Identification of two epidermal growth factor-sensitive tyrosine phosphorylation sites of phospholipase C-gamma in intact HSC-1 cells

The 145-kDa phospholipase C isozyme, PLC-gamma, is an excellent substrate for the epidermal growth factor (EGF) receptor both in vivo and in vitro. We now demonstrate that EGF treatment of HSC-1 cells, a human squamous cell carcinoma-derived cell line that expresses high levels of the EGF receptor, rapidly induces tyrosine phosphorylation of two-thirds of the total cellular PLC-gamma pool. A two-step immunoaffinity protocol was used for large-scale isolation of phosphorylated PLC-gamma from the cytosol of EGF-treated HSC-1 cells. Phosphorylated PLC-gamma was digested with trypsin, then phosphotyrosine-containing peptides were purified by phosphotyrosine affinity chromatography and reverse-phase high performance liquid chromatography. The two major phosphotyrosine-containing tryptic peptides were sequenced. Comparison of the sequence data with the bovine brain PLC-gamma amino acid sequence indicated that the major, EGF-sensitive tyrosine phosphorylation sites of human PLC-gamma correspond to the bovine brain PLC-gamma tyrosine residues 771 and 1254. The former residue is adjacent to regions of PLC-gamma that contain high homology to the non-catalytic, amino-terminal region of the src tyrosine kinase. The latter residue lies near the carboxyl terminus of the PLC-gamma molecule. The accompanying manuscript (Kim J.W., Sim, S.S., Kim, U-H., Nishibe, S., Wahl, M. I., Carpenter, G., and Rhe, S. G. (1990) J. Biol. Chem. 265, 3940-3943) identifies these same 2 residues plus 2 additional tyrosine phosphorylation sites through large-scale in vitro phosphorylation of purified bovine brain PLC-gamma by the EGF receptor.

Regulation of insulin-like growth factor-I ribonucleic acid expression, polypeptide secretion, and binding protein activity by growth hormone in porcine preadipocyte cultures

Insulin-like growth factor-I (IGF-I) is a mitogenic polypeptide postulated to mediate the effect of GH on adipose tissue development. To determine if the effect of GH could be mediated by the local production of IGF-I, we have characterized IGF-I RNA expression, polypeptide secretion, and binding protein activity in primary preadipocyte cultures derived from porcine adipose tissues. GH acutely regulated the abundance of multiple IGF-I RNA transcripts and resulted in a 2-fold increase in secreted immunoreactive IGF-I (iIGF-I) polypeptide in medium conditioned for 48 h by preadipocyte cultures relative to those not receiving GH. Immunocytochemical data indicated that IGF-I is synthesized by presumptive and mature adipocytes. The effect of GH on iIGF-I secretion was observed in cultures derived from both fetal and postnatal animals, while secreted IGF-binding protein activity was increased due to GH only in cultures from fetal animals. The increase in local IGF-I production in response to GH was associated with a decrease in adipocyte development, suggesting that local IGF-I may contribute to suppression of differentiated phenotype.

Selectivity of phospholipase C phosphorylation by the epidermal growth factor receptor, the insulin receptor, and their cytoplasmic domains

Phosphatidylinositol-specific phospholipase C isozyme gamma (PLC-gamma, Mr 145,000) is an excellent substrate for the epidermal growth factor (EGF) receptor both in vivo and in vitro. PLC-beta-1, another PLC isozyme, is a poor substrate for the EGF receptor. We examined the relative phosphorylation of PLC-gamma and PLC-beta-1 by the 170-kDa native EGF receptor molecule, the 66-kDa cytoplasmic kinase domain of the EGF receptor (Arg647-Ala1186), the alpha 2 beta 2 native insulin receptor, and the 48-kDa cytoplasmic kinase domain of the insulin receptor beta subunit (Gly947-Ser1343). Similar to the intact EGF receptor, the cytoplasmic kinase domain of the EGF receptor preferentially phosphorylated PLC-gamma. High-performance liquid chromatographic comparison of tryptic phosphopeptides from PLC-gamma phosphorylated by both forms of the EGF receptor kinase indicated similar patterns of multiple tyrosine phosphorylations. These results imply that substrate selectivity, at least in terms of PLC isozymes, is independent of the extracellular ligand-binding and membrane anchor domains of the EGF receptor. In comparison, neither the intact insulin receptor nor the beta-chain kinase domain was able to phosphorylate PLC-gamma to a significant extent. Also, insulin failed to stimulate the phosphorylation of PLC-gamma in NIH 3T3/HIR cells, which overexpress the human insulin receptor. Thus PLC-gamma is not a phosphorylation substrate for the insulin receptor in vitro or in the intact cell.

