Mechanism of the natriuretic action of gamma-melanocyte-stimulating hormone

To explore the mechanism underlying the natriuretic effect of gamma-melanocyte-stimulating hormone (gamma-MSH), we infused the peptide intravenously at 200 pmol/min into anesthetized rats. gamma-MSH led to a progressive increase in urinary sodium excretion (UNaV), whereas continuous infusion of the vehicle did not affect UNaV. Plasma immunoreactive gamma-MSH was nine times greater at 120 min after the start of the infusion than in vehicle-infused rats. Plasma atrial natriuretic peptide (ANP) concentration also increased as a consequence of the gamma-MSH infusion, and a strong correlation existed between the concentrations of the two peptides (n = 17, r = 0.81, P < 0.001). Urinary excretion of guanosine 3',5'-cyclic monophosphate and adenosine 3',5'-cyclic monophosphate increased as a result of the infusion. Antiserum to rat ANP blunted the natriuresis only slightly, suggesting that the increase in plasma ANP concentration was not a critical element in gamma-MSH natriuresis. gamma-MSH had no effect on ANP release from isolated rat right atrial strips superfused in vitro. Infusion of gamma-MSH (500 fmol/min) directly into one renal artery led to an ipsilateral natriuresis without change in UNaV from the contralateral kidney. Prior denervation of the infused kidney prevented the natriuresis resulting from intrarenal infusion. Intrarenal infusion of ANP (800 fmol/min) also produced ipsilateral natriuresis, which, however, was not affected by renal denervation. These studies confirm that the natriuretic action of gamma-MSH occurs primarily by an interaction with the renal nerves. Intravenous infusion of the peptide sufficient to produce a supraphysiological plasma gamma-MSH concentration also results in an increase in plasma ANP concentration; however, this increase at best plays only a minor role in the natriuresis following intravenous gamma-MSH infusion.

Characterization of Orientia tsutsugamushi isolated in Taiwan by immunofluorescence and restriction fragment length polymorphism analyses

A total of 10 strains of Orientia tsutsugamushi were isolated from field rodents and chiggers in Taiwan, and characterized by immunofluorescence analysis with monoclonal antibodies and by restriction fragment length polymorphism analysis of the 56-kilodalton (kDa) protein gene. The isolates were divided into two groups consisting of 1 and 9 strains which showed some relation to Gilliam and Karp type strains, respectively. However, all these isolates possessed characteristics distinct not only from those of known prototype strains including Gilliam and Karp but also from all isolates from Japan. These findings suggest the existence of a large number of immunotypic and genotypic variants among the strains of O. tsutsugamushi, and the distribution of distinguishable strains in each area to which this species is endemic.

[Spatial and temporally expressed proteins during Drosophila oogenesis as revealed by monoclonal antibodies]

By use of hybridoma technique, we have prepared 6 monoclonal antibodies. As shown by antibody labeling of whole mount ovary, four of them recognized, respectively, the antigens which were spatial-temporally expressed during oogenesis. The B 2 antigens appeared very early in the germarium and were expressed mainly by cystocyte and nurse cells. Later, they were all transported and localized in the posterior of oocyte, F 9 antigens followed and were also transported and localized in the posterior of oocyte in the stage 7-8. Then, E 8 antigens appeared and mainly localized on the membrane of oocyte in the stage 9-10. C 3 antigens were expressed much later, at about stage 14. They localized like two caps in the perivitelline fluid at both ends of matured egg. Such specific expression and distribution pattern of all these antigens suggest their possible roles during oogenesis.

Surgical treatment of complete acromioclavicular separations

A retrospective study of fifty-two patients (48 cases followed up), with Allman-Tossy grade III acromioclavicular separations, who were treated with coracoclavicular reconstruction by Mersilene prosthetic substitute (Mersilene tape with polyester suture, 5 mm wide, 30 cm, Ethicon), was carried out. The average follow up was 38 months, with the longest being 10 years, and the shortest being 8 months. The average age of the patients was 32 years, with a range from 20 to 62 years. Two groups were divided by age. Although the younger age group showed better results than the elder one in pain, range of motion and return to previous occupation or sports, the overall outcome was satisfactory in 41 of 48 (86%) followed patients. For the grade III acromioclavicular separation patients, surgical reconstruction with Mersilene looping provides a reliable result including use of the arm for sports or repetitive work.

