with initially fatty marrow had signal intensity changes: diffuse decreased signal of the distal femoral metaphysis and patchy areas in the diaphysis of both tibia and fibula, simulating metastases. These changes coincided with dramatic increase in neutrophil counts. Technetium 99 skeletal scintigraphy was normal. After a three year follow-up the patients are in good health.

The detection of constancy amidst change in children: a dissociation of preattentive and intentional processing

This study examined whether 7-9-year-old children preattentively build memories of constancy for individual stimulus features, and if these representations are affected by variability of other stimulus features. This was achieved by looking at the mismatch negativity (MMN) event-related potential to a duration deviant occurring in a stimulus environment in which one or two other features constantly changed. Performance data were also collected, to look at the correspondence between the effects of this manipulation on preattentive and intentional deviance detection. MMN data indicated that the children built a preattentive feature-based memory of constancy that was not affected by the number of varying features. In contrast, intentional deviance detection was considerably impaired by the introduction of feature variability. This dissociation is at variance with previous studies that usually report close association between MMN and behavior.

Spatiotemporal maturation of the central and lateral N1 components to tones

This paper examines maturational changes in the spatiotemporal features of central and lateral N1 components of the auditory evoked potentials (AEPs) to tone stimuli presented with a long stimulus onset asyncrony (SOA; 4200 ms) using the scalp current density (SCD) technique. A group of typically developing children ranging from 6 to 12 years of age and a group of adults were studied. Recently studies have begun to explore the topography of these components in children. These studies, however, often used rapidly presented stimuli and did not elicit observable central N1s in the younger children. Our stimuli elicited both central and lateral N1s. Peak latencies of both components decreased with age. Peak amplitude also decreased with age for the lateral N1 but not for the central N1. Consequently, the difference between the lateral N1 and the central N1 amplitudes (or the ratio of lateral N1 amplitude to central N1 amplitude) also decreased with age, dramatically altering the morphology of the elicited AEP waveforms. Topography of the lateral N1 did not change with age. The location of maximal activation for the central N1 appeared to move more medially with age but this 'apparent' movement is probably due to the decreasing impact of the partially overlapping lateral N1 component whose amplitude is significantly smaller in adults than in children.

Mismatch negativity in children and adults, and effects of an attended task

Attention has been shown to modulate the amplitude of the mismatch negativity (MMN) elicited by a small deviation in auditory stimuli in adults. The present study examined the effects of attention and deviant size on MMN amplitude in children. Children and adults were presented with sequences of tones containing standards (1000 Hz) and three deviants varying in degree of deviance from the standard (1050, 1200, and 1500 Hz). Tones were presented in three conditions: (1) while participants ignored them; (2) while participants listened to them and responded to all three deviants; and (3) while participants again ignored them. We found that the MMNs elicited by the hard deviant (1050 Hz) were larger when the children were actively discriminating the stimuli than when they were ignoring them. However, the MMNs elicited by the easy and medium deviants (1500 and 1200 Hz, respectively) in the children and by all three deviants in the adults were not affected by attention.

Sinus pericranii: advantages of MR imaging

Sinus pericranii is a rare vascular anomaly involving an abnormal communication between the extracranial and intracranial circulations. A 3-year-old girl presented with a 2 x 2-cm, midline soft-tissue mass at the vertex. Plain skull films and CT using bone windows showed erosion of the parietal bones. MRI confirmed the clinical diagnosis by identifying communication of the vascular mass with the intracranial dural venous sinus. The advantages of MRI are discussed.

Effect of frequency separation and stimulus rate on the mismatch negativity: an examination of the issue of refractoriness in humans

Refractoriness of the generators of the mismatch negativity (MMN) was examined in two experiments in which two deviant tones occurred in a row. In Experiment 1, the size of the MMN elicited by the first deviant was manipulated by using deviants that were close to or far from the standard in frequency. In Experiment 2, the time between two identical deviants was varied. It was found that neither the size of the MMN elicited by the first deviant, nor the time between two deviants, affected the amplitude of the MMN elicited by the second deviant. It was concluded that refractoriness played no role in the amplitude of the MMN for the parameters used.

The development of auditory attention in children

In this paper we review the development of four components of auditory attention: arousal, orienting, selective attention and sustained attention. We focus especially on the processes responsible for the selection of specific stimuli for further processing because these are essential for learning and development. Although much work still needs to be done, there is evidence of developmental change in some of the components of attention, especially early in infancy. Later developmental improvements seem to be primarily attributable to higher cognitive processes, such as motivation, strategy development and implementation, and voluntary direction and regulation of attention.

