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Biomedical subjects

D A Price

Publications and source records attributed to D A Price.

At least 181 records · Page 10Linked to original sources
PubMed1990

Seven FMRFamide-related and two SCP-related cardioactive peptides from Helix.

Pulmonate snails have a more complex array of cardioexcitatory peptides than other molluscs, and Helix has a more complex array than most other pulmonates. Since a full characterisation of the cardioexcitatory peptides is necessary for an understanding of physiology, we sought to identify the members of two families of such peptides - the small cardioactive peptides (SCPs) and the FMRFamide-related peptides (FaRPs) - from Helix aspersa. We characterised the peaks of immunoreactivity from HPLC both by their elution times and by their molecular weights as determined by fast atom bombardment mass spectrometry (FABms). These two criteria, used in parallel, facilitated our identification of several known peptides: MNYLAFPRMamide, identical to SCPB of Aplysia; two tetrapeptide FaRPs, FRMRamide and FLRFamide; and three hepatapeptide FaRPs, NDPFLRFamide, SDPFLRFamide and pQDPFLRFamide. Of these peptides, only FMRFamide and pQDPFLRFamide have previously been reported from Helix. We also discovered an additional SCP and two novel FaRPs and sequenced them. The SCP is Ser-Gly-Tyr-Leu-Ala-Phe-Pro-Arg-Met-amide (SGYLAFPRMamide), and the heptapeptide FaRPs are Asn-Asp-Pro-Tyr-Leu-Arg-Phe-amide (NDPYLRFamide) and Ser-Glu-Pro-Tyr-Leu-Arg-Phe-amide (SEPYLRFamide). When these nine peptides were tested on isolated Helix ventricles, the SCPs were the most potent cardioexcitors, the heptapeptide FaRPs were next, and the tetrapeptides had the least activity.

Amino Acid Sequence↗
PubMed1989

Isolation, characterization, and amino acid sequence of a polypeptide neurotoxin occurring in the sea anemone Stichodactyla helianthus.

An aqueous exudate collected from frozen and thawed bodies of a Caribbean sea anemone, Stichodactyla (formerly Stoichactis) helianthus, contained a polypeptide neurotoxin (Sh I) selectively toxic to crustaceans. The polypeptide was purified by G-50 Sephadex, phosphocellulose, and sulfopropyl-Sephadex chromatography and shown to have a molecular size of 5200 daltons and a pI of 8.3. The amino acid sequence determined by automatic Edman degradations of whole RCM Sh I and of its clostripain, staphylococcal protease, and cyanogen bromide digest peptides is A1ACKC5DDEGP10DIRTA15PLTGT20VDLGS25CNAGW30EKCAS35YYTII40ADCCR45KKK . Only 33% of this sequence is identical with the sequence of Anemonia sulcata toxin II, a sea anemone toxin isolated from the taxonomic family Actiniidae. The six half-cystines are located in equivalent positions to those of the actiniid toxins and account for nearly half of the residues common to all of the toxins. However, 69% of the Sh I sequence is identical with that of toxin II from Heteractis paumotensis, another sea anemone belonging to the family Stichodactylidae. Stichodactylid toxins lack the initial N-terminal residue of actiniid toxins and possess three consecutive acidic residues at positions 6-8, a single tryptophan at position 30, and four consecutive basic residues at positions 45-48 (C-terminus). A rabbit IgG prepared by Sh I immunization bound Sh I with a K0.5 of 4.7 nM but failed to bind homologous actiniid (Anemonia sulcata II, Condylactis gigantea III) or bolocerid (Bolocera tuedae II) polypeptide neurotoxins.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

Pulsed field gel electrophoresis identifies a high degree of variability in the number of tandem 21-hydroxylase and complement C4 gene repeats in 21-hydroxylase deficiency haplotypes.

