Do screws and screw holes affect osteolysis in cementless cups using highly crosslinked polyethylene? A 7 to 10-year follow-up case-control study

BACKGROUND

The use of screws and the presence of screw holes may cause acetabular osteolysis and implant loosening in cementless total hip arthroplasty (THA) using conventional polyethylene. In contrast, this issue is not fully understood using highly crosslinked polyethylene (HXLPE), particularly in large comparative study. Therefore, we performed a case-control study to assess the influence of screw usage and screw holes on: (1) implant fixation and osteolysis and (2) polyethylene steady-state wear rate, using cases with HXLPE liners followed up for 7-10 years postoperatively.

HYPOTHESIS

The screw usage and screw holes adversely affect the implant fixation and incidence of wear-related osteolysis in THA with HXLPE.

PATIENTS AND METHODS

We reviewed 209 primary cementless THAs performed with 26-mm cobalt-chromium heads on HXLPE liners. To compare the effects of the use of screws and the presence of screw holes, the following groups were established: (1) with-screw (n=140); (2) without-screw (n=69); (3) no-hole (n=27) and (4) group in which a cup with screw holes, but no screw was used (n=42). Two adjunct groups (no-hole cups excluded) were established to compare the differences in the two types of HXLPE: (5) remelted group (n=100) and (6) annealed group (n=82). Implant stability and osteolysis were evaluated by plain radiography and computed tomography. The wear rate from 1 year to the final evaluation was measured using plain X-rays and PolyWare Digital software.

RESULTS

All cups and stems achieved bony fixation. On CT-scan, no acetabular osteolysis was found, but there were 3 cases with a small area of femoral osteolysis. The mean steady-state wear rate of each group was (1) 0.031±0.022, (2) 0.033±0.035, (3) 0.031±0.024, (4) 0.029±0.018, (5) 0.030±0.018 and (6) 0.034±0.023mm/year, respectively. A comparison of the effects of screw usage or screw holes found no significant between-group differences in the implant stability, prevalence of osteolysis [no acetabular osteolysis and 3/209 at femoral side (1.4%)] and steady-state wear rate.

DISCUSSION

This study suggests that there are no adverse effects on the results of THA with HXLPE from the use of cups with screw holes and the use of screws for cup fixation.

LEVEL OF EVIDENCE

Level III retrospective case-control study.

Comparison of wear rate and osteolysis between second-generation annealed and first-generation remelted highly cross-linked polyethylene in total hip arthroplasty. A case control study at a minimum of five years

BACKGROUND

There is no previous report that directly compared wear resistance of second-generation annealed highly cross-linked polyethylene with that of first-generation remelted highly cross-linked polyethylene. We therefore performed a retrospective study at a minimum of 5-year follow-up comparing second-generation annealed and first-generation remelted highly cross-linked polyethylene in order to: (1) assess wear rates and (2) compare the incidence of osteolysis between, (3) identify the frequency of complication related to the two types of highly cross-linked polyethylene.

HYPOTHESIS

There is a difference in the linear wear rate and the incidence of osteolysis between the two types of highly cross-linked polyethylene in total hip arthroplasty.

MATERIALS AND METHODS

In a single centre study, we reviewed 123 primary cementless total hip arthroplasties between 2010 and 2011 that were performed with 32mm alumina ceramic on second-generation annealed (X3) or first-generation remelted (Longevity) highly cross-linked polyethylene liner. There was no specific reason for the choice of the type of highly cross-linked polyethylene. There were no significant differences between the two groups in respect of gender, diagnosis, body mass index, pre- and post-operative functional and activity score, cup size, and cup orientation except the younger age in the X3 group. The mean wear rate and the incidence of osteolysis were evaluated at the latest follow-up.

RESULTS

One hundred nine cases followed over 5 years post-operatively (88.6% in all consecutive cases) were evaluated. X3 and Longevity were used in 54 and 55 cases, respectively. The mean follow-up was 5.3 years in both groups. The mean linear wear rate of X3 and Longevity group was 0.045±0.023mm/year and 0.076±0.031mm/year, respectively (P<0.001). No osteolysis was found on plain X-rays in both groups and no specific complication was related to these highly cross-linked components.

DISCUSSION

Excellent wear resistance of both types of highly cross-linked polyethylene liner was revealed in our study. The difference of wear rate between two materials should be monitored in a longer follow-up.

LEVEL OF EVIDENCE

Level III retrospective case control study.

Effect of cellulase supplementation in low-crude protein diets on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in broilers

1. Two experiments were conducted to investigate the effect of dietary enzyme supplementation of a low-protein diet on performance, nitrogen excretion, fat deposition, hepatic lipogenic and lipolytic enzyme activity in 7-21- (Experiment 1) and 21-42-d-old (Experiment 2) male broiler chicks. 2. Chicks were given diets containing 210 g (Experiment 1) or 170 g (Experiment 2) crude protein (CP)/kg (Control), amino acid-fortified diets 190 g (Experiment 1) and 150 g (Experiment 2) CP/kg (Low-protein), and a low-protein diet supplemented with 1000 U/kg of cellulase. 3. In Experiment 1, growth performance and abdominal fat deposition were not affected by dietary treatments, and birds given low-protein diets excreted less nitrogen. The activities of hepatic lipogenic and lipolytic enzymes were not different among the three dietary groups. 4. In Experiment 2, the dietary treatment did not affect growth performance or abdominal fat weight. Nitrogen excretion was significantly lower in chicks given the 150 g/kg CP diet than those on the 170 g/kg CP diet; however, nitrogen retention was no different among the treatments. Dietary CP and enzyme supplementation did not significantly affect hepatic enzyme activities. 5. These results suggest that CP content in the broiler diet can be reduced by 20 g/kg without lowering performance by the supplementation of crystalline amino acids, and can reduce nitrogen excretion by about 25%. Cellulase supplementation of a low-CP diet slightly lowered abdominal fat deposition; however, it did not significantly affect hepatic lipogenic and lipolytic enzyme activity.

Consideration of physical condition in estimation of blood glucose via data mining

Many diabetics carry a portable-type blood glucose monitor and collect their own blood to examine their blood glucose levels daily (self monitoring of blood glucose, SMBG). The use of a physical condition variable was suggested in order to estimate the blood glucose level for diabetics. Four sets of data, including FBG, food intake, metabolic rate and physical condition, were collected from four Type 1 diabetics over a five-month period. Using these data, an increasing or decreasing tendency for FBG for the next day was estimated using the data mining method. The results revealed that the estimation accuracy was improved when a physical condition variable was used. An average correspondence rate of 81 % was observed, with a maximum of 90 %. These results indicated that the data mining method could be effective in the estimation of blood glucose levels.