Electrophysiological evidence of developmental changes in the duration of auditory sensory memory

In behavioral studies, children's memory for tonal frequency has been found to persist for less time than adults' (T. A. Keller & N. Cowan, 1994). The present study was done to evaluate the argument that this effect is due to changes in auditory sensory memory and not to attentional mechanisms. This question was investigated using mismatch negativity (MMN), an auditory event-related potential considered to be insensitive to attention. Participants were 6-7-, 8-10-, and 11-12-year-old children and adults. They were presented with trains of stimuli, beginning with either a standard (1000 Hz) or a deviant (1200 Hz) tone with trains separated by either 1 s or 8 s. All 4 groups exhibited MMNs after delays of 1 s, but only the adults and oldest children exhibited MMNs after 8 s, indicating that there are maturational changes in the duration of auditory sensory memory.

Electrophysiological evidence of developmental changes in the duration of auditory sensory memory

In behavioral studies, children's memory for tonal frequency has been found to persist for less time than adults' (T. A. Keller & N. Cowan, 1994). The present study was done to evaluate the argument that this effect is due to changes in auditory sensory memory and not to attentional mechanisms. This question was investigated using mismatch negativity (MMN), an auditory event-related potential considered to be insensitive to attention. Participants were 6-7-, 8-10-, and 11-12-year-old children and adults. They were presented with trains of stimuli, beginning with either a standard (1000 Hz) or a deviant (1200 Hz) tone with trains separated by either 1 s or 8 s. All 4 groups exhibited MMNs after delays of 1 s, but only the adults and oldest children exhibited MMNs after 8 s, indicating that there are maturational changes in the duration of auditory sensory memory.

[Kidney transplantation in patients with type I and type II diabetes mellitus]

A total of 618 patients with end-stage renal disease received kidney transplants between 1980 and September 1996. Twenty eight of them were diabetics. Better results were achieved for type 1 diabetic patients than for type 2 (mortality: 5.9% vs 27.3%; functioning graft: 88.2% vs 72.7%). The morbility was also higher in those patients (infections: 81.8% vs 29.4%; vascular complications: 45.5% vs 17.6%). Actuarial patient and graft survival were lower for type 2 than for non diabetic patients. For type 1 diabetics the results are similar to those for non diabetics. Better results can probably be achieved by restricting the selection criteria. The decision to transplant or maintain on dialysis should be made on a case by case basis.

Reactivation of a dormant representation of an auditory stimulus feature

Research with the mismatch negativity component of event-related potentials has uncovered a system that detects change in the acoustic environment on an automatic basis. The system is considered to compare incoming stimuli to representations of the past and to emit an MMN if change is detected. Previous investigations have shown that the relevant memory of the past can become dormant and then be reactivated by a reminder stimulus. It is unclear, however, whether what is reactivated is an holistic representation of stimuli or separate representations of features of stimuli. The present study provides data that supports the latter possibility but leaves open the former one.

Neonatal hip: from anatomy to cost-effective sonography

Therapeutic success in treating congenital dysplasia of the hip is associated with early diagnosis, but the specific neonatal anatomy makes screening difficult. The purpose of this study was to determine whether this specific neonatal anatomy is taken into account by current ultrasound (US) techniques. Anatomic studies were performed on 22 hips, US examinations on 7750 neonatal hips; 2370 untreated hips were reexamined at 1 month by US and at 3 months by X-ray. The transformation of the neonatal cartilaginous acetabulum into an osseous cavity is dependent on harmonious metaphyseal growth and a properly seated femoral head. Defects in the acetabular roof, together with displacement of the femoral head, cause an abnormal anatomical relationship which leads to further deformities. The described sonographic techniques give only partial information on these specific abnormalities. The sonographic monoplanar methods as used in Graf's technique, which relies largely on acetabular development, lead to difficulties in assessing posterior coverage of the femoral head and difficulties in assessing alignment of the metaphyseal weight-bearing surface with the femoral head. Combining Graf's morphological analysis with Novick's dynamic technique enables one to more accurately define the relationship of the femoral head and the acetabulum and increases the reliability and predictive value of the examination, while reducing the number of doubtful cases. This makes screening cost effective.

Feature conjunctions and auditory sensory memory

This study sought to obtain additional evidence that transient auditory memory stores information about conjunctions of features on an automatic basis. The mismatch negativity of event-related potentials was employed because its operations are based on information that is stored in transient auditory memory. The mismatch negativity was found to be elicited by a tone that differed from standard tones in a combination of its perceived location and frequency. The result lends further support to the hypothesis that the system upon which the mismatch negativity relies processes stimuli in an holistic manner.