Comparisons of geniposidic acid and geniposide on antitumor and radioprotection after sublethal irradiation

The antitumor effects of two iridoid compounds, geniposidic acid (GA) and geniposide (GP), were investigated in mice along with their possible effects on radioprotection after sublethal X-irradiation. Decreases in the growth of the implanted tumor by ascitic cells were a result of intraperitoneal administration of GA and GP at high concentrated levels. This result was achieved by exerting the levels of dosage in a dose-dependent manner. Except on the 12th day after treatment by the dosage of 500 mg/kg, reduced radiation effects of mice treated with the drugs in the 30 min preirradiated period by GA and GP on peripheral leukocytes were not observed significantly by the sublethal whole-body X-irradiation. And except on the 7th day after treatment, when these two compounds were administered i.p. to mice 30 min before 4 Gy irradiation, neither GA nor GP enhanced significantly the postirradiation responses of splenic blastogenesis by PHA. In addition, GA might be a more potent tumor growth inhibitor than GP when combined with the X-irradiation, though there was no significant synergetic effect on their combined antitumor activity. The preliminary results of GA and GP on hematological and blastogenic observations in this study suggested that they may very well, partially, play a role in an effective anticancer product with the ability to decrease undesirable radiation damage to the hematologic tissue after high dose irradiation.

The single positive T cells found in CD3-zeta/eta-/- mice overtly react with self-major histocompatibility complex molecules upon restoration of normal surface density of T cell receptor-CD3 complex

CD3-zeta/eta-deficient mice have small thymuses containing cells that show a profound reduction in the surface levels of T cell receptors and terminate their differentiation at the CD4+CD8+ stage. Rather unexpectedly, CD3- or very low single positive T cells accumulate over time in the spleen and lymph nodes of CD3-zeta/eta-deficient mice after a process dependent on MHC expression. Fusion of these peripheral T cells with a CD3-zeta-positive derivative of the BW5147 TCR-alpha-/beta- thymoma resulted in hybridomas that do express an heterogeneous set of T cell receptor alpha/beta dimers at their surface and at density comparable to those found in hybridomas derived from wild-type peripheral T cells. We have investigated the specificities of these T cell receptors using spleen cells from congenic and mutant mouse strains, and showed that the majority of them readily recognized self-MHC class I or class II molecules. These results demonstrate that by increasing the density and/or output of the T cell receptors expressed in peripheral T cells, one can confer them with the capacity to respond to normal density of self-MHC molecules.

Possible mechanism of exacerbating cataract formation in cataractous human lens capsules induced by systemic hypertension or glaucoma

To clarify the role of the lens capsule in cataract formation, changes in the protein conformational structure of immature cataractous lens capsules from patients with systemic hypertension or glaucoma have been investigated, as compared to normal lens capsules. The protein secondary structure and composition of these capsular samples were determined using Fourier transform infrared microspectroscopy with second-derivative, deconvolution and curve-fitting methods. We found that the composition of both random coil and beta-type (beta-sheet and beta-turn) structures in the immature cataractous human lens capsules was increasingly induced by systemic hypertension or glaucoma, but alpha-helix content clearly decreased, leading to the alteration of protein conformational structures in lens capsules. A possible pathway of cataract formation exacerbated by systemic hypertension or glaucoma is discussed. According to the results, we propose that systemic hypertension or glaucoma induce changes in the protein conformational structures of the lens capsule, then cause alteration of membrane transport and permeability for ions, and finally increase intraocular pressure, resulting in the exacerbation of cataract formation. The effect on the conformational structure of cataractous human lens capsules is more pronounced for systemic hypertension than for glaucoma. The present study implies that systemic hypertension or glaucoma can exacerbate cataract formation in senile patients by modifying the protein secondary structures in the lens capsule.