Phosphorylation of phospholipase C-gamma by cAMP-dependent protein kinase

The mechanism by which cAMP modulates the activity of phosphoinositide-specific phospholipase C (PLC) was studied. Elevation of cAMP inhibited both basal and norepinephrine-stimulated phosphoinositide breakdown in C6Bu1 cells which contain at least three PLC isozymes, PLC-beta, PLC-gamma, and PLC-delta. Treatment of C6Bu1 cells with cAMP-elevating agents (cholera toxin, isobutylmethylxanthine, forskolin, and 8-bromo-cAMP) increased serine phosphate in PLC-gamma, but the phosphate contents in PLC-beta and PLC-delta were not changed. In addition, cAMP-dependent protein kinase selectively phosphorylated purified PLC-gamma among the three isozymes and added a single phosphate at serine. The serine phosphorylation, nevertheless, did not affect the activity of PLC-gamma in vitro. We propose, therefore, that the phosphorylation of PLC-gamma by cAMP-dependent protein kinase alters its interaction with putative modulatory proteins and leads to its inhibition.

The effect of radial keratotomy (RK) combined with double Ruiz procedure on the corneal curvature

Under the postulation that the double Ruiz procedure could increase the effect of radial keratotomy (RK), RK combined with horizontal and vertical Ruiz procedure was performed in three groups of 22 rabbit eyes. In the group A of six eyes, RK with vertical Ruiz procedure was performed, and eight weeks later horizontal Ruiz procedure was added. In the group B of eight eyes, RK with horizontal Ruiz procedure was performed, and four weeks later vertical Ruiz procedure was added. In the group C of eight eyes, RK with horizontal and vertical Ruiz procedure was performed simultaneously. As a control, in the group D of eight eyes, RK without Ruiz procedure performed. Changes in keratometry for four weeks and eight weeks postoperatively were analyzed. The results were as follows: 1. At eight weeks postoperatively, mean changes in keratometry were 6.434D, 3.663D, 4.030D and 1.585D in groups A, B, C and D, respectively. 2. Mean changes in keratometry of groups A, B and C were significantly higher than that of group D. 3. Mean changes in keratometry of 6.434D in group A was significantly the highest of the three groups in which double Ruiz procedure was performed. For the above results, it was concluded that double Ruiz procedure increased the effect of RK, and the procedure was more effective when the secondary Ruiz procedure was added eight weeks later.

Characterization of age-related malondialdehyde oxidation: the effect of modulation by food restriction

Age-related in vitro malondialdehyde (MDA) oxidation by liver was investigated. It was established that mitochondria are the major site of oxidation, and that the oxidation process was catalyzed by aldehyde dehydrogenase as indicated by inhibitory action of disulfiram. The reaction of MDA oxidation requires Mg2+ and NAD as cofactors. The capacity for MDA oxidation was progressively lost with increasing age and the extent of the loss was modulated by food restriction.

Polyphosphoinositides produced by phosphatidylinositol 3-kinase are poor substrates for phospholipases C from rat liver and bovine brain