Interferon-gamma is causatively involved in experimental inflammatory bowel disease in mice

Cytokines may be crucially involved in the pathogenesis of inflammatory bowel diseases (IBD), but it remains controversial whether interferon (IFN)-gamma, a typical proinflammatory cytokine, is an essential mediator to cause the disorders. In the present study, IFN-gamma(-/-) and wild-type (WT) C57BL/6 mice were fed 2.5% dextran sodium sulphate (DSS) in drinking water for 7 days, in order to investigate DSS-induced intestinal inflammation. The DSS-treated WT mice exhibited a robust production of IFN-gamma in the gut, a remarkable loss of body weight, as well as high rate of mortality (60%). In striking contrast, IFN-gamma deficient mice did not develop DSS-induced colitis, as indicated by the maintenance of body weight and survival rate of 100%. Severe intestinal inflammation was demonstrated exclusively in WT animals in terms of the shortening of the bowel as well as the elevation of the disease activity index, myeloperoxidase (MPO) activity and serum haptoglobin level. Histological study of DSS-treated WT intestine revealed disruption of mucosal epithelium and massive infiltration of inflammatory cells, while the organ from IFN-gamma(-/-) mice remained virtually normal in appearance. Enzyme-linked immunosorbent assay (ELISA) analyses indicated abundant production of three chemokines, i.e. monokine induced by interferon-gamma (MIG), interferon-inducible protein 10 (IP-10) and monocyte chemoattractant protein-1 (MCP-1), in the DSS-irritated intestine of WT but not of IFN-gamma(-/-) mice. The present results demonstrate clearly that IFN-gamma plays indispensable roles in the initiation of DSS colitis, and some chemokines are produced in an IFN-gamma-dependent fashion.

Evidence of local antibody response against Alloiococcus otitidis in the middle ear cavity of children with otitis media

Alloiococcus otitidis is a recently discovered bacterium frequently associated with otitis media. However, no study is available as to whether A. otitidis has a pathogenic role and induces local immune response in the middle ear as a true pathogen. Whole bacterial sonicate of A. otitidis was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and transferred to a nitrocellulose membrane. Then, Western blot analysis was performed with supernatant of the middle ear effusions from children with A. otitidis-positive otitis media. SDS-PAGE of the bacterial sonicate showed several protein bands, designated A1-A11. Western blot analysis revealed the presence of IgG, secretory IgA, IgG2, and IgM against A. otitidis in the middle ear effusions. Absorption of the specimens with sonicates of other major middle ear pathogens did not alter the reactivity of antibodies against the alloiococcal antigens. The results suggest that specific local immune response against A. otitidis is induced during middle ear infection of the organism as a true pathogen. A5, A6 or A11 is expected to be a main antigenic determinant. This is the first report to show evidence of local antibody response against A. otitidis and to disclose antigenic components of A. otitidis.

High incidence of Alloiococcus otitidis in children with otitis media, despite treatment with antibiotics

Acute otitis media (AOM) and otitis media with effusion (OME) are common diseases in childhood. Alloiococcus otitidis is a newly recognized species of gram-positive bacterium which was recently discovered as a pathogen associated with OME. Although some studies show that A. otitidis is frequently detected in children with OME, no study is available concerning the clinical efficiency of antibiotics against this organism. The prevalence of A. otitidis in 116 middle ear effusion specimens from 36 AOM and 52 OME patients was examined by culture and PCR. In addition, the prevalence of the bacterium was retrospectively investigated in relation to antibiotic use. A. otitidis was detected in 20 (50%) AOM and 47 (61%) OME specimens. The organism was the most frequent bacterium in AOM as well as in OME and was highly detected even in patients who had been treated with antibiotics, such as beta-lactams or erythromycin. The incidence of A. otitidis in our study was higher than that in Western countries, and our results suggest that drug-resistant strains of A. otitidis may be frequently spread in Japanese children. Our study suggests that antibiotics such as beta-lactams or erythromycin may not be sufficiently effective to eliminate this organism. Further investigation is expected to reveal the clinical role of the organism in otitis media.

High frequency of Alloiococcus otitidis in the nasopharynx and in the middle ear cavity of otitis-prone children

OBJECTIVE

Colonization of middle ear pathogens is facilitated in the nasopharynx of otitis-prone children, and is associated with the development of otitis media. Recently, a new species of bacterium, Alloiococcus otitidis, is considered as one of the major middle ear pathogens. However, as far as we know, no study has been reported concerning the prevalence of A. otitidis in the nasopharynx of otitis-prone children. And, no study has been conducted on the association of A. otitidis in the nasopharynx with otitis media.

METHODS

The frequency of A. otitidis in 83 middle ear effusions (MEE) and 56 nasopharyngeal swab (NPS) specimens from 56 children with otitis media was investigated by culture and polymerase chain reaction (PCR).

RESULTS

A. otitidis was detected in 24 (28.9%) of MEE and in 6 (10.7%) of NPS specimens. When the frequency was investigated in relation to proneness to otitis media, A. otitidis was detected in 16 (64%) of 25 MEE and in 5 (29.4%) of 17 NPS specimens from otitis-prone children, whereas it was detected in 8 (13.8%) of 58 MEE and in 1 (2.6%) of 39 NPS specimens from non-otitis-prone children. The frequency of A. otitidis in both NPS and MEE specimens was significantly higher in otitis-prone than in non-otitis-prone children.

CONCLUSIONS

Our results suggest that colonization of A. otitidis is facilitated in the nasopharynx of otitis-prone children. And, nasopharyngeal colonization of A. otitidis may be associated with the frequency of otitis media.

Severe hypertension associated with multiple intrarenal microaneurysms in a patient with systemic lupus erythematosus and antiphospholipid antibodies

Abstract  A 26-year-old Japanese woman with systemic lupus erythematosus (SLE) developed severe hyperten-sion and an increased active renin concentration (ARC), ischemic colitis, and splenic infarction. She had antiphospholipid antibodies (APA), multiple intrarenal microaneurysms, and multiple stenoses of the mesenteric arteries. Combination therapy with antihypertensive agents, aspirin, warfarin, and corticosteroids (30 mg daily) controlled her abdominal symptoms and hypertension. Multiple intrarenal microaneurysms in SLE with APA may be the cause of severe hypertension and elevated serum ARC.

