Random chimeragenesis of G-protein-coupled receptors. Mapping the affinity of the cAMP chemoattractant receptors in Dictyostelium

G-protein-coupled receptors mediate a wide variety of responses to extracellular stimuli in eucaryotic cells. Binding of the ligand to these receptors is thought to involve contacts within a pocket from the sequences of these genes. A family of four surface cAMP receptors that mediate responses to secreted cAMP coordinates the developmental program of Dictyostelium. A large difference in affinity for cAMP exists between cAR1 (25 and 230 nM) and cAR2 (> 5 microns). To understand the basis for this affinity difference, we generated an extensive series of cAR1/cAR2 and cAR2/cAR1 chimeras using a technique designated "random chimeragenesis." When a linearized plasmid was transformed into Escherichia coli, tandemly positioned cAR1 and cAR2 genes crossed over at homologous regions. The cAMP binding properties and EC50 values for agonist-induced phosphorylation of each of the chimeras were characterized in order to map the domains that determine the affinity. These studies implicated a domain in the second extracellular loop in which only 5 residues differ between the two receptors as the major determinant of affinity. A secondary domain including residues 110-147 (11 residue differences) was identified as a minor determinant of affinity.

Comparative vascular effects of midazolam and lorazepam administered during cardiopulmonary bypass

We studied the comparative vascular effects of midazolam and lorazepam in 52 patients undergoing elective cardiac surgery procedures. After administration of fentanyl, 100 micrograms/kg intravenously, the patients were randomized to receive either midazolam 0.1 mg/kg (M high), midazolam 0.05 mg/kg (M low), lorazepam 0.1 mg/kg (L high), lorazepam 0.05 mg/kg (L low), or placebo during cardiopulmonary bypass (CPB). Compared to the placebo and L-low groups, the high-dose midazolam group had more effect on systemic vascular resistance (SVR) starting at 5 min after study drug administration (P < 0.02). M high and L high required increased quantities of phenylephrine administered to maintain the mean arterial pressure (MAP) at > 50 mm Hg after rewarming and removal of the aortic cross-clamp (P < 0.03). In the first 12 h of the postoperative period, the M-high group required phenylephrine (PHE) infusion for hypotension associated with decreased SVR more often than placebo (8/10 vs 1/11 patients, P < 0.008, chi 2). In conclusion, midazolam more effectively attenuated the increase in SVR that occurred during CPB than patients receiving either placebo or lorazepam. The hemodynamic effects from a single dose of 0.1 mg/kg midazolam administered at the start of CPB may persist into the postoperative period.

Tc-99m MIBI uptake in simultaneous thyroid and lung cancers

The authors present a patient with simultaneous follicular thyroid and small-cell lung cancers, both of which showed Tc-99m MIBI uptake. CT scans showed two masses: one involving the right lower neck including the right supraclavicular area and the right superior mediastinum, and the other involving the peripheral portion of the right upper lobe of the lung. I-131 imaging showed increased uptake in the right neck mass only. Tc-99m MIBI imaging, which was performed for evaluation of chest pain, showed intense uptake in the neck mass (tumor to heart ratios in planar and tomographic images were 0.92 and 0.96, respectively), and less uptake in the lung mass (tumor to heart ratios in planar and tomographic images were 0.53 and 0.40, respectively). Biopsy of the right supraclavicular mass revealed a follicular carcinoma, and a bronchoscopic biopsy of the right upper lobe mass revealed a small cell carcinoma.

Characterization of plasma and intracellular membrane prolactin receptor in lactating mouse mammary cells

Mammary cells were prepared from lactating mice by collagenase digestion in order to examine the reaction of prolactin (PRL) with its cellular receptors. Cells were treated with 10% acetic acid following PRL binding. Between 5 and 12.5% acetic acid, the dissociation of PRL remained constant. The ratio of dissociated PRL was comparable to that of tissue slices or disrupted cells with this treatment. In subcellular membranes, about 81% of PRL bound to plasma membrane receptors was dissociated by acid treatment while PRL dissociated from intracellular membrane receptors was about 21%. Based on the nature of their PRL dissociation, PRL receptors were classified as acid-sensitive or acid-insensitive. The reaction of PRL with either species was reversible and saturable, and was dependent on temperature and time. Both species showed high PRL-binding affinity. However, acid-insensitive receptor was unstable at 37 degrees C. The level of acid-sensitive receptor was close to that of acid-insensitive receptor in late pregnancy. During the first 3 days of lactation, the level of acid-sensitive receptor increased more slowly than that corresponding to acid-insensitive receptor. The above criteria suggest that the postpartum increase in PRL binding is characterized especially by an increase in the level of acid-insensitive PRL receptor located mainly on intracellular membrane.

