Lack of prostate cancer radiosensitization by androgen deprivation

PURPOSE

The majority of clinical trials have shown that high-grade prostate cancer patients treated with androgen deprivation (AD) plus radiation (RT) have a survival advantage over those treated with RT alone. One possible mechanism for such a favorable interaction is that AD sensitizes cells to radiation. Animal model studies have provided suggestive evidence that AD sensitizes cells to radiation, but this mechanism is difficult to confirm conclusively in vivo. This question was investigated in LNCaP cells grown in vitro.

METHODS AND MATERIALS

LNCaP cells were cultured in vitro in Dulbecco's modified Eagle's medium (DMEM)-F12 medium, containing 10% fetal bovine serum (complete medium [CM]). AD was achieved by culture in charcoal-stripped serum (SS)-containing medium. Replacement of androgen was done by adding the synthetic androgen R1881 at 1 x 10(-10) M to SS. Apoptosis was measured with a terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. Clonogenic survival was used to determine overall cell death, and the results were corrected for differences in plating efficiency from the various growth conditions.

RESULTS

LNCaP cells were grown in CM, SS, or SS + R1881 medium, and cell counts obtained at 3, 4, and 5 days. Cell number increased exponentially in CM, whereas no increase in cell number was observed in SS medium. Cell counts from growth in SS + R1881 were intermediate between these extremes. Apoptosis was measured to determine if the combination of AD + RT in vitro resulted in supra-additive cell death, as has been previously described in an in vivo model system. The cells were cultured for 3 days before RT and apoptosis quantified 24 h after RT. There was a consistent supra-additive increase in apoptosis in cells exposed to AD + RT (2 or 8 Gy), as compared to either treatment given individually. In contrast, significant radiosensitization by AD was not observed by clonogenic survival even when the conditions of AD were varied. No radiosensitization was observed upon incubation in SS medium for 3, 4, or 5 days before RT, or extending AD after RT for 6 h before plating or 24 h after plating.

CONCLUSION

The results show that in LNCaP prostate tumor cells supra-additive apoptosis does not translate into radiosensitization by clonogenic survival. Because clonogenic survival is a measure of overall cell death, either the level of apoptosis is too small a component of overall cell death or the increases in apoptosis occurred in a subpopulation that would have been killed by other mechanisms. Although the findings indicate that AD does not act by sensitizing prostate cancer cells to RT, the additive cell death and growth inhibitory effects of AD + RT are clinically meaningful.

Familial Mediterranean Fever: association of elevated IgD plasma levels with specific MEFV mutations

Familial Mediterranean Fever (FMF) is a recessively inherited disorder, characterized by episodic fever, abdominal and arthritic pain, as well as other forms of inflammation. Some FMF patients present higher IgD serum levels, and it is not yet known whether such an elevation is related to specific genotypes or correlated with a specific phenotype. In order to evaluate the association between known FMF-related mutations and IgD levels in confirmed patients, as well as the correlation between those levels and the presence of specific clinical signs, genotypic analysis and IgD plasma measurements were performed for 148 Lebanese and Jordanian FMF patients. Most common mutational patterns were M694V heterozygotes (19%) and homozygotes (17%), and V726A heterozygotes (18%) and homozygotes (5%), with an additional 11% combining both mutations. Twenty-one patients had higher IgD levels (superior to 100 microg/ml). The risk for higher IgD levels was significantly associated with M694V homozygote status (OR = 6.25) but not with heterozygotic one (OR = 1). Similarly, the risk for higher IgD was also found with V726A homozygotes (OR = 2.2) but not with heterozygotes (OR = 1.05). The use of colchicine was not statistically associated with IgD levels. Clinically, hyper IgD was also found significantly associated with arthritis (OR = 18). Thus, homozygotic status for M694V, and to a lesser extent V726A, is associated with increased risk for higher IgD plasma levels, regardless of colchicine use. Elevated IgD plasma levels are also correlated with the severity of FMF manifestations, and especially with arthritis.