Functional trkB neurotrophin receptors are intrinsic components of the adult brain postsynaptic density

Neurotrophins have long been thought to act as target-derived factors that regulate the survival and differentiation of afferent neurons. Recently, brain-derived neurotrophic factor (BDNF) was shown to elicit rapid increases in synaptic activity of cultured hippocampal neurons by enhancing responsiveness to excitatory input. These findings suggest a postsynaptic localization of neurotrophin receptors. In this study, we examined the expression of trkB, a high-affinity receptor for BDNF, in the postsynaptic density (PSD), a proteinaceous specialization of the postsynaptic membrane. Western blot analyses with antibodies to trkB revealed localization to the PSD in adult rat cerebral cortex and hippocampus. Only the full-length, active form of trkB was detected in PSD samples. BDNF treatment of the adult cortical PSD resulted in a 5-fold increase in trkB autophosphorylation, supporting the contention that the PSD contains functional trkB. Truncated trkB, which does not contain the tyrosine kinase signaling domain, though present in membrane fractions, was undetectable in the PSD. The presence of trkB in the PSD is consistent with a role for neurotrophins in the regulation of synaptic activity via direct postsynaptic mechanisms.

Progressive changes in secondary conformation and composition of the senile cataractous human lens capsules

The lens capsules of senile cataractous patients were differentiated into three progressive grades of immature (I, II and III) and two progressive grades of mature (I' and II') groups using Fourier transform infrared (FT-IR) microspectroscopy with Fourier self-deconvolution and curve-fitting algorithms, according to the changes in IR peak position and its structural composition. The secondary conformation of both immature-II and mature-I' cataractous human lens capsules was found to change significantly when enhancing the beta-sheet structure but simultaneously decreasing the beta-turn structures, as compared with the composition of normal human and immature-I cataractous lens capsules. The increase in beta-sheet structural proportion might possibly be attributable to the age-related cataractogenesis. We also found that the IR peak at 1651 cm-1 assigned to a-helix shifted to 1647 cm-1 that corresponded to disordered structure, but the IR peak at 1662 cm-1 due to beta-turn structure disappeared and another new IR peak assigned to alpha-helix structure appeared at 1656 cm-1, for both immature-III and mature-II' cataractous lens capsules. It increased the compositions of beta-sheet and disorder structures and simultaneously decreased the triple helix and beta-turn structures, but maintained the same level in alpha-helix structure. This suggests that FT-IR microspectroscopy can act as a potential tool to exactly differentiate the maturity of senile cataractous human lens capsules according to the changes in IR peak position and compositions in amide I band.

The conformational properties of the antineoplastic ether lipid 1-thiohexadecyl-2-O-methyl-S-glycero-3-phosphocholine

Thio analogs of platelet activating factor (PAF) are of great interest because they exhibit antineoplastic properties both in vitro and in vivo. In contrast to most known anticancer agents, these lipids appear not to act through the synthesis and function of DNA and, therefore, offer a new avenue of approaching cancer chemotherapy. We have examined the conformational properties of 1-thiohexadecyl-2-O-methyl-S-glycero-3-phosphocholine (ET-S-16-OCH3) in organic solvents and in micelles. The conformational analysis was based on a combination of 1D, 2D NMR spectroscopy and molecular graphics. 1H and 13C spin lattice relaxation time (T1) experiments were also performed to study the dynamic properties of this molecule. The picture emerging from these studies is as follows. The alkyl chain of ET-S-16-OCH3 is the most mobile part of the molecule both in CDCl3/CD3OD and in micelles and exists as a mixture of interconverting conformers including an extended all trans and several low energy conformers with one or more gauche segments. This creates a twisting of the chain and facilitates a spatial communication between the alkyl chain and the glycerol backbone as well as between the alkyl chain and the headgroup. The methylene groups of the thioglycerol backbone and the headgroup are the least mobile while the methine group of the thioglycerol backbone appears to have an intermediate mobility. The conformation of the thioether lipid in the two media may be of relevance during its interaction with its site of action, the cellular membrane. Such a conformation may also play an important role in determining the selectivity of this interaction with different cell membranes.