The human steroid 21-hydroxylase gene, CYP21B, and its closely homologous pseudogene, CYP21A, are each normally located centromeric to a complement C4 gene C4B and C4A respectively, in an organization suggesting tandem duplication of a CYP21 + C4 unit. Such an organization has been considered to facilitate gene deletion and addition events by unequal crossover between the tandem repeats. However, the large size (approximately 30 kb) of the individual CYP21 + C4 repeat units together with the difficulty in identifying reliable CYP21A- and CYP21B-specific markers has prevented direct monitoring of gene organization on individual haplotypes by conventional Southern analyses. In the present investigation we have sought to clarify the CYP21 and C4 gene organization in members of 32 British 21-hydroxylase deficiency families by employing additional experimental approaches, notably a long-range restriction mapping approach, which permits assessment through a VNTR type of analysis, of the number of CYP21 and C4 units on individual haplotypes. Our results show that there is a very high frequency (33%) of 21-hydroxylase deficiency haplotypes where functional CYP21B gene sequence has been removed as a consequence of CYP21 + C4 gene deletion while several haplotypes show evidence of gene addition. In each case that we have investigated the gene deletion and gene addition haplotypes differ in length from conventional haplotypes by integral multiples of approximately 30 kb, which strongly supports the involvement of unequal crossover mechanisms. Additionally, the comparatively frequent occurrence of CYP21 fusion genes which contain both CYP21A- and CYP21B-associated markers is suggested by the combined data from Southern analyses, long-range restriction mapping and characterization of selected regions of CYP21 genes which have been amplified in vitro.

Adrenal Hyperplasia, Congenital↗
PubMed1989

Ovarian function following chemotherapy for childhood brain tumours.

Pubertal development, basal gonadotrophin, and oestradiol levels were assessed in 21 girls who had received neuroaxis irradiation for a brain tumour followed by adjuvant chemotherapy with carmustine (BCNU) or lomustine (CCNU) and procarbazine. Thirteen received chemotherapy before the age of 11 years. Ten remained prepubertal at their last assessment, nine of whom showed biochemical evidence of primary ovarian failure. The remaining three were pubertal or adult, and although basal follicle-stimulating hormone (FSH) and luteinising hormone (LH) levels were normal, all had shown abnormalities of gonadotrophin secretion previously. Eight girls received chemotherapy after 11 years of age. Only three girls exhibited an elevated basal FSH level or exaggerated FSH response to GnRH. Elevated basal FSH values had been noted previously in two of the other five girls. All girls entered or progressed through puberty spontaneously. Seven experienced menarche at an appropriate age. However in four, gonadotrophin levels, which had been elevated, were now within the normal range. In two, menses had continued throughout with normal midfollicular oestradiol levels, whilst the other two developed secondary amenorrhoea associated with radiation-induced gonadotrophin deficiency. The majority of girls showed evidence of primary ovarian dysfunction. This did not prejudice pubertal development or the timing of menarche. Ovarian function may return to normal in the years after treatment, indicating a potential for fertility.

Adolescent↗
PubMed1989

Gonadal dysfunction due to cis-platinum.

Gonadal function was studied in 15 patients 12 pubertal or postpubertal, and three prepubertal, who had been treated during childhood for nonmetastatic osteosarcoma of the long bones by chemotherapy regimens that included cis-platinum and adriamycin. Of seven postpubertal female patients assessed (mean age at diagnosis 16.5 years), three were amenorrhoeic and showed evidence of ovarian damage with raised gonadotrophin levels and a low serum oestradiol concentration. One patient who had regular periods had a raised luteal-phase follicle-stimulating hormone (FSH) concentration suggestive of gonadal dysfunction. Severe oligospermia or reduced testicular volumes in the presence of raised gonadotrophin levels were observed in three of the five pubertal males (mean age at diagnosis 13.25 years). A reliable assessment of gonadal function was not possible in three male patients who remained prepubertal at the time of study. The median total dose of cis-platinum received by those patients with gonadal damage (median dose, 490 mg) was significantly higher than in those patients with normal gonadal function (median dose, 300 mg) (P = 0.01). In the boys the damage to the testes was primarily directed at the germinal epithelium. Leydig cell function was intact and the males progressed spontaneously through puberty. In the girls, unlike the boys, there was evidence of reversibility of gonadal damage with time. This is the first study to show gonadal dysfunction due to cis-platinum and adriamycin therapy in childhood.

Adolescent↗
PubMed1989

The identification, localization, and pharmacology of FMRFamide-related peptides and SCPB in the penis and crop of the terrestrial slug, Limax maximus.