Storage of feature conjunctions in transient auditory memory

The purpose of this study was to determine whether feature conjunctions are stored in transient auditory memory. The mismatch negativity (MMN), an event-related potential that is elicited by stimuli that differ from a series of preceding stimuli, was used in this endeavour. A tone that differed from the preceding series of stimuli in the conjunction of two of its features, both present in preceding stimuli but in different combinations, was found to elicit the MMN. The data are interpreted to indicate that information about the conjunction of features is stored in the memory.

[Adenocarcinoma of the Vater's ampulla associated with Von Recklinghausen's neurofibromatosis]

Von Recklinghausen's Neurofibromatosis is an autosomal dominant disease of variable manifestations. Association with gastrointestinal and hepatobiliary tumours is well documented, most of them being benign neurofibromas. Other tumours, such as leiomyomas, sarcomas, ganglioneuromas and carcinoids are less frequent. Much rarer is the development of epithelial malignancies and an ontogenic relation is not clear. The authors reports a case of adenocarcinoma of Vater's Ampulla and duodenal neurofibromas, in a patient with Von Recklinghausen's disease, presenting obstructive jaundice.

Anatomic study of the pre- and neonatal hip. Physiopathologic considerations on dysplasia and congenital dislocation of the hip

Therapeutic success in dysplasia and congenital dislocation of the hip depends on an early diagnosis. The physiopathology remains very debatable and several concepts are propounded. For a better physiopathologic understanding, the authors have carried out a study of the morphology and development of 22 pre- and neonatal hips. At first, the acetabulum is cartilaginous and distorted by the moving femoral head; this acetabulum is histologically affected by the femoral pressure. The pathologic hip is characterized by defective posterior bony coverage of the femoral head by the acetabulum. The acetabulum ossifies during the 3 months following birth, forming a cup-like cavity under the pressure of the femoral head. Therefore, neonatal screening tests such as sonography must take place in the first weeks of life.

Lexical processing of visually and auditorily presented nouns and verbs: evidence from reaction time and N400 priming data

We investigated two aspects of lexical organization in normal adults employing behavioral and electrophysiological indices of semantic priming, namely: (1) Is there evidence for differential processing of nouns and verbs? (2) Is there evidence for separate systems for processing of orthographic and phonologic representations of words? Reaction time (RT), N400 amplitude and latency were used to examine the effect of semantic priming on lexical access of auditorily and visually presented nouns and verbs. We found that the temporal patterns of primed RTs and N400 latencies differed for nouns and verbs, indicating a functional difference in processing. However, the absence of topographic differences in N400 between nouns and verbs did not support anatomically distinct representations of these word classes. By contrast, a modality-specific topography at N400, in addition to RT and N400 amplitude differences between auditory and visual conditions, supported the proposed separation of the orthographic and phonologic representations of words. The implications of the findings for general theories of lexical organization are discussed.

[Diabetes mellitus after renal transplant]

Posttransplant Diabetes Mellitus (PTDM) has traditionally been attributed to therapy with steroids, however with the introduction of Cyclosporine (cya) into clinical practice, an increase in the incidence of PTDM was noted. We studied the prevalence of PTDM in Renal transplant recipients and its clinical characteristics.

MATERIALS AND METHODS

355 patients were submitted to a renal transplant between 30/06/80 and 31/12/92. After stabilization of the doses of the immunosuppressive therapy we considered diabetic patients those with fasting glycemic values > or = 140 mg/dl and those with glycemic values between 100-140 mg/dl were given to an oral glucose tolerance test (WHO criteria 1985).

RESULTS

Posttransplant diabetes mellitus occurred in 28 patients (7.9%), 11 females with a mean age of 53.36 +/- 12.75 years and 17 males with a mean age of 51.05 +/- 10.60 years.

DISCUSSION

Due to the great prevalence of alterations in glucose tolerance and their adverse effects on the cardio-vascular system, we think that all renal transplant recipients should be screened.

HIV-2 infection with a long asymptomatic period

We give details of a patient infected with HIV-2 which had what we believe to be the longest asymptomatic period so far reported. The infection was probably acquired though a blood transfusion in Africa 27 years ago. At present the patient remains asymptomatic and her cellular defence mechanisms, evaluated by CD+4 lymphocyte counts and hypersensitivity skin tests, are not severely compromised. HIV-2 has come distinct epidemiological, clinical and biological features which are different from the related HIV-1 and deserve investigation in order for its natural history to be better understood.

The mismatch negativity of event-related potentials as a probe of transient auditory memory: a review

The use of the mismatch negativity as a probe to study the memory upon which it depends is reviewed. Topics about the memory include its duration, its capacity, the kind of information that can be stored in the memory, how the information is stored, whether the memory is accessed in parallel or in series, whether it is hard-wired or can be modified by experience, and its relationship to sensory memory.