A case of extra-hepatic portal hypertension caused by periportal tuberculous lymphadenitis

This report describes a case of portal hypertension caused by periportal tuberculous lymphadenitis. There were a few reports of portal hypertension associated with tuberculosis. A 27-year-old man was admitted to the hospital because of recurrent hematemesis for 7 days. There was a history of mediastinal tuberculous lymphadenitis 3 years earlier that was treated with isoniazide, rifampin, ethambutol, and pyrazinamide for 2 years. Clinical evaluation revealed esophageal variceal bleeding and main portal vein obstruction by enlarged periportal lymph nodes. The patient underwent distal splenorenal shunt. Pathologic examination of the excised periportal lymph node revealed chronic granulomatous inflammation with central caseous necrosis. Thereafter the patient took antituberculous medication for 12 months. The patient has not re-bled 3 years since the shunt operation.

Pathologic changes after inferior oblique marginal myotomy in rabbits

To evaluate the histopathologic changes after an inferior oblique marginal myotomy with local injection of triamcinolone, an inferior oblique marginal myotomy was performed in 14 white rabbits and they were divided into 2 groups, one group with a local injection of triamcinolone and the other group without triamcinolone injection after a myotomy. At the postoperative one month, an edema of the muscle fibers and an infiltration of the inflammatory cells were observed and at postoperative three months, a fibrous tissue ingrowth around the muscle fibers and an atrophy of the muscle fibers were found and those changes were less prominant in the group with triamcinolone injection. The local injection of triamcinolone after the inferior oblique marginal myotomy would help in decreasing the fibrous tissue ingrowth and the formation of the scar tissue, thus it could be used in augmenting the effect of the inferior oblique marginal myotomy.

A clinical study of benign focal amyotrophy

We reviewed the clinical, electrophysiological, radiological, and histopathological findings in 25 patients with benign focal amyotrophy. There were 14 patients with upper limb type and 11 with lower limb type. 18 patients had unilateral involvement and 7 had bilateral involvement asymmetrically. The characteristics clinical features were sporadic occurrence, predominance in young males, nonprogressive course or initial progression for 1 to 3 years followed by stationary state, segmental distribution of muscle weakness and atrophy localized to one limb or both homologous limbs markedly asymmetrically, and absence of any definite sensory loss or central nervous system involvement. The electrophysiological, radiological, and muscle histopathological findings suggested chronic focal anterior horn cell disease. Although the prevalence of this disease is still unknown, the importance of recognition is being emphasized because of its common occurrence in our country and the benign prognosis.

A case of giant hemangioma of the liver presenting with fever of unknown origin

A 37 year-old-woman was admitted to the hospital because of 15 days' duration of continuous fever. Routine studies for detection of fever foci were negative. Imaging studies revealed giant hemangioma of the liver with central thrombosis. The fever persisted for a period of 4 weeks, and subsided after conservative management. We report a case of hepatic hemangioma presenting with fever of unknown origin. The condition is very rare, but should be regarded as one of the causes of fever of unknown origin.

Localization of ligand-induced phosphorylation sites to serine clusters in the C-terminal domain of the Dictyostelium cAMP receptor, cAR1

When Dictyostelium cells are stimulated with cyclic adenosine 3',5'-monophosphate (cAMP), the major surface cAMP receptor expressed in early development, cAR1, undergoes a rapid phosphorylation and parallel decrease in electrophoretic mobility which may serve to regulate the activity of this G protein-coupled receptor. Biochemical analyses indicate the electrophoretic mobility shift is caused by phosphorylation of serine residues within the C-terminal cytoplasmic domain. The 18 serines of this domain are grouped in four clusters, designated 1 to 4 (in N- to C-terminal order). Two approaches were taken to determine the distribution of phosphorylation sites among the serine clusters. First, a proteolytic analysis of the C-terminal domain was performed. Second, mutants lacking various combinations of the serine clusters were created by site-directed mutagenesis and their abilities to undergo ligand-induced modification were determined. Both approaches yielded corroborative results consistent with the following model: the stimulus induces the addition of approximately two phosphates to cluster 1 and one to cluster 2; basal phosphorylation occurs predominantly in cluster 3 and to a lesser extent in cluster 2; and cluster 4 is not phosphorylated. The phosphorylation-deficient receptor mutants should be useful for establishing the role of ligand-induced phosphorylation of cAR1 in chemotaxis, cell-cell signaling, and gene expression.