The ability of three pure types of bovine brain phospholipase C (PLC) and one pure rat liver PLC to utilize as substrates the recently discovered phosphatidylinositol 3-phosphate (PI-3-P), a putative phosphatidylinositol 3,4-bisphosphate (PI-3,4-P2), and phosphatidylinositol trisphosphate (PIP3) was investigated. PI-3-P, PI-3,4-P2, and PIP3 are the products of phosphorylation of PI, PI-4-P, and PI-4,5-P2, respectively, by phosphoinositide 3-kinase activities that are associated with certain protein-tyrosine kinases. Although these new phospholipids have been found in intact cells, PI-3,4-P2 and PIP3 appear only after stimulation of quiescent cells with growth factors such as platelet-derived growth factor (Auger, K. R., Serunian, L. A., Soltoff, S. P., Libby, P., and Cantley, L. C. (1989) Cell 57, 167-175) and after transformation by certain oncoproteins (L. A. Serunian, K. R. Auger, T. M. Roberts, and L. C. Cantley, manuscript in preparation). Mixtures of [3H]PI-4-P plus [32P]PI-3-P or [3H]PI-4,5-P2 plus [32P]PI-3,4-P2 or PIP3 alone were used as substrates for PLCs in vitro. After incubation with enzyme followed by extraction with chloroform/methanol/HCl, the ratio of 3H/32P in the aqueous layer revealed the selective hydrolysis of PI-4-P and PI-4,5-P2 over PI-3-P and PI-3,4-P2. High performance liquid chromatography analysis of the aqueous layer containing reaction products confirmed that only PI-4-P and PI-4,5-P2, were hydrolyzed to inositol 1,4-P2 and inositol 1,4,5-P3, respectively. These findings suggest that the turnover of PI-3-P, PI-3,4-P2, and PIP3 occurs independently of the turnover of PI-4-P and PI-4,5-P2.

Cyclic and noncyclic inositol phosphates are formed at different ratios by phospholipase C isozymes

The cyclic inositol phosphate content in the product of PLC-beta, gamma, and delta mediated cleavage of three phosphoinositides, PtdIns, PtdIns(4)p, and PtdIns(4,5)P2, was measured under several different experimental conditions. The ratio of cyclic to noncyclic product generally decreased in the order PLC-beta greater than PLC-delta greater than PLC-gamma. For all three enzymes the ratio decreased in the order PtdIns greater than PtdIns(4)P greater than PtdIns(4,5)P2. For all combinations of the three enzymes and three substrates cyclic product content was always higher at pH 5.5 than at pH 7.0. The effect of Ca2+ on the ratio of cyclic to noncyclic was also measured. The ratio remained constant between 0.5 microM and 2 mM for PtdIns. For PtdIns(4)P and PtdIns(4,5)P2, the ratios were unchanged between 0.5 and 500 microM, but increased abruptly at millimolar Ca2+ concentrations.

Stage-specific detection of a DNA-binding protein for the storage protein gene of Sarcophaga peregrina

A nuclear extract of fat body prepared from third instar larvae of Sarcophaga peregrina (flesh fly) was found to contain a DNA-binding protein that specifically bound to 5'-upstream region of the storage protein (arylphorin) gene. This protein was found only in larvae harvested 46 h after larval emergence, indicating that its appearance was strictly regulated by the developmental stage of the insect. Since the storage protein gene is actively transcribed in the fat body at this stage, this protein is probably a specific transcription factor for the storage protein gene. DNase I footprinting analysis showed that the nucleotide sequence of the binding site of this protein is ACCACAACA, which is located at residues -247 to -255 upstream of the +1 site. Results indicated that formation of the DNA-protein complex required Zn2+.

C-reactive protein, sialic acid and adenosine deaminase levels in serum and pleural fluid from patients with pleural effusion

Laboratory analysis of pleural fluids is essential to determine underlying diseases. The authors evaluated the clinical significance of C-reactive protein (C-RP), sialic acid (SA), and adenosine deaminase (ADA) determinations in sera and pleural fluids from 37 patients with pleural effusion. (FP12)C-RP and sialic acid levels and ADA activities were higher in exudates than in transudates of pleural fluids. Serum and pleural fluid C-RP levels were high in patients with pyothorax. Determinations of serum sialic acid and the pleural fluid to serum ratio were useful for the differential diagnosis of pulmonary tuberculosis and malignancy. ADA activities of pleural fluid and serum are useful for the differentiation of malignancy from tuberculosis and nonspecific pyothorax. C-RP concentrations of pleural fluid correlated to serum levels. However, concentrations of sialic acid and ADA activities were not correlated to serum levels and only correlated to protein concentrations of pleural fluids.