Differential regulation of porcine hepatic IGF-I mRNA expression and plasma IGF-I concentration by a low lysine diet

The influence of dietary lysine on hepatic insulin-like growth factor-I (IGF-I) gene expression and plasma IGF-I level was investigated. Two male 6-wk-old pigs from each of six litters were used. Each littermate was assigned to one of two diets, control or low lysine (LL), that were isoenergetic and similar in protein content and provided 14.3 MJ digestible energy/kg for both diets, 185 g protein/kg for the control diet and 180 g protein/kg for the LL diet. The control diet contained all essential amino acids in the recommended amounts, including 11.5 g lysine/kg. The LL diet was similar but contained only 7 g lysine/kg. Pigs were pair-fed these diets for 3 wk. Growth rates and feed efficiencies of pigs fed the LL diet were significantly lower than those of pigs fed the control diet (P < 0.01). Plasma IGF-I levels in pigs fed the LL diet were 52% lower than in those fed the control diet (P < 0.01), and the LL group also had lower plasma IGF-binding protein-3 (IGFBP3) levels (P < 0.05). Despite the strikingly lower plasma IGF-I in pigs fed the LL diet, hepatic IGF-I mRNA abundance did not differ between the two treatment groups. We conclude that the reduction in plasma IGF-I caused by reduced dietary lysine may have been due in part to suppression of post-transcriptional events in IGF-I expression. The lower plasma IGFBP3 in pigs fed the LL diet suggests that increased clearance rates of circulating IGF-I may have been involved in this response.

Inhibitory effect of a presenilin 1 mutation on the Wnt signalling pathway by enhancement of β-catenin phosphorylation

Mutations in the presenilin 1 (PS1) gene are the most common genetic factor underlying the development of early onset familial Alzheimer's disease (FAD). Accumulating evidence has shown that FAD-linked mutations of PS1 enhance the generation of amyloid-beta (1-42) protein. Recently, beta-catenin has been shown to interact with PS1. beta-catenin is essential for the Wnt signalling pathway. However, the biological significance of the interaction between beta-catenin and PS1 in this signalling pathway remains to be clarified. In this study, we investigated the effect of FAD-linked PS1 (M146L) mutation in the Wnt signalling pathway using the conditioned medium containing Wnt-3A. The expression of mutated PS1 inhibited the Wnt-3A-induced accumulation of beta-catenin. Chase analysis of beta-catenin in Wnt-3A-stimulated cells following cycloheximide treatment revealed that PS1 mutation enhanced the generation of the higher molecular mass form of beta-catenin, most likely, ubiquitinated beta-catenin. In addition, the expression of mutated PS1 elevated the level of phosphorylated beta-catenin, which is targeted to the ubiquitin/proteasome pathway. Thus, it appears that PS1 (M146L) mutation down-regulates the Wnt-3A-induced accumulation of beta-catenin due to an increase in the level of phosphorylated beta-catenin.

T-helper (Th)1/Th2 imbalance in patients with previously untreated B-cell diffuse large cell lymphoma

T-helper (Th)1/Th2 imbalance has been observed in a variety of pathological conditions, including malignant diseases. We evaluated the Th1/Th2 balance in peripheral blood Th cells by means of intracellular cytokine analysis in 19 patients with previously untreated B-cell diffuse large cell lymphoma (DLCL) and in 18 patients with B-cell DLCL who had achieved complete remission (CR) after chemotherapy. The mean percentage of Th2 in CD4 cells in patients with DLCL (5.00 +/- 2.20) and that of Th1 in CD4+ cells in patients in CR (32.42 +/- 11.30) were significantly increased in comparison with those in healthy volunteers, respectively (Th1; 23.02 +/- 9.45, Th2; 3.25 +/- 0.90; P<0.01). The mean ratio of Th1/Th2 was significantly lower in patients with DLCL (4.74 +/- 0.52) than in patients in CR (9.31 +/- 1.06; P<0.01) and in healthy volunteers (7.25 +/- 0.65; P<0.01). We conclude that the Th1/Th2 balance was polarized to Th2 in untreated DLCL patients and to Th1 in patients in CR, which suggests that a Th1/Th2 imbalance could play a role in lymphomagenesis and durable remission.

Multifocal electroretinograms in patients with branch retinal artery occlusion

PURPOSE

We recorded multifocal electroretinograms (M-ERG) in patients with branch retinal artery occlusion (BRAO) and compared the waveforms in the area of retinal artery occlusion with those in the normal area, to evaluate the influence of the damage to the inner retina shown by M-ERG responses.

METHODS

Three patients who had normal visual acuity and visual field loss of more than one quadrant due to BRAO were examined. The central 50 degrees of ocular fundus was stimulated through dilated pupils by an array of 103 hexagonal elements for 4 minutes. The waveforms of the first order and second order kernel responses of M-ERG in the area of the retinal artery occlusion were compared with those of the vertically symmetrical, normally perfused area of the same eye.

RESULTS

The amplitude of the averaged tracing decreased in the first negative wave (N1), first positive wave (P1), and second negative wave (N2) in the first order kernel responses in the area of retinal artery occlusion in comparison with the normally perfused area. Furthermore, prolongation of latency was noted for N1, P1, and N2 in the same area. Second order kernel responses were not detected in the area of the retinal artery occlusion.

CONCLUSIONS

The damage to the inner retina affected parts of N1, P1, and N2 of the first order kernel responses, with N2 being the most seriously affected. Furthermore, second order kernel responses clearly reflected the condition of the inner retina.

p73beta, a variant of p73, enhances Wnt/beta-catenin signaling in Saos-2 cells

The Wnt/beta-catenin pathway and p53 are very common targets for genetic alterations in colorectal cancer, and relationships between them have been reported. Here, we describe the relation between Wnt/beta-catenin signaling and the p53-related gene p73. p73, but not p53, activated a promoter containing the Tcf-binding sequence in Saos-2 cells, and the degree of activation was positively correlated with that on a p53-responsive promoter. Moreover, p73beta enhanced Wnt/beta-catenin signaling synergistically with Wnt-3a or exogenously expressed beta-catenin, unlike p53, and the enhancement was not caused by the accumulation of beta-catenin. These results show that the effects of p73 on Wnt/beta-catenin signaling differ from those of p53.

A case of superior oblique myokymia observed by an image-analysis system

Superior oblique myokymia is a microtremor of the eye that causes monocular torsional oscillopsia. A modified Harada-Ito procedure was used to treat a case of the disease in a 20-year-old woman. The authors used video-image analysis pre- and postoperatively to evaluate the effect of the surgery on abnormal torsional eye movements. This analysis revealed that before surgery, the abnormal torsional movement had a very regular cycle (duration of attack, 8.0 +/- 0.5 s; time interval between attacks, 18.7 +/- 3.2 s; n = 9). After the surgery, amplitude of the abnormal torsional eye movement was reduced, and the oscillopsia had subjectively improved, although the movement cycle remained unchanged. The authors' video-image analysis, which used iris striation, proved to be a useful method for clinical measurement of torsional eye movements.