Crossing the SJL lambda locus into kappa-knockout mice reveals a dysfunction of the lambda 1-containing immunoglobulin receptor in B cell differentiation

Mice of the SJL strain produce approximately 50 times less serum lambda 1 immunoglobulin light chains than other mouse strains. The defect is genetically linked to the lambda locus, but it is unknown whether it is due to regulatory alterations or known structural changes. We find no mutation in the SJL lambda 3-1 enhancer which regulates both lambda 1 and lambda 3. To investigate the defect further, the production of lambda light chains was amplified by crossing SJL with kappa-knockout mice. In kappa-knockout mice with the wildtype lambda locus (kappa -/- lambda +/+), the majority of serum light chains are lambda 1. In contrast, kappa-knockout mice with the SJL lambda locus (kappa -/- lambda s/s) show a pronounced expression of lambda 2 and lambda 3, with only some expression of lambda 1. The results show that the SJL defect is lambda 1 specific, since the linked lambda 3 expression is normal. As the transcription and rearrangement of lambda 1 appear normal in SJL, the defective lambda 1 synthesis is most likely due to a point mutation in the lambda 1 constant region resulting in a glycine to valine substitution. At the cellular level, in kappa-knockout mice with the SJL lambda locus there are fewer immature, and especially mature, lambda 1 B cells and the production of lambda 1 plasma cells is strongly inhibited. The lambda 1 specificity of the defect suggests that the point mutation in SJL C lambda 1 creates an immunoglobulin receptor complex which is dysfunctional in B cell differentiation.

The effects of mats on back and leg fatigue

Prolonged standing is common in many industrial workplaces. It is also quite common for workers to complain of discomfort in the back and legs as a result of prolonged standing. Mats are often provided for the worker to relieve this fatigue. However, there is no quantitative evidence that these mats relieve leg and back fatigue. Five subjects were asked to stand on a concrete surface and two mat surfaces for prolonged periods of time. Spectral electromyographic analyses indicated that mats reduced localized muscle fatigue in the erector spinae muscle only. Furthermore, this fatigue reduction occurred only with the more compressible of the two mats tested. These results imply that localized muscular fatigue in the leg may not be relieved with 'anti-fatigue' mats, and some of these mats only benefit the back.

Treatment outcome and prognostic factors of medulloblastoma

Medulloblastoma, once a tumor with a dismal prognosis, is one of the most common primary brain tumors of childhood. As the methods of treatment have been continuously refined, the outcome has improved remarkably during the last few decades. The outcome of 78 medulloblastoma patients, which were managed from 1972 to 1992 at the Department of Neurosurgery of Seoul National University Hospital, were analyzed to calculate the 3-year and 5-year survival rates (3yS and 5yS). Of those, 52 cases which were treated after July 1982 were studied 1) to calculate the 3yS and 5yS, 2) to figure out the prognostic factors of survival, and 3) to investigate the role of adjuvant chemotherapy ('8-drugs-in-a-day' protocol: CCNU, cisplatin, vincristine, hydroxyurea, procarbazine, cytosine arabinoside, methylprednisolone and cyclophosphamide). The 3yS and 5yS of the 78 patients were 57.4% and 47.3%, respectively. Of the 52 patients treated after July 1982, the 3yS and 5yS were 67.8% and 64.1%, respectively. The latest recurrence was at 56 months after surgery. All the recurrences were within the risk period of Collins' rule. Of the prognostic factors studied by univariate analysis (age, sex, Chang's classification T- and M-stages, extent of surgical removal, and chemotherapy), Chang's classification M-stage and sex were the statistically significant factors (p = 0.028 and 0.024 respectively). On multivariate analysis, only the M-stage was statistically significant (p = 0.004). Adjuvant chemotherapy had different influences in different patient groups. Only in the 'poor risk' group, did adjuvant chemotherapy have a strong tendency to better outcome (p = 0.069). Further data collection and analysis will lead to better treatment modalities and better outcome for this most common primary malignant brain tumor in childhood.