GH secretory dynamics and responsiveness to SMS 201-995 treatment in acromegaly

Recently, SMS 201-995, a long acting somatostatin analogue, has been used in successful therapy for inhibition of growth hormone (GH) levels in acromegaly. But, it was reported that inhibitory and clinical effects in the individual patient were different in many cases. Therefore, to find the predictive factor for patients with effective inhibition of GH, we investigated the paradoxical response to thyrotropin releasing hormone (TRH), growth hormone releasing hormone (GHRH) and diurnal variation of GH secretion between responders and non-responders to SMS 201-995. The results were as follows; Responders, patients with suppressive response to SMS 201-995, totalled 4 of 8 patients. The paradoxical response of GH to TRH was observed in 3 of 4 responders and 3 of 4 non-responders. The response of GH to GHRH was not noted in either of the groups. The diurnal variation of GH secretion showed in one of the responders and in 3 of the non-responders. These results suggested that the absence of diurnal variation of GH secretion was a characteristic feature of responders to SMS 201-995 and thus diurnal variation of GH secretion could be used as a predictive factor for SMS 201-995 therapy, and the pathogenetic mechanism of acromegaly might be dependent on the controlled regulation of GHRH and endogenous somatostatin.

The effect of long acting somatostatin analogue SMS 201-995 in acromegaly

Somatostatin is a potent inhibitor of the growth hormone (GH) secretion. However, the short half-life as well as the rebound phenomenon have rendered it impractical for therapeutic use. SMS 201-995, a long acting somatostatin analogue, has been shown to have a long acting inhibitor effect on GH secretion. To observe its suppressive effect on GH secretion and to determine whether it has a diabetogenic effect and whether it can suppress the paradoxical response of GH, we administered 50 μg of SMS 201-995 subcutaneously to five acromegalic patients before breakfast. Serum GH was reduced 85% from the basal concentration four hours after the administration of SMS 201-995 and remained below the basal level for up to eight hours without a rebound phenomenon. The pattern of glucose intolerance was observed in 4 out of 5 patients but not in the normal controls; it seemed to be caused by exessive GH. Also SMS 201-995 did not suppress postprandial insulin and glucagon secretion. In addition, we observed that SMS 201-995 suppressed the paradoxical release of GH to TRH in two of three patients who showed a paradoxical response. Unexpectedly one patient who had no paradoxical response before the administration of SMS 201-995 showed a paradoxical response. In conclusion, we suggest that more than 50 μg of SMS 201-995 should be given at least 3 times a day for adequate adjunctive therapy of acromegaly. The SMS 201-995 has no diabetogenic effect.

Effect of naloxone on counter insulin hormone secretion in insulin-induced hypoglycemia

To investigate the normal physiologic role of endogenous opiates in glucose homeostasis and as a preliminary study for clarifying the association of endogenous opites with pathophysilogy of NIDDM, we obseved the changes in the secretion of counter-insulin hormones in response to insulin-induced hypoglycemia with or without naloxone.

The results were as follows: Blood glucose was decreased significantly more rapidly with naloxone infusion than after insulin alone, which seems to play a role in the early responses of ACTH and GH. Not only was the more rapid response of ACTH and GH, but also the prolonged secretion of ACTH and Cortisol were observed after administration of insulin and naloxone.

We concluded that endogenous opiates may be involved in the feedback regulation of secretion of ACTH and GH during hypoglycemia either at hypophysis or hypothalamus, and involved in glucose homeostasis via a certain direct mechanism other than regulation of counter hormone secretion.

Possible correlation between non-insulin dependent diabetes mellitus (NIDDM) and restriction fragment length polymorphism (RFLP) of the 5'-flanking region of insulin gene in Korean diabetic population

Restriction fragment length polymorphism (RFLP) is a new and precise method for the detection of the disease on the molecular level. The genetic background of Non-insulin dependant diabetes mellitus (NIDDM) has been strongly suggested, but its occurrences are obvious for other expession factors. We first investigated insulin gene polymorphism in twenty-nine Korea NIDDM patients and 11 non-diabetic controls. We found 91 percent and 86 percent of the genotype 1/1 in diabetics and controls respectively. Also genotype 1/3 was found 9 percent and 14 percent each in both groups. Genotype 3/3 revealed 0 percent in two groups. Four acromegalics who had secondary DM showed only genotype 1/1. These findings showed that class 3 allele(2.4 kb) was a weak genetic marker of NIDDM, and had a faint correlation.