Mechanisms of action of docosahexaenoic acid in the nervous system

This review describes (from both the animal and human literature) the biological consequences of losses in nervous system docosahexaenoate (DHA). It then concentrates on biological mechanisms that may serve to explain changes in brain and retinal function. Brief consideration is given to actions of DHA as a nonesterified fatty acid and as a docosanoid or other bioactive molecule. The role of DHA-phospholipids in regulating G-protein signaling is presented in the context of studies with rhodopsin. It is clear that the visual pigment responds to the degree of unsaturation of the membrane lipids. At the cell biological level, DHA is shown to have a protective role in a cell culture model of apoptosis in relation to its effects in increasing cellular phosphatidylserine (PS); also, the loss of DHA leads to a loss in PS. Thus, through its effects on PS, DHA may play an important role in the regulation of cell signaling and in cell proliferation. Finally, progress has been made recently in nuclear magnetic resonance studies to delineate differences in molecular structure and order in biomembranes due to subtle changes in the degree of phospholipid unsaturation.

Nonprogressive autosomal recessive ataxia maps to chromosome 9q34-9qter in a large consanguineous Lebanese family

Congenital ataxias are a heterogeneous group of predominantly nonprogressive disorders characterized by hypotonia, developmental delay followed by the appearance of ataxia, and often associated with dysarthria, mental retardation, and atrophy of the cerebellum. We performed a genome-wide screen on a large inbred Lebanese family presenting a nonprogressive autosomal recessive congenital cerebellar ataxia associated with short stature (MIM 213200), already described by Mégarbané and colleagues. The disease locus was assigned to a 12.1 cM interval on chromosome 9q34-9qter between D9S67 and D9S312. Differential diagnosis with other hereditary ataxias linked to the same region is discussed.

Physiological compartmental analysis of alpha-linolenic acid metabolism in adult humans

A physiological compartmental model of alpha-linolenic acid metabolism was derived from the plasma concentration-time curves for d5-18:3n-3, d5-20:5n-3, d5-22:5n-3, and d5-22:6n-3 in eight healthy subjects. Subjects received a 1-g oral dose of an isotope tracer of alpha-linolenate (d5-18:3n-3 ethyl ester) while subsisting on a rigorously controlled beef-based diet. By utilizing the Windows Simulation and Analysis Modeling program, kinetic parameters were determined for each subject. Half-lives and mean transit times of the n-3 fatty acids in the plasma were also determined. The model predicted plasma values for the n-3 fatty acids in good accordance with the measured steady state concentrations and also predicted dietary linolenic acid intake for each subject in accordance with values determined by lipid analysis of the diet. Only about 0.2% of the plasma 18:3n-3 was destined for synthesis of 20:5n-3, approximately 63% of the plasma 20:5n-3 was accessible for production of 22:5n-3, and 37% of 22:5n-3 was available for synthesis of 22:6n-3. The inefficiency of the conversion of 18:3n-3 to 20:5n-3 indicates that the biosynthesis of long-chain n-3 PUFA from alpha-linolenic acid is limited in healthy individuals. In contrast, the much greater rate of transfer of mass from the plasma 20:5n-3 compartment to 22:5n-3 suggests that dietary eicosapentaenoic acid may be well utilized in the biosynthesis of 22:6n-3 in humans.

Measuring clinical performance: comparison and validity of telephone survey and administrative data

OBJECTIVE

To compare and validate self-reported telephone survey and administrative data for two Health Plan Employer Data and Information Set (HEDIS) performance measures: mammography and diabetic retinal exams.

DATA SOURCES/STUDY SETTING

A telephone survey was administered to approximately 700 women and 600 persons with diabetes randomly chosen from each of two health maintenance organizations (HMOs).

STUDY DESIGN

Agreement of survey and administrative data was assessed by using kappa coefficients. Validity measures were assessed by comparing survey and administrative data results to a standard: when the two sources agreed, that was accepted as the standard; when they differed, confirmatory information was sought from medical records to establish the standard. When confirmatory information was not available ranges of estimates consistent with the data were constructed by first assuming that all persons for whom no information was available had received the service and alternately that they had not received the service.

PRINCIPAL FINDINGS

The kappas for mammography were .65 at both HMOs; for retinal exam they were .38 and .40. Sensitivity for both data sources was consistently high. However, specificity was lower for survey (range .44 to .66) than administrative data (.99 to 1.00). The positive predictive value was high for mammography using either data source but differed for retinal exam (survey .69 to .78; administrative data .99 to 1.00).

CONCLUSIONS

Administrative and survey data performed consistently in both HMOs. Although administrative data appeared to have greater specificity than survey data the validity and utility of different data sources for performance measurement have only begun to be explored.

[Neonatal hemorrhagic syndromes]

PURPOSE

The purpose of our study was to clarify the frequency of these causes.