Expression of lambda and kappa genes can occur in all B cells and is initiated around the same pre-B-cell developmental stage

Transgenic mice that carry a lambda 2 transgene under the control of the V lambda 2 promoter and the E lambda 2-4 enhancer (lambda 2E lambda mice) are described. A high proportion of B cells in the spleen and the bone marrow express the lambda transgene on the cell membrane. lambda 2 protein is synthesized by all lambda 2E lambda-derived spleen B-cell hybridomas that have retained the transgene, suggesting that all B cells have the ability to express lambda genes. Feedback inhibition of endogenous kappa-gene rearrangement is significant, but not complete. The results are similar to those with transgenic mice expressing the same lambda 2 transgene under the control of the heavy-chain enhancer (lambda 2EH mice). Although the lambda 2EH transgene is expressed before the lambda 2E lambda transgene, feedback inhibition seems to occur at about the same stage of B-cell development, regardless of the timing of expression of the lambda transgenes. Apparently, feedback is not necessarily coincident with the assembly of a heavy-chain/light-chain complex in pre-B cells. Expression of lambda in the normal fetal liver coincides with the expression of kappa; thus, it appears that lambda-gene transcription is not delayed. The differential rearrangement of kappa and lambda genes is discussed in the light of these findings.

Effects of acupuncture on blood pressure and plasma renin activity in two-kidney one clip Goldblatt hypertensive rats

Shih-Hsüan [Sipseon (EX-UE-11)] are Curious loci lying outside of the meridians on the tips of each finger. These loci have long been the acupuncture sites for the treatment of cardiovascular disease in oriental medicine. Alterations in the renin-angiotensin system have been considered as the pathophysiological basis of the origin and/or maintenance of hypertension. Activation of the plasma or tissue renin-angiotensin system may be one of the cause of hypertension. The aim of the present study was to elucidate the effects of acupuncture on blood pressure and plasma renin activity. Acupuncture was applied on the EX-UE-11 of two-kidney one clip Goldblatt hypertensive rats. Both the systolic blood pressure and the plasma renin activity decreased significantly after treatment with acupuncture on the EX-UE-11. In the sham-operated and control rats, the procedure influenced the parameters without significant changes. The results suggest that the suppressive hemodynamic effect of acupuncture on the EX-UE-11 may be related to changes in plasma renin activity.

Immunoglobulin gamma 2b transgenes inhibit heavy chain gene rearrangement, but cannot promote B cell development

Transgenic mice with a gamma 2b transgene were produced to investigate whether gamma 2b can replace mu in the development of B lymphocytes. Transgenic gamma 2b is present on the surface of B cells. Young transgenic mice have a dramatic decrease in B cell numbers, however, older mice have almost normal B cell numbers. Strikingly, all gamma 2b-expressing B cells in the spleen also express mu. The same is true for mice with a hybrid transgene in which the mu transmembrane and intracytoplasmic sequences replace those of gamma 2b (gamma 2b-mumem). The B cell defect is not due to toxicity of gamma 2b since crosses between gamma 2b transgenic and mu transgenic mice have normal numbers of B cells. Presence of the gamma 2b transgene strongly enhances the feedback inhibition of endogenous heavy chain gene rearrangement. Light chain genes are expressed normally, and the early expression of transgenic light chains does not improve B cell maturation. When the endogenous mu locus is inactivated, B cells do not develop at all in gamma 2b transgenic mice. The data suggest that gamma 2b cannot replace mu in promoting the developmental maturation of B cells, but that it can cause feedback inhibition of heavy chain gene rearrangement. Thus, the signals for heavy chain feedback and B cell maturation appear to be different.