Prenatal diagnosis of asphyxiating thoracic dysplasia (Jeune syndrome)

Asphyxiating thoracic dysplasia (ATD), or Jeune syndrome, is an uncommon autosomal recessive skeletal disorder characterized by a small thorax, varying degrees of rhizomelic brachymelia, polydactyly, pelvic abnormalities, and renal anomalies. We describe prenatal sonographic examinations in the third trimester of a fetus with abnormal small thorax, short limbs, polyhydramnios, and absence of fetal respiratory movements. At 36 weeks gestation, the fetal biparietal diameter was 93 mm, compatible with 37 weeks; the long-bone lengths measured < 5th percentile; the thoracic circumference (TC) measured 230 mm (< 5th percentile); the abdominal circumference (AC) measured 286 mm (25th percentile), and the TC/AC ratio was 0.80 (lower limit of normal). Our case shows that, although a discrepancy between gestational age and TC is prominent, TC/AC ratio may reach lower limit of normal in cases of fetal ATD, when fetal growth is compromised.

Highly dispersive photonic band-gap prism

We propose the concept of a photonic band-gap (PBG) prism based on two-dimensional PBG structures and realize it in the millimeter-wave spectral regime. We recognize the highly nonlinear dispersion of PBG materials near Brillouin zone edges and utilize the dispersion to achieve strong prism action. Such a PBG prism is very compact if operated in the optical regime, ~20 mm in size for lambda ~ 700 nm, and can serve as a dispersive element for building ultracompact miniature spectrometers.

[Effect of microinjection of angiotensin II into area postrema on renal sodium excretion]

It has been known that area postrema (AP) possesses angiotensin II (A II) receptors and senses directly the change of blood A II level. The effect of microinjection of A II into the AP on renal sodium excretion was studied in the present investigation. Our experimental results show that microinjection of A II (2, 20 ng) increases GFR, RPF and UNaV (P < 0.05). These changes can be abolished by A II antagonist, saralatin and renal denervation (P < 0.05). However microinjection of A II (20 ng) into NTS produces no such changes. These results strongly suggest that the A II induced changes of renal hemodynamics and urine sodium excretion are mediated through AP.

[Effects of subtotal nephrectomy and high salt intake on atrial natriuretic peptide in the brains of rats]

In order to explore the role of brain atrial natriuretic peptide (ANP) in regulating water and electrolytes, the changes of the ANP content of various brain areas in the status of high salt intake and in 3/4 nephrectomy rats. In control group, a wide distribution of ANP was observed in different areas of the brain. The amount of daily water intake and urine were larger, and urine sodium concentration was lower in the 3/4 nephrectomy group than those in the control group (P < 0.05). In the ten nuclei we have studied, ANP content was not significantly different from that of the control (P > 0.05). In the high salt group, water intake, urine volume and urine sodium concentration were significantly higher than those in the control. In this group, brain ANP increased in the periventricular nuclues (PVN) and arcute nucleus (Arc) (P < 0.05). The results indicate that ANP in anteroventral region of the third ventricle (AV3V) might play important role in the regulation of water and electolytes.

Synthesis and structure-DNA binding relationship analysis of DNA triple-helix specific intercalators

4-[N-(Aminoalkyl)amino]-2-arylquinolines with conformational freedom around positions 2 and 4 of the quinoline stabilize strongly poly(dT.dA.dT) (triplex DNA) and bind weakly to poly-(dA.dT) (duplex DNA). Basicity of N1 of the quinoline parallels the interaction strength of these compounds with the triple-helical DNA structure suggesting that N1 of the quinoline is protonated in the complex with the DNA triplex. The experimental results support the interaction model suggested previously.