Isolated cardiac metastasis from sacral chordoma

A 64-year-old woman presented with right heart failure caused by a cardiac tumor centered in the free wall of the right ventricle, accompanied by pericardial effusion. A match between the biopsy specimen and tissue removed 4 years earlier resulted in the diagnosis of a cardiac metastasis from a chordoma. Immunohistochemical staining was also useful in establishing the diagnosis. To alleviate the right ventricular outflow obstruction, a palliative operation was planned, resecting the tumor and performing a right ventriculoplasty, which was cancelled due to the extent of infiltration of the tumor, and instead a right atrium to pulmonary artery shunt was attempted using a vascular prosthesis, only to fail due to an inability to maintain blood flow through the prosthesis. Presently there are no definitive treatment options available, and some palliative chemotherapy is being performed. Single cardiac metastases from a chordoma are extremely rare.

[Quantitative evaluation of nystagmus by an image-analysis system]

PURPOSE

We attempted to apply a newly developed image-analysis system for measurement and analysis of nystagmus.

METHOD

Eye movements were recorded by digital video through a head-mounted charge coupled device (CCD) camera. The recorded movie was converted into black and white in order to detect the area of the pupil. Horizontal and vertical eye positions were determined by calculating the centroid of the pupil. Torsional angle was calculated using the iris striate pattern around the pupillary margin.

RESULTS

The parameters (amplitude, cycle, etc.) of nystagmus were calculated easily by the new image-analysis system from the recorded images. As examples, the foveation period was measured accurately in a case of jerky-type congenital nystagmus. Very regular cycles of intorsional attack period were revealed in a case of superior oblique myokymia. A case of cork-screw-like nystagmus showed a characteristic combination of large and small cycles unassociated with torsion.

CONCLUSION

This image-analysis system was useful for quantitative analysis of nystagmus, and especially for measurement of torsion. Detailed waveforms and specific rhythms of nystagmus, which could not be recognized by observation, were demonstrated by this system.

Induction of melanocyte-specific microphthalmia-associated transcription factor by Wnt-3a

Microphthalmia-associated transcription factor (Mitf) plays a critical role in the development of neural crest-derived melanocytes. Here, we show that exogenously added Wnt-3a protein, an intercellular signaling molecule, up-regulates the expression of endogenous melanocyte-specific Mitf (Mitf-M) mRNA in cultured melanocytes. The melanocyte-specific promoter of the human MITF gene (MITF-M promoter) contains a functional LEF-1-binding site, which is bound in vitro by LEF-1 and confers the preferential expression on a reporter gene in melanocytes and melanoma cells, as judged by the transient transfection assays. Moreover, the LEF-1-binding site is required for the transactivation of a reporter gene by LEF-1, beta-catenin, or their combination. Exogenously added Wnt-3a protein also transactivates the MITF-M promoter via the LEF-1-binding site; this activation was abolished when a dominant-negative form of LEF-1 was coexpressed. These results suggest that Wnt-3a signaling recruits beta-catenin and LEF-1 to the LEF-1-binding site of the MITF-M promoter. Therefore, the present study identifies Mitf-M/MITF-M as a direct target of Wnt signaling.

Waveform changes of the first-order multifocal electroretinogram in patients with glaucoma

PURPOSE

To investigate the relationship between the components of the first-order multifocal electroretinogram (M-ERG) and glaucomatous visual field loss.

METHODS

Twenty-six eyes of 14 patients with primary open-angle glaucoma (POAG) were evaluated with the M-ERG techniques. Twenty-six eyes of 26 normal subjects also were tested as control subjects. To record the M-ERG, a stimulus matrix of 103 scaled hexagonal elements was displayed on a monitor driven at a 75-Hz frame rate according to a binary m-sequence. The M-ERG responses were averaged in each quadrant of the stimulus field and the peak-to-trough amplitudes and peak implicit times of the first trough (N1), the first peak (P1), and the second trough (N2) of the M-ERG were compared with the mean sensitivity values (dB) of the corresponding quadrant of the Humphrey static perimetric field.

RESULTS

The changes in the peak latencies of P1 and N2 in the POAG group were small but significant compared with those in the normal group (P < 0.01). However, no significant differences in the amplitudes of (P1-N1) and (P1-N2) between the two groups were found. Significant negative correlations between the peak implicit times of N1, P1, and N2 and the mean sensitivity values (dB) of static perimetry were observed. The correlation coefficients were -0.20 (P < 0.05) for the N1, -0.41 (P < 0.001) for the P1, and -0.59 (P < 0.001) for the N2. No significant correlations were observed between the amplitudes (P1-N1 and P1-N2) and the mean sensitivity values.

CONCLUSIONS

The present study findings suggest that the peak implicit times, but not the amplitudes, of the M-ERG increase as the glaucomatous visual field deteriorates. The amplitudes of the M-ERG did not decrease as the glaucomatous optic nerve dysfunction progressed.

Effects of localized lesions in the lateral suprasylvian cortex on convergence eye movement in cats

We evaluated the effects of electrolytic lesions in the extrastriate cortical area on the amplitudes and velocities of vergence eye movements in six alert cats that were trained to track a target moving in depth. Bilateral or unilateral lesions in the lateral suprasylvian (LS) cortex reduced the amplitudes and velocities of vergence eye movements, but the positive correlation between them was maintained. Furthermore, unilateral lesions changed the symmetry of eye movements. Movements of the left eye were decreased by lesions in the right LS cortex, resulting in asymmetric vergence eye movement with right eye predominance, and vice versa. These results support the hypothesis that the LS cortex plays an essential role in controlling vergence eye movement.

[Multifocal electroretinogram in central serous chorioretinopathy]

PURPOSE

To assess retinal function topographically in the affected eyes with central serous chorioretinopathy (CSC).

PARTICIPANTS AND METHOD

We recorded multifocal electroretimogram (mERG) in 5 patients with unilateral CSC, and analyzed the topographical properties in the central visual field (rings #1 + 2).

RESULTS

mERG amplitudes in the CSC eyes were significantly reduced compared with the fellow eyes, for P 1-N 1 (58.5 +/- 23.5%, p < 0.05) and for P 1-N 2 (47.5 +/- 15.0%, p < 0.05). mERG latencies in the CSC eyes were significantly increased compared with those in the fellow eyes, for N 1 (by 9.0 +/- 8.1%, p < 0.05) and for P 1 (by 8.4 +/- 7.0%, p < 0.05). mERGs in the CSC eyes gradually recovered in the follow-up period. However, the responses did not recover to normal value during follow-up, even when the subretinal fluid disappeared ophthalmoscopically.

CONCLUSIONS

These results show that a topographical analysis of the mERG is useful for clinical observation of CSC.

