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N P Laborde

Publications and source records attributed to N P Laborde.

11 recordsLinked to original sources
PubMed1988

The source of urinary epidermal growth factor in humans.

To clarify the source of human urine EGF, we studied EGF renal clearance in 20 healthy, young adult subjects. Immunoreactive EGF was measured hourly in EDTA plasma, heparin plasma, serum and urine of 12 males and 8 females during a 3 h study period. Plasma and urine creatinine and creatinine clearance were measured and calculated hourly. Mean (and SEM) creatinine clearance was similar in males and females (118 +/- 12 vs 105 +/- 6 ml/min). EGF was not detectable in plasma, whereas relatively high levels were measured in serum (2.5 +/- 0.25 vs 1.5 +/- 0.18 ng/ml in males and females respectively p less than 0.05). Urine EGF excretion averaged 1641 +/- 233 ng/h in males and 1507 +/- 191 ng/h in females (p greater than 0.05). A significant correlation was observed between urine creatinine and urine EGF concentrations in both male (r = 0.98, p less than 0.01) and female (r = 0.94, p less than 0.01) subjects. EGF immunoreactivity in urine and serum eluted from G-75 sephadex columns similarly to recombinant 6000 Mr hEGF. Urine excretion of EGF approximated 1.5 micrograms/h or 25 ng/mg creatine. The high concentrations of EGF found in urine in the face of non-detectable levels of EGF in plasma favor the hypothesis that EGF in urine is derived from kidney synthesis and secretion. The significant positive correlation between urine creatinine and urine EGF suggests a functional correlation between glomerular filtration and the process of tubular EGF excretion.

Adult↗
PubMed1988

Ontogenesis of epidermal growth factor in liver of BALB mice.

To characterize the ontogenesis of hepatic epidermal growth factor (EGF) metabolism in normal BALB mice, we measured serum and liver concentrations of EGF and liver concentrations of pre-pro EGF mRNA. Female and male animals were studied at 1, 2, 5, 7, and 10 wk of life. After death, body weight and length were measured, and serum and liver tissues were collected for EGF determinations. Immunoreactive serum EGF (means +/- SE) increased at 7 and 10 wk and was significantly higher (P less than 0.05) in males (465 +/- 58 and 683 +/- 120 pg/ml) than females (188 +/- 52 and 295 +/- 64 pg/ml). Liver EGF concentrations were low at 1, 2, and 5 wk, significantly increasing (P less than 0.01) at 10 wk to 179 +/- 36 vs. 268 +/- 49 pg/mg protein for females and males, respectively (female and male values were significantly different, P less than 0.01). Pre-pro EGF mRNA was examined at 1, 2, 3, 5, 7 and 10 wk. EGF message increased in liver to highest values at 10 wk in both males and females. There was a high correlation between serum and liver EGF concentrations during the first 10 wk (r = 0.97 and 0.85 for males and females, respectively) and a twofold increase in liver EGF mRNA between 3 and 10 wk of postnatal life. These results suggest that liver may be an important source of circulating EGF in developing BALB mice.

Animals↗
PubMed1987

Nerve growth factor immunoreactivity in mouse kidney: an immunoelectron microscopic study.

We have recently reported the immunolocalization of nerve growth factor (NGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of NGF by the preembedding immunoperoxidase method for electron microscopy. NGF immunoreactivity was present in the connecting tubule cells of the distal nephron. These cells showed immunostaining associated with the Golgi complex, vesicles, rough endoplasmic reticulum (RER), and polyribosomes. The intercalated cells, in contrast, lacked immunoreactivity.

Animals↗
PubMed1986

Immunocytochemical localization of nerve growth factor in mouse kidney.

The presence of NGF in mouse kidney was investigated using immunocytochemical methods. Female and male adult Swiss-Webster mouse kidneys were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative. The kidneys were frozen, and serial sections were prepared. Rabbit NGF antiserum was used for the primary incubation, and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. NGF immunoreactivity was localized in the apical and perinuclear cytoplasm of cells lining the late distal nephron, in a portion that corresponds to the connecting tubule. This portion of the nephron has been consistently observed in close anatomical relationship with arterioles, which are known to be richly innervated. Some cells of the connecting tubule, corresponding to intercalated cells, lacked NGF immunoreactivity.

Animals↗
PubMed1986

Immunocytochemical localization of epidermal growth factor in mouse kidney.

Epidermal growth factor (EGF) was originally isolated from mouse submandibular glands (SMG). However, SMG removal failed to lower circulating EGF, and large amounts of EGF have been found in mouse urine. In addition, the presence of pre-pro-EGF mRNA in mouse kidney has recently been reported by others. Kidneys may therefore represent an alternate source of EGF. In the present study, we investigated the immunocytochemical localization of EGF in mouse kidney. Male and female adult Swiss Webster mice were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative, the kidneys were frozen, and serial sections were obtained. Rabbit EGF antiserum was used for the primary incubation and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. EGF was immunolocalized in the apical portion of the cells lining the thick ascending limb of Henle (TALH) and the distal convoluted tubule (DCT). The macula densa, in contrast, lacked EGF immunoreactivity. No sex differences were observed in the distribution pattern or intensity of immunostaining. Infusion of EGF into sheep renal artery has been reported to induce changes in urine flow and ionic composition. Immunolocalization of EGF in the TALH and DCT documented here supports a regulatory role for EGF in the function of the mouse distal nephron.

Animals↗
PubMed1984

Effects of short-term hyperprolactinemia on the endocrine reproductive system in male rabbits.