PATIENTS AND METHODS

Retrospective study using reports of newborns in the neonatal unit in Sousse (Tunisia) from 1991 to 1996, hospitalized for hemorrhagic syndrome defined by bleeding, exteriorized or not, whatever its importance, severity, causes and the associated clinical and biological disorders. Isolated meningeal hemorrhages, limited cutaneo-mucous hemorrhages (conjunctival hemorrhages, bruises), and genital crises of the newborn, were excluded.

RESULTS

One hundred and fifty-five hemorrhagic syndromes were observed from 7,128 newborn infants (2.17% of hospitalization). Sex ratio was 1.42. Prematurity rate was 35.7%. The Apgar score was < 7 at one minute in 40.7% of cases. Disorders associated with hemorrhagic syndromes were observed in 118 newborn infants (76.1%) with a predominance of neonatal infections (35.6%). The etiology of neonatal hemorrhages was specified in 93% of cases: newborn hemorrhagic disease (27.7%), disseminated intravascular coagulation (27.1%), isolated thrombocytopenia (9%), digestive lesions (13.5%), and obstetrical trauma (2.6%).

CONCLUSION

The frequency of the newborns hemorrhagic syndromes underlines the need for its systematic prevention by vitamin K in the antenatal period to the mother and after birth to the newborn.

Alterations in brain function after loss of docosahexaenoate due to dietary restriction of n-3 fatty acids

The concentration of the major polyunsaturated fatty acid (PUFA) in brain, docosahexaenoate, may be markedly reduced by two or more generations of dietary restriction of sources of n-3 fatty acids in the diet. Such a deficiency was induced through the feeding of safflower oil as the principal source of essential fatty acids. The reference point for this diet was an n-3 adequate diet to which alpha-linoleate and docosahexaenoate were added through the addition of a small quantity of flax seed or algael oils, respectively. The loss of brain DHA was associated with poorer performance in spatial tasks and an olfactory-cued reversal learning task. No difference could be observed in the hippocampal gross morphology. This study demonstrates the importance of providing a source of n-3 fatty acids during mammalian growth and development.

Rats with low levels of brain docosahexaenoic acid show impaired performance in olfactory-based and spatial learning tasks

Studies were carried out to determine if decreased levels of central nervous system docosahexaenoic acid (DHA), a result of consuming an n-3-deficient diet, had an effect on learning- and memory-related behaviors in adult male rats. Females were reared on an n-3-deficient or n-3-adequate diet beginning at 21 d of life. Their male pups, the F2 generation, were weaned to the diet of the dam and tested at 9-12 wk of age. An olfactory-based discrimination and Morris water maze task were used to assess performance. Whole brain was collected after the behavioral experiments and central nervous system fatty acid content was analyzed in olfactory bulb total lipid extracts. F2 generation male rats consuming the n-3-deficient diet had an 82% decrease in DHA compared to rats consuming the n-3-adequate diet. The n-3-deficient animals made significantly more total errors in a 7-problem, 2-odor discrimination task compared to the n-3-adequate group. Furthermore, the escape latency in the Morris water maze task was significantly longer for the n-3-deficient rats compared to the n-3-adequate rats. These results indicate that rats with decreased DHA levels in the central nervous system perform poorer in these tasks compared to rats with higher DHA levels and suggest the presence of learning deficits in these animals.

A chronic ethanol-feeding study in rhesus monkeys

This study describes the effect of chronic ethanol-feeding in rhesus monkeys. Animals which were maintained on a diet containing 18:2n-6 and 18:3n-3 as 1.4 and 0.08% of the calories, respectively, and consumed alcohol (mean 2.6 g kg(-1) d(-1)) had decreased amounts of 20:4n-6 and 22:6n-3 in their livers and plasma lipids compared with controls. Alcohol consumption did not appear to effect the absorption of 2H(5)-18:2n-6 and 18:3n-3 esters into the blood following an oral dose. There was an increase in 2H5 enrichment in plasma 20:4n-6 and 22:6n-3, indicating that alcohol may have increased production of these fatty acids. There was a greater concentration of 4-hydroxynonenal in the plasma of alcohol-exposed monkeys compared to controls.