Human cortical areas activated in relation to vergence eye movements-a PET study

Human cortical areas activated in relation to vergence eye movements were determined using positron emission tomography. Binocular disparity-driven visual stimuli were presented using a head-mounted display. Eye movements were monitored continuously by an infrared limbus tracker. A combination of a bar and a cross was used as the target. In the vergence task, subjects were instructed to follow an approaching bar, while ignoring a stationary cross. Activation in relation to vergence eye movement was discriminated from activation in relation to motion vision by using the ignore-bar task as the control. In the ignore-bar task, subjects were instructed to fixate on a stationary cross, while ignoring an approaching bar. The fixation task was used as the basic control for both the vergence and the ignore-bar tasks. Areas of activation in relation to vergence eye movements were found in the bilateral temporooccipital junction, the left inferior parietal lobule, and the right fusiform gyrus by comparing regional cerebral flow between the vergence and ignore-bar tasks and by the conjunctive analyses of vergence-vs-ignore comparison with vergence-vs-fixation comparison.

Coordinate induction of peroxisomal acyl-CoA oxidase and UCP-3 by dietary fish oil: a mechanism for decreased body fat deposition

Rats fed dietary fats rich in 20- and 22-carbon polyenoic fatty acids deposit less fat and expend more energy at rest than rats fed other types of fats. We hypothesized that this decrease in energetic efficiency was the product of: (a) enhanced peroxisomal fatty acid oxidation and/or (b) the up-regulation of genes encoding proteins that were involved with enhanced heat production, i.e. mitochondrial uncoupling proteins (UCP-2, UCP-3) and peroxisomal fatty acid oxidation proteins. Two groups of male Fisher 344 rats 3-4 week old (n=5 per group) were pair fed for 6 weeks a diet containing 40% of its energy fat derived from either fish oil or corn oil. Epididymal fat pads from rats fed the fish oil diet weighed 25% (P < 0.05) less than those found in rats fed corn oil. The decrease in fat deposition associated with fish oil ingestion was accompanied by a significant increase in the abundance of skeletal muscle UCP-3 mRNA. The level of UCP-2 mRNA skeletal muscle was unaffected by the type of dietary oil, but the abundance of UCP-2 mRNA in the liver and heart were significantly lower (P < 0.05) in rats fed fish oil than in rats fed corn oil. In addition to inducing UCP-3 expression, dietary fish oil induced peroxisomal acyl-CoA oxidase gene expression 2-3 fold in liver, skeletal muscle and heart. These data support the hypothesis that dietary fish oil reduces fat deposition by increasing the expression of mitochondrial uncoupling proteins and increasing fatty acid oxidation by the less efficient peroxisomal pathway.

[Multifocal electroretinograms in patients with branch retinal artery occlusion]

PURPOSE

We recorded multifocal electroretinograms (m-ERGs) in patients with branch retinal artery occlusion (BRAO) and compared the waveform in the area of retinal artery occlusion with that in the normal area, to evaluate the influence of the damage of the inner retina on the m-ERG.

SUBJECTS AND METHODS

Three patients who had normal visual acuity and visual field loss of more than one quadrant due to BRAO were examined. The waveform of first-order and second-order kernel responses of m-ERG in the area of retinal artery occlusion were compared with those of the vertically symmetrical, normally perfused area of the same eye.

RESULTS

Prolongation of latency and decrease of amplitude were noted for the first negative wave (N 1), the first positive wave (P1), and the second negative wave (N2) in the first-order kernel responses in the area of retinal artery occlusion in comparison with the normally perfused area. Second-order kernel responses were not detected in the area of retinal artery occlusion.

CONCLUSIONS

The damage to the inner retina affected portions N1, P1, and N2 of the first-order kernel responses, and N2 was the most seriously affected. Second-order kernel responses appear to reflect more strongly the function of the inner retina.

Axin prevents Wnt-3a-induced accumulation of beta-catenin

When Axin, a negative regulator of the Wnt signaling pathway, was expressed in COS cells, it coeluted with glycogen synthase kinase-3beta (GSK-3beta), beta-catenin, and adenomatous polyposis coli protein (APC) in a high molecular weight fraction on gel filtration column chromatography. In this fraction, GSK-3beta, beta-catenin, and APC were co-precipitated with Axin. Although beta-catenin was detected in the high molecular weight fraction in L cells on gel filtration column chromatography, addition of conditioned medium expressing Wnt-3a to the cells increased beta-catenin in the low molecular weight fraction. However, Wnt-3a-dependent accumulation of beta-catenin was greatly inhibited in L cells stably expressing Axin. Axin also suppressed Wnt-3a-dependent activation of Tcf-4 which binds to beta-catenin and acts as a transcription factor. These results suggest that Axin forms a complex with GSK-3beta, beta-catenin, and APC, resulting in the stimulation of the degradation of beta-catenin and that Wnt-3a induces the dissociation of beta-catenin from the Axin complex and accumulates beta-catenin.

Antibodies specific to outer membrane antigens of Moraxella catarrhalis in sera and middle ear effusions from children with otitis media with effusion

OBJECTIVE

Recent studies have shown that bacterial DNA is present in a significant percentage of middle ear effusions, suggesting that persistent bacterial infection may be more important in pathogenesis and recurrence of otitis media with effusion (OME) than previously considered. Although Moraxella (M.) catarrhalis is one of the most common pathogens of otitis media, relatively little is known about immune response to the organism. The objective of the present study is to investigate how systemic and local immune activities against M. catarrhalis may be associated with severity of OME.

METHODS

The antibody levels specific to outer membrane antigens of M. catarrhalis in sera and middle ear effusions (MEEs) from 59 children with OME were measured by enzyme-linked immunosorbent assay. Their ages ranged from 1 to 12 years with a median 5.0 years. The children were followed 1 year prospectively and classified into two groups with or without recurrent/persistent OME according to severity of OME during the follow-up 1 year.

RESULTS

Serum IgG, IgM, and IgA antibodies specific to outer membrane antigens of M. catarrhalis were detected in all samples and the median levels were 35, 0.93, and 1.2 microg/ml respectively. The MEE IgG, IgM, IgA, and secretory IgA antibodies were detected in over 95% samples tested and the median levels were 371, 158, 20, and 50 ng/mg total protein respectively. A comparison between acute and subacute/chronic phases revealed that the median levels of MEE IgG and IgM antibodies were higher at the acute phase (692 vs. 340, P = 0.06; 35 vs. 10, P = 0.02, respectively); while the MEE secretory IgA antibody level was increased at the subacute/chronic phase (74 vs. 35, P = 0.02). Either serum or MEE IgG antibody level was significantly lower in recurrent/persistent OME group than that in nonrecurrent/non-persistent OME group (13 vs. 43 ,microg/ml, P = 0.009; 238 vs. 577 ng/mg protein, P = 0.006, respectively).

CONCLUSIONS

These data provide additional information on the immunologic aspects of children with OME. Decreased serum and MEE IgG antibody levels specific to outer membrane antigens of M. catarrhalis may lead to failure to eliminate this organism, resulting in persistent and/or recurrent appearance of MEE.