[Gastroesophageal reflux in infants: ultrasonographic reading of pHmetry]

BACKGROUND

pH monitoring of the distal esophagus has proved both sensitive and specific in the detection of reflux but has several limitations due to changes over time in esophageal pH and possibility of alkaline reflux. Simultaneous ultrasonographic monitoring can be helpful when interpreting the results.

POPULATION AND METHODS

One thousand infants (80% under 1 year of age) were examined: 500 suffered from vomiting (310 patients), life-threatening events (65 patients) or repeated respiratory diseases (125 patients). Five hundred infants were controls (320 asymptomatic and 180 sibs of patients with SIDS). pHmonitoring and ultrasonography were performed before and after ingestion of milk by vomiting patients and after administration of orange juice in the other symptomatic patients. Control patients were given milk when asymptomatic or orange juice when they belonged to a SIDS sibship.

RESULTS

Ultrasonography permitted to interpret the different phases of the pH curves according to the age of patients, the meals and their nature, the events associated with temporary increase in abdominal pressure, the gravity. pH monitoring was able to recognize 1589 acid reflux but failed to recognize 2091 reflux episodes.

CONCLUSIONS

While pHmonitoring is helpful to demonstrate a relationship between the reflux and such events as apnea, bradycardia, cough, ultrasonography defines a risk based on specificity of reflux and laryngeal or esophageal dysfunction.

Ultrasound of the gastroesophageal junction

In 560 endoscopy examinations performed on infants with severe vomiting, no esophagitis was found without endoscopic herniation of the gastroesophageal junction. The length of the abdominal esophagus therefore appears fundamental in reflux studies. Sonography is one of few techniques able to define the abdominal esophagus in vivo, both in terms of its anatomy and as a functional structure. Accurate assessment of the sonographic canal requires careful measurement under strictly defined clinical conditions. Using such criteria, ultrasound has a better sensitivity than barium studies in detecting small herniations. In addition to the important length measurements of the abdominal esophagus, other morphological and functional data can also be acquired by ultrasound.

Infant apnea and gastroesophageal reflux

The value of a combination of ultrasound studies and barium swallow examination in the analysis of temporal relationships between apnea and reflux is demonstrated. The two techniques allow acute apneic spells induced by gastroesophageal reflux to be documented and underlying specific digestive tract disorders demonstrated. The high incidence of digestive tract disorders in this area has been identified.

Gastro-esophageal reflux: comparative study between sonography and pH monitoring

Sonography appears highly sensitive in characterizing the severity of gastroesophageal reflux, screening the infants at risk of esophagitis. Sonography is also useful in evaluating efficacy of treatment. In our experience reflux is only damaging if constantly repeated and related to severe hiatal dysfunction. Ultrasound (US) is a good alternative for the assessment of hiatal function and gives furthermore indispensable morphological data.

Sonographic diagnosis of lissencephaly

Lissencephaly, a developmental malformation characterized by absence of sulci, may be suggested in dysmorphic or epileptic infants. Real time ultrasonographic findings correlated with typical electroencephalographic abnormalities establish the diagnosis.

Telangiectatic osteosarcoma

Two cases of telangiectatic osteosarcoma are described. The difficulty in differentiating this tumour from aneurysmal bone cyst is emphasized both from the pathological and radiological aspects.

Abnormal 24-hydroxylation of 25-hydroxyvitamin D in the X-linked hypophosphatemic mouse

The effect of extracellular phosphate on the control of 25-hydroxyvitamin D3 24-hydroxylase was studied in normal mice and littermates with X-linked hypophosphatemic rickets (Hyp). 24-Hydroxylase activity and plasma concentrations of 24,25-dihydroxyvitamin D3 were significantly higher in Hyp mice than in normal mice when both groups were fed a normal diet containing 1.22% calcium (Ca) and 0.8% phosphorus (Pi). The differential in 24-hydroxylase activity was exaggerated when serum phosphate was reduced in normal mice by means of a low Pi diet or increased in Hyp mice by means of a high Pi diet. Differences in 24-hydroxylase activity between the two groups of mice were also demonstrated in the presence of varying Pi concentrations in vitro. Thus, in both Hyp and normal mice, 24-hydroxylase activity is influenced in a qualitatively similar manner by serum Pi. Plasma concentrations of 1,25-dihydroxyvitamin D3 were the same in normal and Hyp mice. The data are consistent with the hypothesis that control the renal metabolism of 25-hydroxyvitamin D3 in Hyp mice is reset such tht 24-hydroxylase activity is inappropriate high for the prevailing serum phosphate over a wide range of concentrations.