We have systematically studied the effects of short-term hyperprolactinemia on reproductive function in male rabbits. Purified ovine prolactin (PRL) was administered intravenously, as bolus injections or by constant infusion, to unanesthetized animals bearing two chronically implanted Silastic catheters; blood samples were obtained via the second catheter. Short-term hyperprolactinemia did not modify serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations in either castrated or intact rabbits. However, in spite of no changes in LH and FSH, short-term PRL administration lowered the serum testosterone (T) in intact animals. Furthermore, while PRL had no effect on the LH and FSH response to gonadotropin-releasing hormone, it did inhibit the testicular secretion of T in response to the increased endogenous LH. PRL also inhibited human chorionic gonadotropin-stimulated T secretion by the testes. All of these studies indicate that PRL interferes with the testicular response to LH. The fact that LH and FSH did not rise in response to the lowered T in intact animals suggested that PRL also altered the steroid feedback control of LH and FSH secretion. To assess this, PRL or saline was repeatedly injected after castration. PRL prevented the postcastration rise in LH and FSH. These studies indicate that PRL acts at at least two sites in the reproductive system in rabbits: (1) directly at a gonadal level by interfering with gonadotropin action and (2) at a hypothalamic-pituitary central level by preventing the expected rise in gonadotropins in response to low gonadal steroids.

Animals↗
PubMed1984

Autoregulatory control of thyrotropin in rabbits.

Studies were designed to determine whether an autoregulation system exists for TSH in the rabbit. For this purpose, a species-specific RIA for rabbit TSH that does not cross-react with human (h) TSH was developed. Hypothyroid animals were studied at varying time periods up to 3 months after either surgical thyroidectomy or propylthiouracil (PTU) treatment. Highly purified hTSH was injected iv at doses of 0 (saline control), 0.1, 0.3, 1,3, and 10 micrograms into unanesthetized rabbits bearing chronically implanted Silastic catheters. Blood samples were obtained at -30, 0, 10, 20, 30, 60, 120, 180, 240, and 300 min and 24 h. Doses between 0.3 and 10 micrograms hTSH produced a prompt fall (10 min) in rabbit TSH in hypothyroid rabbits studied 8-21 days after thyroidectomy. The minimum dose of hTSH that significantly suppressed rabbit TSH was 0.3 micrograms. This dose produced a peak value of hTSH in rabbit serum of 1.3 +/- 0.1 (+/- SEM) ng/ml 10 min after injection, which translates into a bioassay potency of 2.0 microU/ml (close to the physiological level in humans). A dose-response relationship existed between the hTSH dose injected and the duration and magnitude of suppression of rabbit TSH. This response to TSH was specific; 10 micrograms hTSH produced no change in endogenous rabbit serum LH and, conversely, 10 IU hLH produced no change in rabbit serum TSH. In contrast to these striking effects in acute hypothyroid animals, hTSH produced no detectable suppression of rabbit TSH in animals that were hypothyroid for 2-3 months. The sensitivity of the autoregulatory system to the suppressive effects of exogenous hTSH decreased with increasing duration of hypothyroidism; a time-response relationship existed. We conclude that: 1) a sensitive and specific autoregulatory control system for TSH exists in the rabbit; and 2) as the duration of hypothyroidism increases, the sensitivity of the autoregulatory system to the suppressive effects of endogenous TSH changes.

Animals↗
PubMed1983

A simple and sensitive solid-phase radioimmunoassay for the assay of human TSH antibody. Use in screening hybridoma cell lines.

A simple and sensitive radioimmunoassay procedure is described for the screening and detection of specific antibodies in hybridoma cell lines. The specific procedure was developed to screen for antibodies against human thyrotropin (hTSH), but the procedure is applicable to screening for any desired antibodies. The immunoglobulin G(IgG) fraction of goat anti-mouse IgG is used to coat wells of microtiter plates. Anti-hTSH antibodies are measured by incubating antiserum dilutions in the coated wells and detecting the bound IgG with radioiodinated hTSH. Unlabeled hTSH may also be detected by its ability to inhibit binding of 125I-hTSH to the coated wells. This assay technique meets the demands of simplicity, sensitivity, reproducibility, and rapidity as a screening assay of hybridoma cell lines capable of secreting anti h-TSH.

Animals↗
PubMed1981

Short loop feedback system for the control of follicle-stimulating hormone in the rabbit.

Studies were designed to assess whether a short loop feedback control for FSH existed in the rabbit. Castrated adult female animals bearing chronically implanted Silastic catheters to permit frequent blood sampling were studied without anesthesia. Ovine FSH was administered as an iv bolus in doses ranging between 0.1-500 micrograms. Endogenous rabbit FSH was quantified using a RIA that did not cross-react with ovine FSH. Blood samples were obtained before and 5, 10, 15, 30, 60, 120, 180, 240, and 300 min after the injection. Each animal was tested at two or more dose levels on different days. Ovine FSH produced suppression of rabbit FSH secretion within 5 min after injection. The minimum effective dose was 1 microgram; maximal suppression occurred with 50-100 micrograms ovine FSH. This short loop feedback control system was specific for FSH; ovine FSH, even at high doses, failed to suppress endogenous rabbit LH. This is the first direct demonstration of a negative short loop feedback control for FSH and the first entirely specific control for the FSH system to be described.

Animals↗
PubMedDate not supplied

[Bovine milk progesterone concentration as a method of early diagnosis of pregnancy (author's transl)].

With the purpose of obtaining an early indicator of pregnancy in bovines, excretion levels of milk progesterone were determined by a simple radioimmunological method. In the pregnant group, progesterone concentration was significantly (p less than 0,001) greater than in non-pregnant ones. In some cases (20-25%) there was no difference in values, resulting a method efficiency of 75-80%. Milk must be processed a few hours after collection since a decrease in progesterone values is observed within a few days. Easy obtention of this biological matherial, without special technical requirements as well as the simple dosification method make this test a practical index for establishing early diagnosis of pregnancy in bovines.

Animals↗