Cytoskeletal reorganization by soluble Wnt-3a protein signalling

BACKGROUND

Wnt-3a is an intercellular signalling molecule that is involved in a variety of morphogenetic events. However, the molecular mechanisms underlying Wnt-3a signalling are poorly understood. We have sought to establish in vitro systems to assay the activity of this protein and investigate its biological roles.

RESULTS

We prepared mouse L cells transfected with Wnt-3a cDNA, and found that their beta-catenin protein level was up-regulated. When conditioned medium (CM) was collected from cultures of the transfectants and added to nontransfected L cells, the beta-catenin level of the latter was also increased. Approximately 50% of the Wnt-3a proteins synthesized by the transfectants were secreted into the CM in a soluble form. These secreted Wnt-3a proteins formed an activity gradient in the environment surrounding the transfectants. Then, we studied whether Wnt-3a had any effect on cellular behaviour in vitro. When the CM containing Wnt-3a (W3a-CM) was added to cultures of C57MG mammary epithelial cells, their morphology was altered to exhibit closer intercellular contacts. Immunostaining for various adhesion and cytoskeletal proteins showed that the actin-microfilamental system was re-organized by the W3a-CM treatment. It induced a directional alignment of actin stress fibres and other actin-associated proteins. Moreover, villin, localized only at the perinuclear regions in untreated C57MG cells, was re-distributed to the leading edges of the cells, co-localizing with F-actin, in the presence of Wnt-3a.

CONCLUSION

Our findings suggest that Wnt-3a protein, in the soluble form, can act to re-organize cytoskeletal structures.

[Detection of isotype-specific autoantibodies to calpastatin in sera from patients with rheumatic diseases using heat-treated HeLa cell extract as an antigen source for immunoblotting]

To detect immunoglobulin isotype-specific autoantibodies to native human calpastatin in patients with rheumatic diseases, we performed immunoblot analysis using the heated HeLa cell extracts to enrich heat-resistant calpastatin. The calpastatin molecule that was apparently migrated to 110 kD by SDS-PAGE was confirmed to react with monoclonal anti-human calpastatin antibody in immunoblotting. IgG antibodies to calpastatin were detected in 22 of 48 sera (46%) from patients with RA, whereas only 20% (5/25), 11% (2/19) and 13% (2/15) of sera from SLE, SSc and PM/DM had IgG anti-calpastatin antibodies, respectively. IgM antibodies were also found in 40% (19/48) of RA and 12% (3/25) of SLE patients but not detected in sera from patients with other rheumatic diseases. IgA antibodies were found in only one RA and one SLE serum. In RA, 7 of 48 sera (15%) had IgM antibodies alone, but all SLE sera with IgM antibodies had IgG antibodies. Thus, anti-calpastatin autoantibodies were detected by using the native human calpastatin. Although these autoantibodies were found in patients with various rheumatic diseases, they were present in RA patients at the highest frequency. In particular, the presence of IgM antibodies appeared to be more specific in RA patients.

Specific interactions and potential functions of human TAFII100

Human transcription initiation factor TFIID contains the TATA-binding protein (TBP) and several TBP-associated factors (TAFs). To investigate the structural organization and function of TFIID, we have cloned and expressed a DNA encoding the third largest human TFIID subunit, hTAFII100. Immunoprecipitation studies demonstrate that hTAFII100 is an integral subunit that is associated with all transcriptionally-competent forms of TFIID. They further suggest that at least part of the N-terminal region lies on the surface of TFIID, while a C-terminal region containing conserved WD-40 repeats appears inaccessible. Both in vivo and in vitro assays indicate that hTAFII100 interacts strongly with the histone H4-related hTAFII80 and the histone H3-related hTAFII31, as well as a stable complex comprised of both hTAFII80 and hTAFII31. Apparently weaker interactions of hTAFII100 with TBP, hTAFII250, hTAFII28, and hTAFII20, but not hTAFII55, also have been observed. These results suggest a role for hTAFII100 in stabilizing interactions of TAFs, especially the histone-like TAFs, in TFIID. In addition, functional studies show that anti-hTAFII100 antibodies selectively inhibit basal transcription from a TATA-less initiator-containing promoter, relative to a TATA-containing promoter, suggesting a possible core promoter-specific function for hTAFII100.

Traumatic cervical tracheal disruption: report of two cases

We report herein the cases of two patients who suffered tracheal disruption, both of whom underwent successful surgical treatment. The first patient was a 48-year-old truck driver who suffered severe dyspnea after jamming his neck in a truck door. An endotracheal tube was unable to be inserted due to bleeding and thus, an emergency tracheostomy was performed. On admission massive subcutaneous emphysema was noted in the neck and anterior chest, and tracheal disruption was confirmed by a lateral neck X-ray, computed tomography (CT), and fiberscopy. An emergency end-to-end anastomosis of the trachea with insertion of a T-type silicon tube into the lower trachea was performed. The second patient was a 36-year-old man who suffered severe dyspnea after having his neck caught in a chain while driving a motorcycle. On admission, marked subcutaneous emphysema in the neck and paradoxical movement of the trachea were noted. Tracheal disruption was confirmed by a lateral neck X-ray and CT, and a similar operation to that of the first patient was performed. This type of injury is rare; however, lateral neck X-ray, CT, and fiberscopy proved extremely useful for making an accurate diagnosis following which successful emergency surgery was able to be performed, achieving good long-term results.

Evolutionary conservation of human TATA-binding-polypeptide-associated factors TAFII31 and TAFII80 and interactions of TAFII80 with other TAFs and with general transcription factors

Human transcription initiation factor TFIID is composed of the TATA-binding polypeptide (TBP) and at least 13 TBP-associated factors (TAFs) that collectively or individually are involved in activator-dependent transcription. To investigate protein-protein interactions involved in TFIID assembly and in TAF-mediated activator functions, we have cloned and expressed cDNAs encoding human TAFII80 and TAFII31. Coimmunoprecipitation assays showed that TAFII80 interacted with TAFII250, TAFII31, TAFII20, and TBP, but not with TAFII55. Similar assays showed that TAFII80 interacted with TFIIE alpha and with TFIIF alpha (RAP74) but not with TFIIB, TFIIE beta, or TFIIF beta (RAP30). Further studies with TAFII80 mutations revealed three distinct interaction domains which fall within regions conserved in human TAFII80, Drosophila TAFII60, and yeast TAFII60. The N terminus of TAFII80 (residues 1-100) interacts with both TAFII31 and TAFII20, while two C-terminal regions are involved, respectively, in interactions with TAFII250 and TFIIF alpha (RAP74) (residues 203-276) and with TBP and TFIIE alpha (residues 377-505). The interactions between TAFII80 and general factors TFIIE alpha and TFIIF alpha (RAP74) could be important for recruitment of GTFs during activator-dependent transcription. Because TAFs 80, 31, and 20 show sequence similarities to histones H4, H3, and H2B, as well as some parallel interactions, this subset of TAFs may form a related core structure within TFIID.