Reversal of docosahexaenoic acid deficiency in the rat brain, retina, liver, and serum

The loss of docosahexaenoic acid (DHA) from the retina or brain has been associated with a loss in nervous-system function in experimental animals, as well as in human infants fed vegetable oil-based formulas. The reversibility of the loss of DHA and the compensation by an increase in the n-6 docosapentaenoic acid (DPAn-6) was studied in young adult rats. Long-Evans rats were subjected to a very low level of n-3 fatty acids through two generations. The F2 generation, n-3-deficient animals at 7 weeks of age were provided a repletion diet containing both alpha-linolenate and DHA. A separate group of F2 generation rats had been maintained on an n-3-adequate diet of the same composition. Tissues from the brain, retina, liver, and serum were collected on weeks 0, 1, 2, 4, and 8 from both groups of animals. The concentrations of DHA, DPAn-6, and other fatty acids were determined and the rate of recovery and length of time needed to complete DHA recovery were determined for each tissue. The DHA level in the brain at 1 and 2 weeks after diet reversal was only partially recovered, rising to approximately 20% and 35%, respectively, of the n-3-adequate group level. Full recovery was not obtained until 8 weeks after initiation of the repletion diet. Although the initial rate of retinal DHA accretion was greater than that of brain DHA, the half-time for DHA recovery was only marginally greater. On the other hand, the levels of DHA in the serum and liver were approximately 90% and 100% replaced, respectively, within 2 weeks of diet reversal. A consideration of the total amounts and time courses of DHA repleted in the nervous system compared with the liver and circulation suggests that transport-related processes may limit the rate of DHA repletion in the retina and brain.-- Moriguchi, T., J. Loewke, M. Garrison, J. N. Catalan, N. Salem, Jr. Reversal of docosahexaenoic acid deficiency in the rat brain, retina, liver, and serum. J. Lipid Res. 2001. 42: 419--427.

Olfactory discrimination deficits in n-3 fatty acid-deficient rats

Docosahexaenoic acid (DHA), a long chain n-3 fatty acid, is present in high concentrations in the central nervous system. Although the role that DHA may play in neural function is not well understood, infants fed formulas containing low levels of n-3 fatty acids have decreased visual acuity and neurodevelopmental test scores. The present experiment assessed whether dietary manipulations that decrease the concentration of DHA in the brain interfered with olfactory-based learning. We fed rats a diet that provided adequate n-3 fatty acids or a diet that was deficient in n-3 fatty acids for two generations. The second generation n-3-deficient group had 81% less brain DHA (82% less in olfactory bulb) compared to the n-3-adequate group and made significantly more errors in a series of olfactory-cued, 2-odor discrimination tasks compared to the adequate group. These results suggest that lower levels of central nervous system DHA lead to poorer performance in a series of simple odor discrimination tasks.

Familial Mediterranean fever in Lebanon: mutation spectrum, evidence for cases in Maronites, Greek orthodoxes, Greek catholics, Syriacs and Chiites and for an association between amyloidosis and M694V and M694I mutations

Seventy-nine unrelated Lebanese patients were tested for 15 mutations in the MEFV gene: A761H, A744S, V726A, K695R, M694V, M694I, M694del, M6801 (G --> C), M680I (G --> A) in exon 10, F479L in exon 5, P369S in exon 3, T267I, E167D and E148Q in exon 2, using PCR digestion, ARMS, DGGE and/or sequencing. Mutations were detected in patients belonging to all communities, most interestingly the Maronite, Greek orthodox, Greek catholic, Syriac and Chiite communities. The most frequent mutations are M694V and V726A (27% and 20% of the total alleles respectively). M694I, E148Q and M680I mutations account respectively for 9%, 8% and 5%. Each of the K695R, E167D and F479L mutations was observed once and all the remaining mutations were not encountered. Of the alleles 33% do not carry any of the studied mutations. The mutation spectra, clinical features and severity of the disease differed among the Lebanese communities. The genotype-phenotype analysis showed a significant association (P < 0.001) between amyloidosis and the presence of mutations at codon 694 in exon 10 (both M694V and M694I). None of the patients carrying other mutations developed amyloidosis.

Nutritional deprivation of alpha-linolenic acid decreases but does not abolish turnover and availability of unacylated docosahexaenoic acid and docosahexaenoyl-CoA in rat brain