The effect of extracapsular cataract extraction using nucleus dislocation into anterior chamber on the corneal endothelium

When the continuous circular capsulorhexis (CCC) is being performed, the nucleus delivery using nucleus dislocation into the anterior chamber is safer and easier than using conventional "push and pull" method to maintain an intact lens capsule. This method include such procedures that after CCC, the nucleus being freed in the capsular bag by hydrodissection and hydrodelineation, then hooked with a Sinskey hook and drawn out to the anterior chamber by rotation. It may damage the corneal endothelium because of the manipulation in the anterior chamber. To investigate an effect of this method on the corneal endothelium, we performed two months time analysis of changes of the central corneal endothelial cell density (CECD) in two groups--a group with an extracapsular cataract extraction (ECCE) using nucleus dislocation into the anterior chamber and a group with a conventional ECCE. Eighteen eyes of 18 cataract patients who were operated on with ECCE using nucleus dislocation into the anterior chamber method, and ten eyes of 10 cataract patients who were operated on with a conventional ECCE method were included. The CECD was measured by specular microscopy, preoperatively, postoperatively at 1 month and 2 months. The average endothelial cell loss at postoperative 1 month was 7.20 +/- 2.98% in the experimental group and 7.88 +/- 2.93% in the control group, and at postoperative 2 months was 9.05 +/- 2.96% in the experimental group and 9.34 +/- 2.95% in the control group. The change in CECD between two groups was not statistically significant.

Isolation and analysis of the rat genomic sequence encoding Cu/Zn superoxide dismutase

A rat genomic DNA (SOD1) encoding Cu/Zn superoxide dismutase (SOD1) (superoxide; superoxide oxidoreductase, EC 1.15.1.1) was cloned and sequenced. The rat SOD1 gene consisted of five exons and four introns spanning about 6 kb. The transcription start point (tsp) was observed 93 bp upstream from the ATG codon by primer extension analysis. The 5'-flanking sequence of SOD1 contained two CCAAT box motifs, a TATA box and four GC-like boxes. In the 3'-flanking region of SOD1, a polyadenylation signal, consensus sequence YGTGTTYY, and a G/T cluster were observed. A rat identifier (ID) sequence, a repetitive element of the rat genome, was located at between 569 and 484 bp upstream from the tsp.

Effects of the par locus on the growth rate and structural stability of recombinant cells

A decreased growth rate of recombinant cells is observed when a cloned gene protein encoded in a multicopy plasmid is induced from a strong promoter. This negative effect on the cell growth rate may be the consequence of alternate use or reallocation of energy, precursor metabolites, and protein synthesizing machinery. In order to analyze the causes for this adverse effect, we have studied how genetic elements present in multicopy plasmids affect the growth of recombinant Escherichia coli (K12 delta H1 delta trpEA). Turning on of the PL promoter, whether or not protein-coding sequences were present downstream of the promoter, decreased the growth of the recombinant cells by 15-50%. This result suggests that the essential factor(s) for cell growth may be sequestered by the genetic elements present in the plasmids and thus may cause the decreased growth. The negative effect of the de-repressed PL promoters on cell growth was partially reversed when the par sequence from pSC101 was inserted into the same plasmid. In each case when the plasmid carried only the PL promoter, the PL promoter followed by the N-terminal part of the protein-coding region, or the PL promoter followed by complete sequences encoding a protein, the par sequence exhibited a positive effect on the growth rate of the recombinant cells, which usually grow at a slower rate than the host cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Gender differences in the individual characteristics and life contexts of late-middle-aged and older problem drinkers

This study focuses on gender differences in the individual characteristics and life contexts of late-life problem drinkers. Late-middle-aged women with drinking problems (n = 183) consumed less alcohol, had fewer drinking problems, and reported more recent onset of drinking problems than did their male counterparts (n = 476). They also used more psychoactive medications, were more depressed, and were less likely to seek alcohol treatment. Consistent with a gender role perspective on alcohol abuse, problem-drinking women had more family-related and fewer financial stressors than did problem-drinking men. Contrary to expectation, however, problem-drinking women reported more support from children, extended family members, and friends than did problem-drinking men. Moreover, women who continued to have drinking problems over a 1-year interval reported some unexpected short-term benefits at follow-up, including reduced spouse stressors. Women who had remitted at follow-up experienced less spouse support, and more family-related stressors and depression than did remitted men. They also lost support from extended family members over the 1-year interval. The results suggest a need for screening and treatment efforts tailored more closely to the life circumstances of women with late-life drinking problems.