Consumption of carbohydrate or medium- or long-chain triglycerides by unfed rats exerts different protein-sparing effects

Consumption of nonprotein energy is reported to promote nitrogen retention (the protein-sparing effect). The present study was conducted to determine whether consumption of medium-chain triglycerides (MCT), long-chain triglycerides (LCT) or carbohydrate by unfed rats would exert different protein-sparing effects over 48 h. The amounts of MCT, LCT and carbohydrate were adjusted to be isoenergetic. The control group received only water. The urinary excretion of urea in the groups fed carbohydrate or MCT was significantly lower than in the LCT and control groups within the first 24 h. Urinary excretion of urea in the group fed LCT was similar to that of the control group for the first 24 h but was significantly lower after 48 h. Liver serine dehydratase activities in the groups fed MCT or LCT were similar, although they were significantly lower than in the control group. Serine dehydratase activity in the carbohydrate-fed group was the lowest. Liver L-lysine-2-oxoglutarate reductase activity was significantly lower in the groups fed carbohydrate, MCT or LCT than in the control group. Rats fed MCT had the lowest plasma concentrations of lysine and branched-chain amino acids. However, the plasma concentration of glutamic acid in the rats fed MCT was the highest. These results indicate that rats fed MCT, LCT or carbohydrate exhibit different protein-sparing effects and that the difference between rats fed MCT and those fed LCT is not attributable to differences in amino acid-degrading enzymes. Consumption of MCT may conserve some amino acid-derived nitrogen as glutamic acid.

Distribution of Sonic hedgehog peptides in the developing chick and mouse embryo

Sonic hedgehog (Shh) encodes a signal that is implicated in both short- and long-range interactions that pattern the vertebrate central nervous system (CNS), somite and limb. Studies in vitro indicate that Shh protein undergoes an internal cleavage to generate two secreted peptides. We have investigated the distribution of Shh peptides with respect to these patterning events using peptide-specific antibodies. Immunostaining of chick and mouse embryos indicates that Shh peptides are expressed in the notochord, floor plate and posterior mesenchyme of the limb at the appropriate times for their postulated patterning functions. The amino peptide that is implicated in intercellular signaling is secreted but remains tightly associated with expressing cells. The distribution of peptides in the ventral CNS is polarized with the highest levels of protein accumulating towards the luminal surface. Interestingly, Shh expression extends beyond the floor plate, into ventrolateral regions from which some motor neuron precursors are emerging. In the limb bud, peptides are restricted to a small region of posterior-distal mesenchyme in close association with the apical ectodermal ridge; a region that extends 50–75 microns along the anterior-posterior axis. Temporal expression of Shh peptides is consistent with induction of sclerotome in somites and floor plate and motor neurons in the CNS, as well as the regulation of anterior-posterior polarity in the limb. However, we can find no direct evidence for long-range diffusion of the 19 × 10(3) Mr peptide which is thought to mediate both short- and long-range cell interactions. Thus, either long-range signaling is mediated indirectly by the activation of other signals, or alternatively the low levels of diffusing peptide are undetectable using available techniques.

[Relationship between birch pollen allergy and oral and pharyngeal hypersensitivity to fruit]

We evaluated the relationship between birch pollen allergy and oral and pharyngeal hypersensitivities to certain fruits. 1. Of 171 birch pollen CAP positive (score > or = 2) patients, twenty two (13%) were revealed to be hypersensitive to apples, eleven (6%) to be hypersensitive to peaches, both rates being higher than those found in patients with other CAP positive reactions (orchard grass pollen CAP, mugwort pollen CAP or Dermatophagoides pteronyssius CAP positive). 2. Among the birch pollen CAP positive patients, the higher the CAP score for birch pollen, the higher the prevalences of hypersensitivity to apples and peaches were found to be. 3. Of 171 birch pollen CAP positive patients, six (3.5%) were revealed to be hypersensitive to kiwi fruit. Of 253 patients with other CAP positive reactions, three (1%) were revealed to be hypersensitive to kiwi fruit.

Requirement of 19K form of Sonic hedgehog for induction of distinct ventral cell types in CNS explants

The identity and patterning of ventral cell types in the vertebrate central nervous system depends on cell interactions. For example, induction of a specialized population of ventral midline cells, the floor plate, appears to require contact-mediated signalling by the underlying notochord, whereas diffusible signals from the notochord and floor plate can induce ventrolaterally positioned motor neurons. Sonic hedgehog (Shh), a vertebrate hedgehog-family member, is processed to generate two peptides (M(r) 19K and 26/27K) which are secreted by both of these organizing centres. Moreover, experiments in a variety of vertebrate embryos, and in neural explants in vitro, indicate that Shh can mediate floor-plate induction. Here we have applied recombinant Shh peptides to neural explants in serum-free conditions. High concentrations of Shh bound to a matrix induce floor plate and motor neurons, and addition of Shh to the medium leads to dose-dependent induction of motor neurons. All inducing activity resides in a highly conserved amino-terminal peptide (M(r) 19K). Moreover, antibodies that specifically recognize this peptide block induction of motor neurons by the notochord. We propose that Shh acts as a morphogen to induce distinct ventral cell types in the vertebrate central nervous system.

Proteolytic processing yields two secreted forms of sonic hedgehog

Sonic hedgehog (Shh) is expressed in tissues with known signalling capacities, such as the notochord, the floor plate of the central nervous system, and the zone of polarizing activity in the limb. Several lines of evidence indicate that Shh is involved in floor plate induction, somite patterning, and regulation of anterior-posterior polarity in the vertebrate limb. In this report, we investigate the biochemical behavior of Shh in a variety of expression systems and embryonic tissues. Expression of mouse Shh in Xenopus oocytes, COS cells, and baculovirus-infected insect cells demonstrates that in addition to signal peptide cleavage and N-linked glycosylation, chicken and mouse Shh proteins undergo additional proteolytic processing to yield two peptides with molecular masses of approximately 19 kDa (amino terminus) and 27 kDa (carboxy terminus), both of which are secreted. In transfected COS cells, we show that the 19-kDa peptide does not accumulate significantly in the medium unless heparin or suramin is added, suggesting that this peptide associates with the cell surface or extracellular matrix. This retention appears to depend on sequences in the carboxy-terminal part of the peptide. Finally, detection of the 19-kDa product in a variety of mouse and chicken embryonic tissues demonstrates that the proteolytic processing observed in cell culture is a normal aspect of Shh processing in embryonic development. These results raise the possibility that amino- and carboxyl-terminal regions of Shh may have distinct functions in regulating cell-cell interactions in the vertebrate embryo.