Effects of compressive loading on articular cartilage repair of knee joint in rats

Effects of compressive loading on articular cartilage repair was studied. Thirty adolescent Long-Evans rats were used as experiment animals. A full-thickness defect of cartilage was created by drilling with a k-wire, 1.2 mm in diameter, into the weight bearing area of medial femoral condyle of each of bilateral knee joints. Free movement was permitted postoperatively. One leg of each rat received normal weight bearing on knee joint as experiment leg. The contralateral leg was used as the control. The control legs were paw resected to avoid weight bearing on joint cartilages but this did not interfere with the motion of knee joints. The articular cartilage repair was estimated by macroscopic examination and microscopic examination 6 weeks after surgery. Scoring systems were used to evaluate the quantity of repaired tissue in macroscopic examination and the quality of repaired tissue in microscopic examination. The differences of articular cartilage repair affected by compressive loading was analyzed statistically by paired t-test. We concluded that the effects of compressive loading on cartilage repair was to accelerate the metaplasia of repair tissue into hyaline cartilage but not to increase the quantity of repaired tissue.

Vibration measurement by the time-averaged electronic speckle pattern interferometry methods

Three different image-processing methods based on the time-averaged technique were compared by the electronic speckle pattern interferometry (ESPI) technique for vibration measurement. The three methods are the video-signal-addition method, the video-signal-subtraction method, and the amplitude-fluctuation method. Also, errors introduced by using the zero-order Bessel function directly into the analysis of the fringe pattern were investigated. The video-signal-addition method has been the most generally used ESPI technique for vibration measurement. However, without additional image and/or signal-processing procedures, the fringe pattern obtained directly by the video-signal-addition method is rather difficult to observe. The reason for poor visibility of the experimentally obtained fringe pattern with this method is explained. To increase the fringe pattern's visibility without additional image and/or signal processes, we tried two video-signal-subtraction methods. One of the two methods is the video-signal-subtraction method that has normally been used in the static applications. The other method, called the amplitude-fluctuation method, and its associated theory are reported here.

Covalent assembly of a soluble T cell receptor-peptide-major histocompatibility class I complex

We used stepwise photochemical cross-linking for specifically assembling soluble and covalent complexes made of a T-cell antigen receptor (TCR) and a class I molecule of the major histocompatibility complex (MHC) bound to an antigenic peptide. For that purpose, we have produced in myeloma cells a single-chain Fv construct of a TCR specific for a photoreactive H-2Kd-peptide complex. Photochemical cross-linking of this TCR single-chain Fv with a soluble form of the photoreactive H-2Kd-peptide ligand resulted in the formation of a ternary covalent complex. We have characterized the soluble ternary complex and showed that it reacted with antibodies specific for epitopes located either on the native TCR or on the Kd molecules. By preventing the fast dissociation kinetics observed with most T cell receptors, this approach provides a means of preparing soluble TCR-peptide-MHC complexes on large-scale levels.

[Pulmonary and paradoxical embolism after total knee replacement--a case report]

Pneumatic tourniquet and hone cement are often applied in orthopaedic surgery. In lower limb surgery, deep vein thrombosis may occur after release of tourniquet, causing embolism of lungs and vital organs. Paradoxical embolism may develop if the patients present extracardiac or intracardiac right to left shunt, such as atrial septum defect, etc. A 60-year-old female patient suffered from osteoarthritis of both knees was admitted for total knee replacement (TKR). Pneumatic tourniquet was inflated on the operated leg for the orthopaedic surgery which lasted for 2h. Dyspnea, sinus tachycardia and abdominal pain were noted after TKR. Blood gases analysis showed arterial hypoxemia and respiratory alkalosis. Chest X-ray revealed diffused bilateral pulmonary infiltration, pulmonary trunk engorgement, and decreased lung markings. Two days after TKR under the impression of peritonitis, she received exploratory laparotomy in which ischemic bowel and gall bladder were found. Pulmonary and paradoxical embolism were diagnosed, both of which were the well-known complications of TKR with tourniquet and bone cement application. The patient finally succumbed because of multiple organ failures.