We applied our in vivo fatty acid method to examine concentrations, incorporation, and turnover rates of docosahexaenoic acid (22:6 n-3) in brains of rats subject to a dietary deficiency of alpha-linolenic acid (18:3 n-3) for three generations. Adult deficient and adequate rats of the F3 generation were infused intravenously with [4, 5-(3)H]docosahexaenoic acid over 5 min, after which brain uptake and distribution of tracer were measured. Before infusion, the plasma 22:6 n-3 level was 0.2 nmol ml(-1) in 18:3 n-3-deficient compared with 10.6 nmol ml(-1) in control rats. Brain unesterified 22:6 n-3 was not detectable, whereas docosahexaenoyl-CoA content was reduced by 95%, and 22:6 n-3 content in different phospholipid classes was reduced by 83-88% in deficient rats. Neither plasma or brain arachidonic acid (20:4 n-6) level was significantly changed with diet. Docosapentaenoic acid (22:5 n-6) reciprocally replaced 22:6 n-3 in brain phospholipids. Calculations using operational equations from our model indicated that 22:6 n-3 incorporation from plasma into brain was reduced 40-fold by 18:3 n-3 deficiency. Recycling of 22:6 n-3 due to deacylation-reacylation within phospholipids was reduced by 30-70% with the deficient diet, but animals nevertheless continued to produce 22:6 n-3 and docosahexaenoyl-CoA for brain function. We propose that functional brain effects of n-3 deficiency reflect altered ratios of n-6 to n-3 fatty acids.

Behavioral deficits associated with dietary induction of decreased brain docosahexaenoic acid concentration

Docosahexaenoic acid (DHA), an n-3 fatty acid, is rapidly deposited during the period of rapid brain development. The influence of n-3 fatty acid deficiency on learning performance in adult rats over two generations was investigated. Rats were fed either an n-3 fatty acid-adequate (n-3 Adq) or -deficient (n-3 Def) diet for three generations (F1-F3). Levels of total brain n-3 fatty acids were reduced in the n-3 Def group by 83 and 87% in the F2 and F3 generations, respectively. In the Morris water maze, the n-3 Def group showed a longer escape latency and delayed acquisition of this task compared with the n-3 Adq group in both generations. The acquisition and memory levels of the n-3 Def group in the F3 generation seemed to be lower than that of the F2 generation. The 22:5n-6/22:6n-3 ratio in the frontal cortex and dams' milk was markedly increased in the n-3 Def group, and this ratio was significantly higher in the F3 generation compared with the F2 generation. These results suggest that learning and cognitive behavior are related to brain DHA status, which, in turn, is related to the levels of the milk/dietary n-3 fatty acids.

[Maternal and perinatal morbidity and mortality associated with hellp syndrome]

OBJECTIVES

Our purpose was to describe the effects of serious obstetric complications on maternal and perinatal outcome in pregnancies complicated by Hellp syndrome.

STUDY DESIGN

Retrospective study.

PATIENTS

Sixteen patients managed from January 1994 through December 1998 in whom pregnancy was complicated by Hellp Syndrome.

RESULTS

The incidence of Hellp syndrome among women with severe preeclampsia and/or eclampsia (164 cases) was 9.7%. Fourteen cases occurred before and two after delivery. In nine cases, Hellp occurred before 32 weeks of gestation and later in two other cases. Mean gestational age at delivery was 32.4 weeks. Serious maternal morbidity included acute renal failure (five cases), disseminated intravascular coagulation (two cases), pulmonary oedema (one case), severe ascites (five cases), pleural effusion (three cases), adult respiratory distress syndrome (one case). Abruptio placenta, acute renal failure and disseminated intravascular coagulation were always associated. Ten patients required transfusions with blood products. Caesarean delivery was performed in 15 cases. General anaesthesia was used in all patients. There was one maternal death from multiple organ failure. Perinatal outcome was poor. Six perinatal deaths were related to abruptio placenta, intrauterine asphyxia and extreme prematurity.

CONCLUSION

The high maternal and perinatal mortality and morbidity reported with the presence of Hellp syndrome requires maternal-fetal follow-up in a tertiary centre where intensive maternal and neonatal care are available.

Prostate cancer radiosensitization in vivo with adenovirus-mediated p53 gene therapy