1. The molluscan neuropeptides FMRFamide, pQDPFLRFamide, and SCPB were tested on the isolated crop and penis of the terrestraial slug, Limax maximus. FMRFamide and pQDPFLRFamide stimulated the penis and inhibited contractions of the crop. In contrast, SCPB either stimulated or relaxed the penis and increased the tone of the crop. 2. Fibers and varicosities containing immunoreactive (ir-) FMRFamide and ir-SCPB were located in the penis and crop. 3. Extracts of penes, crops, ganglia, and whole animals all contained FMRFamide, FLRFamide, SDPFLRFamide, NDPFLRFamide, and pQDPFLRFamide. 4. These results suggest that the FMRFamide-related peptides and SCPB are involved in the regulation of the reproductive and digestive activities of Limax.

Animals↗
PubMed1989

21-hydroxylase deficiency families with HLA identical affected and unaffected sibs.

During our investigations of polymorphisms at, and in the immediate chromosomal vicinity of, the 21-hydroxylase locus in families with 21-hydroxylase deficiency, three families were found to show marked discordance in clinical features of HLA identical subjects. In one family, there is discordance between a boy with the simple virilising form of 21-hydroxylase deficiency and his two younger sisters, who are both HLA identical to their brother, but who have additional salt wasting features. In the other two families, one subject is severely affected and has very high 17-hydroxyprogesterone levels, but has an HLA identical sib who is asymptomatic and shows only slightly raised 17-hydroxyprogesterone levels. In all cases, HLA identity, as indicated by protein polymorphism studies (HLA-A, B, DR, C4A, C4B, and Bf typing), has been verified at the gene organisation level using 21-hydroxylase and complement C4 DNA probes. An HLA-Bw47 bearing haplotype in one of the latter families has not been transmitted to the affected child and appears to carry a normal 21-OHB allele and two genes which specify C4A allotypes.

Adrenal Hyperplasia, Congenital↗
PubMed1988

Growth in children treated for acute lymphoblastic leukaemia.

Growth was assessed in 82 children with acute lymphoblastic leukaemia (ALL) who achieved complete continuous first remission following treatment. 34 received prophylactic cranial irradiation at a total dose over 2000 cGy (group I) and 48 at a dose of 1800 cGy (group II). Chemotherapy was given over two or three years and was more intense in group II. Both groups showed a similar significant decrease in height standard deviation score (SDS) over four years (group I -0.31, group II -0.39). 15 children in group I were followed to ten years and continued to show restricted growth with a mean height SDS decrease of -0.84 (range 0 to -1.7). The greatest reduction in yearly decrements in height SDS occurred in the first year after diagnosis. In both groups height SDS increased significantly on completion of chemotherapy. Thus chemotherapy protocols contribute to growth retardation in ALL. In most of these children the mean loss of height over ten years was not sufficiently great to justify long-term growth hormone (GH) therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Growth response to growth hormone therapy following cranial irradiation.

The growth response to growth hormone (GH) therapy has been studied in 12 children who received irradiation to the cranium alone either for brain gliomas, distant from the hypothalamic-pituitary axis, or as prophylaxis against CNS leukaemia. Seven children have completed GH treatment (mean duration 4 years) and five are presently on GH (mean duration 1.2 years). This response has been compared to that seen in 14 children with isolated idiopathic GH deficiency (IGHD), following GH therapy. Before treatment, the cranially irradiated patients (C-PRGHD) had higher standard deviation scores (SDS) for standing height, sitting height and leg length, and less bone age (BA) retardation, but started treatment at a similar age, and with a similar pre-treatment growth velocity and GH peak to standard provocative tests, compared to IGHD patients. GH produced a significant and similar increase in growth velocity (cm/year and SDS for BA) over the first 2 years' treatment in both groups. However C-PRGHD patients entered puberty and thus completed growth earlier than the IGHD group. As a result, cranially-irradiated children showed no change in height SDS with GH therapy, compared to catch-up growth in IGHD. Nevertheless, GH has enabled C-PRGHD patients to maintain their centile position and to achieve a more acceptable final height.

Body Height↗
PubMed1988

Growth response to growth hormone therapy following craniospinal irradiation.