Permeation behavior of salbutamol sulfate through hydrophilic and hydrophobic membranes embedded by thermo-responsive cholesteryl oleyl carbonate

PURPOSE

To investigate the suitability of hydrophilic or hydrophobic membranes for use as potential thermo-responsive drug delivery system.

METHODS

Liquid crystal was embedded in membranes using vacuum filtration method to control the penetration rate of salbutamol sulfate. Cholesteryl oleyl carbonate (COC) with smectic-cholesteric phase transition temperature near 18 degrees C was used as a model liquid crystal.

RESULTS

It indicates only hydrophilic salbutamol sulfate can penetrate through the hydrophilic membranes embedded with or without COC, in which the permeation is mainly governed by the adsorption of COC. However, the hydrophilic drug do not pass through the hydrophobic membranes even if not embedded with COC. The void volume of the membrane also influences the penetration of salbutamol sulfate. The higher thermo-response efficacy of the COC-embedded membranes can be explained not only by less permeability through matrix part of the membrane but also by higher thermal motion of the COC molecules due to above the phase transition temperature.

CONCLUSIONS

A COC-embedded membrane with rate-controlled and thermo-responsive function is easily prepared by vacuum filtration method. High reversibly thermo-responsive function can be achieved by choosing membrane and COC concentration properly.

Possible changes in secondary structure and composition of human lens capsules in hereditary congenital cataract

BACKGROUND

Scanty information is available on the changes in conformational structure and composition of human lens capsule in cases of hereditary congenital cataract. The purpose of this study was to use Fourier-transformed infrared (FT-IR) spectroscopy to determine the secondary structure and composition of hereditary cataractous human lens capsule, as compared with normal human lens capsule.

METHODS

FT-IR spectroscopy with the Fourier self-deconvolution and curve-fitting program was performed, and second-derivative analysis was used to verify the peak positions and assignments of the IR spectra.

RESULTS

The curve-fit FT-IR spectra revealed that the content of hydroxylysine and arginine were clearly higher in the lens capsule of the hereditary congenital patient, but the content of aspartic acid significantly lower, than in normal human lens capsules. The secondary conformational changes in alpha-helix, triple helix and random coil structures were important findings in the lens capsule of a hereditary cataractous patient.

CONCLUSION

Possible alterations in secondary structures and compositions of lens capsule are observed in the hereditary congenital cataractous patient by using FT-IR spectroscopy with curve-fitting and second-derivative analysis.

Malignant familial hypertrophic cardiomyopathy in a family with a 453Arg-->Cys mutation in the beta-myosin heavy chain gene: coexistence of sudden death and end-stage heart failure

Recent genotype-phenotype correlation studies in familial hypertrophic cardiomyopathy (FHC) have revealed that some mutations in the beta- myosin heavy chain (BMHC) gene may be associated with a high incidence of sudden death and a poor prognosis. Coexistence of sudden death and end-stage heart failure in several families with FHC has recently being reported; however, the genetic basis of such families has not been clearly demonstrated. A three-generation Chinese familial hypertrophic cardiomyopathy (FHC) family (family HLI) with two cases of end-stage heart failure and three cases of sudden death was analyzed. The average age of death in the affected members in this family was 34 years old. Genetic linkage analysis using polymorphisms in the (alpha- and beta-myosin heavy chain genes revealed that FHC in this family is significantly linked to the BMHC gene without recombinations. Single-strand conformation polymorphism analysis of exons 8, 9 and 13 to 23 in the BMHC gene showed a polymorphic band on exon 14 that is in complete linkage with the disease status in this family. DNA sequencing analysis in the affected members revealed an 453Arg-->Cys mutation in the BMHC gene. To our knowledge this is the first reported mutation of FHC in Chinese. Our data suggest that the 453Arg-->Cys mutation is associated with a malignant clinical course in FHC due not only to sudden death but also to end-stage heart failure.