Hepatitis B viral markers in pregnant women and newborn infants in Korea

A study of the 5,284 pregnant women who delivered at St. Columban’s Hospital in Mokpo City between April 1, 1985 to June 30, 1987 was conducted to determine the presence of hepatitis B viral (HBV) markers in the mothers and infants and to evaluate their effects. Medical histories, physical examinations, liver function studies and the ELISA test for HBV markers were reviewed. The following results were obtained: 1. Of the 5,284 pregnant women, 448 (8.48%) were positive for HBsAg. Three hundred and thirty four women tested positive for HBsAg; 130 (38.92%) were HBeAg positive, 105 (31.44%) were HBeAg and anti-HBe negative, and 99 (29.64%) were anti-HBe positive. 2. Women positive for HBsAg exhibited a slight increase in toxemia (p<0.1), and no significant difference in postpartum hemorrhage (0.05< p <0.1) and the severity of hyper-emesis. 3. SGPT was significantly higher in HBeAg positive women than in HBeAg negative women (p<0.01), and it was significantly more elevated in both eclamptic and preeclamptic women than in normal pregnant women (p<0.005). 4. The frequency of congenital malformation, spontaneous abortion, infantile death and physiologic jaundice was increased in the newborns of chronic HBV carriers, while women with active hepatitis B experienced more premature births. 5. Mother to infant transmission of HBsAg and HBeAg was high in the HBeAg positive group (18.0%, 42.7%) respectively, but very low in the HBeAg negative group (7.8%, 0.0%). Mother to infant transmission of antibodies was in the order of anti-HBc (95.5%), anti-HBe (91.2%) and anti-HBs (75.0%). The effects of the HBV carrier state in pregnant women included increases in toxemia, postpartum hemorrhage, congenital malformations and premature births, however none of them were statistically significant. There was a significant difference in the elevation of SGPT between toxemic and normal pregnant women, and between HBeAg positive and HBeAg negative carrier women. The mother to infant transmission rate of HBeAg was more frequent than that of HBsAg.

Epidemiologic study of hepatitis B in pregnant Korean women

The positive rates of hepatitis B viral markers according to many epidemiologic factors were analyzed in 2,873 pregnant women who delivered at St. Columban’s Hospital in Mokpo City from April 1st, 1985 to March 31st, 1986.

The following results were obtained: The overall HBsAg positivity in all pregnant women was 8.3%. The positive rate of HBsAg was unrelated to age. It was 13.2% in the 11–20 year age group. 12.5% in the 31–40 year age group, 7.8% in the 21–30 year age group and 0.0% in the 41–50 year age group. The positive rate of HBsAg was slightly related to locality. It was a little higher in women who grew up in rural areas (8.6%) than in urban areas (7.7%). The positive rate of HBsAg was unrelated to educational background. The positive rate of HBsAg was unrelated to economic status. It was 8.7% in the highest income group and 8.6% in the lowest income group. The positive rate of HBsAg was higher in cases who had injections more than four times. The positive rate of HBsAg was higher, but not significantly, in cases who had received blood transfusion. The positive rate of HBsAg was higher, but not significantly, in cases who had more than three siblings (0.05

Collapse

Studies on changes of beta-adrenergic receptors in polymorphonuclear cell and mononuclear cell with the changes of thyroid function

Although it has been well established that thyroid hormones increase β-adrenergic receptors of various tissues in the animal studies, there are controversies about the β-adrenergic receptor changes of human mononuclear cells and polymorphonuclear cells. The present study was performed to analyze the change of β-adrenergic receptor of those cells according to the thyroid functional status and to evaluate their usefulness in assessment of sympathetic hyperactivity. We measured [³H]-dihydroalprenolol binding to circulating mononuclear and polymorphonuclear cells from 18 patients with hyperthyrodism, 7 with hypothyroidism, 8 with euthyroid goiter and 21 normal controls. Only with polymorphonuclear cells the receptor concentration was significantly higher (P<0.01) in hyperthyroidism (46.07±4.78 fmol/mg protein) than in the normal control (28.42±2.06 fmol/mg protein) and the affinity constants of both cells were comparable to normal control values. And serum concentrations of T₃ were not correlated well with the changes of receptor concentrations in hyperthyroidism. The patients with hypothyroidism and euthyroid goiter showed no significant difference in the receptor concentration and the affinity constants with both cell binding assays. These results indicate that thyroid hormones increase the receptor concentration in polymorphonuclear cells which might be responsible for the symptoms of sympathetic hyperactivity and the polymorphornuclear cells are useful for β-adrenergic receptor assay.