An adenovirus 5 vector containing wild-type p53 cDNA (Ad5-p53) and a cytomegalovirus promoter was used to generate p53 transgene expression. Control vector (Ad5-pA) contained the poly-adenosine sequence. PC3 cells (2 x 10(6)) were injected s.c. into the legs of nude mice. Treatment with Ad5-p53 was initiated at a tumor volume of 200 mm3. Three intratumoral injections (days 1, 4, and 7) were given with 3 x 10(8) plaque-forming units, followed by 5 Gy pelvic irradiation (day 8) in one fraction using a cobalt-60 source. Tumor volume measurements were obtained every 2 days. LNCaP cells (2 x 10(6)) were injected orthotopically into the prostates of nude mice, and tumor weight was approximated using serum prostate-specific antigen (PSA) obtained from weekly tail vein bleedings. The target PSA for the start of the studies was 5 ng/ml. The intraprostatic injections of Ad5-p53 were done twice (days 1 and 2) and followed by 5 Gy pelvic irradiation on day 3. The PC3 tumor volume growth curves were log transformed and fitted using linear regression. The times (in days) for the tumors to reach 500 mm3 were calculated as 10.7 +/- 0.7 (+/- SE) for the saline control (no virus), 9.8 +/- 2.1 for Ad5-pA, 15.6 +/- 1.6 for Ad5-p53, 14.6 +/- 1.5 radiation therapy (RT; 5 Gy), 14.6 +/- 1.5 for Ad5-pA plus RT, and 31.4 +/- 5.3 for Ad5-p53 plus RT. The Ad5-p53 plus RT times were significantly different from the other groups. An enhancement factor of 3.4 was calculated, indicating supra-additivity. LNCaP tumor growth was determined via weekly serum PSA measurements. Treatment failure was determined using two PSA-based methods; a serum PSA of > 1.5 ng/ml or two rises in PSA during 6 weeks posttreatment. The results were similar using either end point. Treatment with Ad5-p53 plus 5 Gy resulted in significantly fewer PSA failures (<30%), as compared with Ad5-p53 alone (64-73%) and the other controls (approximately 80-100%) These results are also consistent with a supra-additive inhibition of tumor growth. Tumor growth in vivo was inhibited supra-additively when p53null and p53wildtype prostate tumors were treated with Ad5-p53 and 5 Gy radiation.

X-linked transposition of the great arteries and incomplete penetrance among males with a nonsense mutation in ZIC3

We report on a Lebanese family in which two maternal cousins suffered and died very early in life from cardiac malformations. Both presented with a transposition of the great arteries associated with one or several other cardiac defects. Various minor midline defects were also observed, but there were no situs abnormalities other than a persistent left superior vena cava in one. A maternal uncle of these two babies was born cyanotic and died on the third post-natal day. Analysis of the ZIC3 gene, revealed the presence of a mutation in the second exon leading to a truncation of the protein. Surprisingly, another maternal uncle of the two affected cousins also had the mutation but was not clinically affected. To our knowledge, this is the first instance of incomplete penetrance in a male for a mutation in a chromosome X gene.

A defect in harmonin, a PDZ domain-containing protein expressed in the inner ear sensory hair cells, underlies Usher syndrome type 1C

Usher syndrome type 1 (USH1) is an autosomal recessive sensory defect involving congenital profound sensorineural deafness, vestibular dysfunction and blindness (due to progressive retinitis pigmentosa)1. Six different USH1 loci have been reported. So far, only MYO7A (USH1B), encoding myosin VIIA, has been identified as a gene whose mutation causes the disease. Here, we report a gene underlying USH1C (MIM 276904), a USH1 subtype described in a population of Acadian descendants from Louisiana and in a Lebanese family. We identified this gene (USH1C), encoding a PDZ-domain-containing protein, harmonin, in a subtracted mouse cDNA library derived from inner ear sensory areas. In patients we found a splice-site mutation, a frameshift mutation and the expansion of an intronic variable number of tandem repeat (VNTR). We showed that, in the mouse inner ear, only the sensory hair cells express harmonin. The inner ear Ush1c transcripts predicted several harmonin isoforms, some containing an additional coiled-coil domain and a proline- and serine-rich region. As several of these transcripts were absent from the eye, we propose that USH1C also underlies the DFNB18 form of isolated deafness.

Long-chain polyunsaturated fatty acids

Long-chain polyunsaturated fatty acids (LC-PUFA) are essential for normal development. Fetal accretion of LC-PUFA occurs during the last trimester of gestation; therefore, premature infants are born with minimal LC-PUFA reserves. Recent studies indicate that the newborn can synthesize LC-PUFA from essential fatty acid precursors; however, the extent of de novo synthesis remains to be established. Postnatally, human milk provides LC-PUFA to the newborn. Maternal LC-PUFA reserves depend upon diet and can be improved by supplementation of docosahexaenoic acid and arachidonic acid during pregnancy and lactation. This in turn affects fetal LC-PUFA accretion and postnatal provision through mother's milk. Supplementation of formula-fed preterm or full-term infants with docosahexaenoic acid and arachidonic acid leads to plasma and red blood cell LC-PUFA levels similar to those of breast-fed infants. The higher blood and presumably tissue levels of LC-PUFA following supplementation lead, however, to only temporary functional benefits.