Dietary gamma-linolenic acid-enriched oil reduces body fat content and induces liver enzyme activities relating to fatty acid beta-oxidation in rats

The objectives of this study were to examine the effects of dietary gamma-linolenic acid-enriched oil extracted from fungi on rat body composition and on the various enzyme activities relating to fat metabolism in the liver. The oil contained 25.3 g gamma-linolenic acid/100 g fatty acids. The levels of gamma-linolenic acid-enriched oil in the diets were 0, 1.5 and 4%, to give 0, 2.88 and 7.68 g gamma-linolenic acid/kg diet. The control diet contained 8% soybean oil. The rats were given free access to these diets for 4 wk. Body weight gain was less in the gamma-linolenic acid oil-fed groups than in the control group, although food intake was similar among the three groups. Absolute and relative carcass fat weights were significantly lower in the gamma-linolenic acid oil-fed groups than in the control group. Carcass protein and water contents were not different among the three groups, although values were slightly greater than controls in gamma-linolenic acid-fed groups when expressed relative to body weight. Plasma total cholesterol and free fatty acid concentrations generally were lower in the gamma-linolenic acid oil-fed groups than in the control group. In the liver, there were no significant differences in activities of malic enzyme and citrate cleavage enzyme among the three groups. However, the activities of carnitine palmitoyl-transferase and peroxisomal beta-oxidation were significantly higher in the gamma-linolenic acid oil-fed groups than in the control group. These results clearly demonstrate that dietary gamma-linolenic acid oil reduces body fat content and facilitates fatty acid beta-oxidation in the liver.

Molecular cloning, expression, and characterization of the Drosophila 85-kilodalton TFIID subunit

Transcription initiation factor TFIID is a multimeric protein complex that plays a central role in mediating promoter responses to various activators and repressors. To further understand the role of the 85-kDa TFIID subunit (p85), we have cloned the corresponding cDNA with a probe based on an amino acid sequence of the purified protein. The recombinant p85 interacts directly with both the TATA box-binding subunit (TFIID tau or TBP) and the 110-kDa subunit (p110) of TFIID, suggesting that p85 may play a role in helping to anchor p110 within the TFIID complex and, with other studies, that TFIID assembly and function may involve a concerted series of subunit interactions. Interestingly, the carboxy terminus of p85 contains eight of the WD-40 repeats found originally in the beta subunit of G proteins and more recently in other transcriptional regulatory factors. However, truncated p85 lacking all the WD-40 repeats maintained interactions with both TFIID tau and p110. These observations leave open the possibility of a distinct function for the WD-40 repeats, possibly in transducing signals by interactions with transcriptional regulators and/or other components of the basic transcriptional machinery.

Effects of long- and medium-chain triglycerides on amino acid uptake in rat intestinal brush border membrane vesicles

1. Uptake of L-leucine, L-phenylalanine, L-proline and L-lysine into brush border membrane vesicles from rats fed either a medium-chain triglyceride (MCT) or a long-chain triglyceride (LCT) diet was studied under conditions of the presence of absence of a Na+ gradient. 2. From the results of initial rate, Na(+)-dependent transport in LCT feeding were lower than in feeding MCT. The Na(+)-independent transport did not vary in either group except for L-lysine uptake. 3. For L-leucine, L-phenylalanine and L-proline in Na+ dependence, kinetic analysis revealed 4-6-fold smaller Vmax values in LCT group than in MCT group. L-Lysine in Na(+)-independent transport was 10-fold lower in LCT group than in MCT group. The Km values were not affected by feeding the LCT or MCT diet. 4. It is clear that amino acid transport is regulated by different types of dietary fat. We consider that the alteration of transport activity is attributable to the changes in number of membrane-bound transport carriers but not to their affinity.

Identification of TFIID components required for transcriptional activation by upstream stimulatory factor

A TATA box-binding initiation factor, TFIID, plays a central role in the transcriptional regulation by activators. Using anti-TFIID tau (a TATA box-binding component of native TFIID) immunoaffinity chromatography, nine polypeptides (230, 110, 85, 62, 58, 42, 28, 22, and 21 kDa) were identified as native Drosophila TFIID components that are tightly associated with TFIID tau. To verify the functional activity of the purified TFIID complex, template DNA and other transcription factors were reconstituted with purified TFIID bound to the antibody-Sepharose matrix. Immobilized TFIID mediated not only basal transcription but transcriptional activation by upstream stimulatory factor (USF). On the other hand, recombinant TFIID tau immobilized on the same antibody-Sepharose matrix could not mediate activation by USF. These results suggest that one or more of these additional polypeptides are required as functional TFIID subunits for activator-dependent transcription in conjunction with TFIID tau. As further evidence of the relevance of the Drosophila TFIID components identified in this analysis, including the previously unrecognized p230 (Dynlacht, B. D., Hoey, T., and Tjian, R. (1991) Cell 66, 563-576), protein blot analysis showed that TFIID tau interacts specifically and exclusively with p230. This suggests that p230 is an integral subunit of TFIID and that it may play a major role in tethering other subunits to TFIID tau.

Molecular cloning of the cDNAs for the four subunits of mouse DNA polymerase alpha-primase complex and their gene expression during cell proliferation and the cell cycle

The DNA polymerase alpha-primase complex purified from mouse FM3A cells is composed of four polypeptides with molecular masses of 180, 68, 54, and 46 kDa. The largest subunit has DNA polymerase activity, the two smallest subunits have DNA primase activity, and the function of the 68-kDa subunit is unknown. We have isolated the cDNAs of the four subunits by low stringency hybridization and reverse transcription polymerase chain reaction and determined their nucleotide sequences. The predicted amino acid sequence of the 180-kDa subunit shows 88, 38, 34, and 32% identity to those of the catalytic subunits of human, Drosophila melanogaster, Schizosaccharomyces pombe, and Saccharomyces cerevisiae DNA polymerase alpha, respectively, and contains seven regions whose orders and sequences are highly conserved among viral and other eukaryotic DNA polymerases. The deduced amino acid sequence of the 68-kDa subunit shows 25% identity to that of the 73-kDa subunit of D. melanogaster DNA polymerase alpha-primase, shows no significant sequence similarity to any other protein in the data bases, but contains a potential phosphorylation site(s) for cdc2 kinase. The amino acid sequence of the 54-kDa subunit shows 32% identity to that of the large subunit of S. cerevisiae DNA primase. During activation of quiescent Swiss mouse 3T3 cells to proliferate, the levels of mRNA of the four subunits of the DNA polymerase alpha-primase complex increased before DNA synthesis. In growing mouse FM3A cells, the transcripts of the four subunits are present throughout the cell cycle and increase slightly prior to the S phase.