Postprandial 2-hr C-peptide concentration as a guide for insulin treatment in patient with NIDDM

To determine the usefulness of postpradial-2hr serum C-peptide as a guide for insulin treatment in NIDDM, the 67 NIDDM patients admitted in Kyung Hee University Hospital from Nov. 1981 to May 1984 were classified according to postprandial 2-hr insulin, C-peptide levels and 24-hr urine C-peptide levels. The patients were divided into 3 groups according to the level of insulin or C-peptide in normal persons reported previously. In 22 patients with postprandial 2-hr values of more than 5.8 ng/ml for C-peptide, 12 patients (55%) were diet controllable and only 5 patients (22%) required insulin treatment. On the other hand, in the classification according to postprandial 2-hr insulin or 24-hr urine C-peptide levels, higher response groups should be controlled by diet alone, but 9 of 18 patients (50%) for insulin, 8 of 14 patients (57%) for 24-hr urine C-peptide required insulin treatment. The classification according to postprandial 2hr C-peptide levels was a more sensitive guide for insulin treatment than that with postprandial 2hr insulin level or 24hr urine C-peptide level.

The changes of serum-ACE, plasma renin activity and aldosterone in the diabetics with hypertension

It is well known that the serum-ACE levels are elevated in sarcoidosis, Gaucher’s disease, and some granulomatous diseases. Recently, the serum-ACE level was also found to be elevated in diabetes mellitus. To confirm the possible role of plasma renin activity and aldosterone in the pathogenesis of hypertension and to assess the relationship of serum ACE to the plasma renin activity and aldosterone profiles in diabetics, we measured the levels of serum ACE, plasma renin activity, aldosterone and blood pressure in 38 diabetic patients who were admitted to Kyung Hee University Hospital from June 1981 to September, 1982. The results were as follows: The S-ACE activity was significantly elevated in 38 patients with diabetes mellitus (9.42±6.60 Unit) as compared with that in the healthy controls (2.53±1.54 Unit) (p<0.005) (p<0.005). The S-ACE activity was significantly elevated in 15 hypertensive diabetics (14.29± 7.10 Unit) as compared with that in 23 normotensive diabetics (6.24±3.68 Unit) (p<0.005). The S-ACE activity was elevated in 15 diabetic patients with retinopathy (10.6±4.7 Unit) as compared with the levels in 17 diabetic patients without retinopathy (6.7±4.8 U) (p<0.05). The S-ACE activity was directly correlated to the mean arterial pressure (r=0.54) (p<0.005). The plasma renin activity and aldosternone concentrations in diabetics were not different from the normal controls and had no correlationship to the S-ACE activity. After 2 weeks of insulin therapy in 15 diabetics, the S-ACE activity was not changed.

Synthesis of the transferrin receptor by cultures of embryonic chicken spinal neurons

We have purified a glycoprotein from chicken sciatic nerves, sciatin, which has pronounced trophic effects on avian skeletal muscle cells in culture. Recent studies have shown that sciatin is identical to the iron-transport protein, transferrin, in terms of its physicochemical structure, immunological reactivity, and biological activity. To determine whether transferrin is synthesized and released by neuronal tissue, we incubated cultures of dissociated chicken spinal neurons in a medium free of L-leucine containing either L-3H-amino acids or L-[14C]leucine and immunoprecipitated transferrin with highly specific antibodies. The radiolabeled protein precipitated by rabbit heteroclonal, goat heteroclonal, or mouse monoclonal antitransferrin antibodies increased in specific activity in a linear manner for at least 30 min. Synthesis of this protein was abolished by the presence of puromycin (20 micrograms/ml) or cycloheximide (10(-5) M). The disappearance of the radiolabeled protein from cells was linear with a half-life (t 1/2) of 8-10 h. When immunoprecipitates were separated by SDS gel electrophoresis, a prominent band corresponding to transferrin (Mr 84,000) was visualized by staining with Coomassie Blue. However, when such gels were fluorographed, no radioactivity was apparent in the transferrin region of the gel although a prominent radioactive band was visualized at an Mr of 56,000. The protein of Mr 56,000 was not simply a degradation product of transferrin because this particular protein band was not generated by incubating radiolabeled transferrin with unlabeled neuronal homogenates. The protein of Mr 56,000 was purified from embryonic chicken brain and spinal cord by immunoabsorption chromatography on mouse monoclonal antitransferrin IgG conjugated to Sepharose 4B followed by affinity chromatography on immobilized transferrin. The purified protein bound radioiodinated transferrin and was precipitated by rabbit anti-chicken transferrin-receptor antibodies. Furthermore, this receptor protein was found to be localized on the plasma membrane of dorsal root ganglion neurons by immunocytochemistry using the peroxidase-antiperoxidase technique, and by blocking experiments, which showed that antitransferrin receptor IgG could inhibit the binding of fluorescein-conjugated transferrin at 4 degrees C to cultured neurons in vitro. From these data, we conclude that transferrin is not synthesized by cultures of chicken spinal cord neurons, but that the receptor for transferrin is synthesized by these cultures and is precipitated by antitransferrin antibodies as an antigen-receptor complex.