Nineteen (12 male, 7 female) children, who have received craniospinal irradiation for the treatment of a brain tumour distant from the hypothalamic-pituitary axis, resulting in growth hormone (GH) deficiency (CS-PRGHD), have been treated with GH. Eight have completed growth. Comparison has been made with the growth of seven untreated children, whose heights and growth rates at presentation were normal despite GH deficiency secondary to irradiation. GH produced a significant increase in growth velocity over the first 3 years' treatment in CS-PRGHD patients with a mean first year increment of 3 cm/year. Patients, treated to completion of growth, showed a significant increase in leg length standard deviation (SD) score (delta SDS + 0.2) compared to that of the untreated (delta SDS - 0.9) (P less than 0.05). Sitting height SD scores decreased irrespective of GH therapy (by -1.7 for the treated and -2.2 for the untreated). The onset of puberty in the irradiated patients occurred at a mean bone age of 10.7 years in males and 9.9 years in females. This limited the time available for GH therapy. These factors resulted in a decrease in standing height SDS of 0.9 at completion of GH therapy in CS-PRGHD, but a decrease of 1.7 in those not treated with GH. Thus GH therapy failed to induce "catch-up" growth in irradiated patients, but it did prevent further loss of adult stature, with a mean final height SD score of -3.4 in CS-PRGHD patients.

Body Height↗
PubMed1988

Relationships between the FMRFamide-related peptides and other peptide families.

The relationships between peptide families are recognized in terms of structural similarity and immunological and biological activity. Most of the currently known FMRFamide-related peptides (FaRPs) of molluscs were tested in a radioimmunoassay (RIA) and in the two standard bioassays for FMRFamide: the radula protractor muscle of the whelk Busycon contrarium, and the isolated heart of the clam Mercenaria mercenaria. Some peptides were also tested on the heart of the snail Helix aspersa. The responses of the different assays to these peptides were generally similar, but substantial diversity precluded an absolute resolution of relationships, even among molluscan FaRPs. Nevertheless, this set of responses does constitute a standard against which to estimate the relative affinities of putative FaRPs from other animal groups. Many of the non-molluscan FaRPs (e.g., the pancreatic polypeptide-related peptides, gastrin/CCK, and the opioid peptides) are relatively inactive on the molluscan assays, but others (e.g., LPLRFamide, a peptide isolated from chicken brain; the opioid receptor-modulating peptides A18Fa and F8Fa; and gamma 1-MSH) were relatively potent. Several arthropod FaRPs have substantial FMRFamide-like sequence similarity and immunoreactivity, and they may be homologous members of the molluscan peptide family. However, those structural and functional aspects of peptide families that transcend phyletic lines probably reflect basic principles of binding between peptides and membrane proteins rather than homology.

Amino Acid Sequence↗
PubMed1988

Growth and growth hormone responses to oxandrolone in boys with constitutional delay of growth and puberty (CDGP).

Thirteen boys with constitutional delay in growth and/or development aged 7.6 to 16 years received 2.5 mg/day of oxandrolone for 3 months. Their growth response on treatment and in the subsequent 3 months was compared to that of 14 age-matched untreated controls. Growth rates were analysed in groups arbitrarily defined by testicular volume at entry (less than 4 ml prepubertal, greater than 4 ml pubertal). Growth velocities increased on oxandrolone (prepubertal, mean 4.4 to 7.5 cm/year, P = 0.05: pubertal, mean 4.7 to 8 cm/year, P less than 0.05). Over the next 3 months, the pubertal boys grew at 9.3 cm/year, while the prepubertal group decelerated to 6.2 cm/year. Both control groups showed no significant change in velocity over 6 months. GH responses to arginine and GRF, and to sleep in prepubertal boys, were unchanged throughout the study. However, in pubertal boys the mean GH levels ('area under the curve') during sleep at 3 and 6 months, had increased over baseline values, associated with a significant increase at 6 months in basal somatomedin-C (140 to 214 ng/ml, P less than 0.05). Oxandrolone does not alter the GH status of prepubertal boys, and thus probably promotes growth by a direct action at the growth plate. In contrast, the persistent growth acceleration of pubertal boys may be associated with increased GH and somatomedin-C levels: in this group, oxandrolone has proved a useful stimulus to growth.

Adolescent↗