Microscopic FT-IR/DSC system used to simultaneously investigate the conversion process of protein structure in porcine stratum corneum after pretreatment with skin penetration enhancers

A newly developed microscopic Fourier transform infrared (FT-IR) spectrometry combined with differential scanning calorimetry (DSC) was used to investigate the thermal response and IR spectral changes of protein structure in porcine stratum corneum (SC) after pretreatment with the skin penetration enhancers propylene glycol (PG), azone/PG, oleic acid (OA)/PG, vitamin C, and vitamin C+ OA/PG. The amide I and II bands of protein were used as probe to determine the structural transformation of protein with temperature. A reheating process was also performed. Dual effects of enhancer and temperature on the protein conformational changes of porcine SC were studied. The results indicate that the new FT-IR/DSC system can continuously determine the thermoresponsive conversion process from alpha-helix to beta-sheet in keratin structure of porcine SC pretreated with different enhancers. The thermally induced keratin conversion in protein structure of porcine SC, independent of pretreatment with skin penetration enhancers, was irreversible. The process of conformational transition in protein was found to be partially from alpha-helix to random coil structure or partially from alpha-helix to beta-sheet structure during heating. The kinetics of this conversion between first-heating and second-heating processes were significantly different; the process of conversion for all first-heated porcine SC samples during second-heating process were slower than that of porcine SC samples during first-heating process. Moreover, it was also found that the skin penetration enhancers, when present during the heating process, were able to synergistically and promotively alter the keratin conversion in protein structure of porcine SC, with the PG, OA/PG and azone/PG enhancers being the most effective.

Mapping the locus for familial hypertrophic cardiomyopathy to chromosome 11 in a family with a case of apical hypertrophic cardiomyopathy of the Japanese type

To identify the disease locus of familial hypertrophic cardiomyopathy (FHC) in a Chinese family, a genetic linkage study was performed using polymorphisms from various chromosomal regions. This family has eight affected members, including a case with typical features of apical hypertrophic cardiomyopathy of the Japanese type. The results revealed significant evidence of linkage of polymorphisms on chromosome 11p13-q13 and FHC in this family with a maximal lod score of 3.38 at theta = 0.00. Our data suggest that the locus responsible for FHC in this family maps to chromosome 11 and that the molecular basis of FHC in the case of apical hypertrophic cardiomyopathy of the Japanese type might be similar to that of other affected members in the same family. Further studies are needed to elucidate the whole spectrum of the genetic basis of apical hypertrophic cardiomyopathy of the Japanese type.

Cell cycle-regulated association of E2F1 and Sp1 is related to their functional interaction

Because of the large number of growth-regulated genes containing binding sites for the transcription factors Sp1 and E2F and the reported ability of E2F to mediate cell cycle (growth) regulation, we studied interactions between E2F1 and Sp1. In transient transfection assays using Drosophila melanogaster SL2 cells, transfection with both Sp1 and E2F1 expression vectors resulted in greater than 85-fold activation of transcription from a hamster dihydrofolate reductase reporter construct, whereas cotransfection with either the Sp1 or E2F1 expression vector resulted in 30- or <2-fold activation, respectively. Therefore, these transcription factors act synergistically in activation of dihydrofolate reductase transcription. Transient transfection studies demonstrated that E2F1 could superactivate Sp1-dependent transcription in a promoter containing only Sp1 sites and that Sp1 could superactivate transcription of promoters through E2F sites, further demonstrating that these physically associated in Drosophila cells transfected with Sp1 and E2F1 expression vectors and in human cells, with maximal interaction detected in mid- to late G1. Additionally, E2F1 and Sp1 interact in vitro through specific domains of each protein, and the physical interaction and functional synergism appear to require the same regions. Taken together, these data demonstrate that E2F1 and Sp1 both functionally and physically interact; therefore this interaction, Sp1 and E2F1 may regulate transcription of genes containing binding sites for either or both factors.