Spermiogenesis and testicular spermatozoa of the olive baboon (Papio anubis)

The ultrastructure of spermiogenesis and of testicular spermatozoa of the olive baboon (Papio anubis) has been studied. The four main (Golgi, cap, acrosome and maturation) phases of spermiogenesis are described, and these phases have been further subdivided into a total of ten phases. Spermiogenesis was found to be basically similar to that of other mammalian species, in particular to that of man. A lower number of morphologically deviating cells was found in the baboon, but in other respects most differences between human and baboon spermiogenesis and spermatozoa refer to dimensions. Aspects of the morphogenesis of certain structures of the tail are discussed in more detail.

Study of ventilation testing with electronystagmography

Provocation tests such as head shaking and positional tests, as well as hyperventilation, have been used routinely by many laboratories to elicit nystagmus during an electronystagmogram. We added oxygen testing to this routine battery and compared the results with hyperventilation and other forms of provocative testing. Hyperventilation and oxygen testing are unique in that they probably affect the vestibular system by changing the levels of oxygen and carbon dioxide supplied. Hyperventilation in theory would decrease available oxygen, while oxygen testing would cause an increase. In a study of two groups totaling over 700 patients, we found that oxygen testing is only occasionally positive (2.5%) and is of little practical value. Hyperventilation testing is positive 8% of the time but rarely alone, and has no localizing value. When hyperventilation and oxygen tests are both positive, the nystagmus may be in opposite directions. In 6 of 18 patients with acoustic neurinomas, hyperventilation produced transitory direction-changing nystagmus.

Etidocaine used for retrobulbar block: a comparison with lidocaine

Fifty patients in a double-blind study received in randomized fashion either etidocaine HCl (Duranest) 1% or lidocaine HCl (Xylocaine) 2% with epinephrine 1:200,000 in a retrobulbar block for cataract surgery. Two parallel groups of 25 patients each were studied comparing the clinical properties of the drugs. The onset time for sensory and motor blocks of both drugs was essentially the same (3 minutes). The duration of action of etidocaine was considerably longer than lidocaine and less postoperative pain medication was required by patients blocked with etidocaine.

The ultrastructure of mink (Mustela vision) spermatozoa

The subcellular structure of epididymal spermatozoa obtained from standard dark mink was studied. Conventionally prepared thin sections were observed under a transmission electron microscope. The mink spermatozoan head showed six swellings on the dorsoventral aspects: two connected hump-like swellings at the anterior border of the equatorial segment of the acrosome, and one at the post acrosomal sheath on each side. These swellings are a species-specific structural feature which might be necessary for recognition of the ovum or attachment to it in fertilization. The neck appeared to show a dorsoventrally continuous but laterally separated capitulum which was followed by two major and five minor columns, forming at first a striated ring and then joining with the dense fibers of the axial fiber bundle. The dense fibers numbered 9, 1,5, and 6 were larger than the rest. In the axonemal complex, subfiber A was larger than the central fiber, while subfiber B was the smallest. The middle piece was of medium length when compared with other mammalian spermatozoa. The shape of the annulus was triangular in longitudinal sections. The occurrence of swellings anterior and posterior to the equatorial segment of the head and the arrangement of the connecting piece, the modified capitulum, and the grouping of the striated columns are some of the important features of mink spermatozoa.