Vitreous hemorrhage as an ophthalmic complication of galactosemia

A major complication of galactosemia is cataracts. This is usually considered to be the sole ophthalmic feature of this disorder. However, we have encountered vitreous hemorrhage, a very rare ophthalmic finding, in five neonates with galactosemia and have found four probable additional cases in the literature. All of these infants had severe neonatal manifestations of galactosemia and were discovered to have vitreous hemorrhage by ophthalmologic examination initiated by the observation of clouding of the eye or on a routine basis. The infants lost most or all vision from the affected eye. Retinal abnormalities were present in the involved eyes of the five neonates of whom we have direct knowledge. Thus we believe that retinal hemorrhage is the most likely source of the vitreous hemorrhage and that the coagulopathy associated with neonatal disease in galactosemia leads to vitreous hemorrhage. Prompt recognition and therapy for the coagulopathy would likely prevent vitreous hemorrhage in galactosemia.

Impact of cholesterol reduction on peripheral arterial disease in the Program on the Surgical Control of the Hyperlipidemias (POSCH)

BACKGROUND

Few lipid/atherosclerosis intervention trials have assessed the impact of cholesterol reduction on peripheral arterial disease. The 838 patients evaluated in the Program on the Surgical Control of the Hyperlipidemias (POSCH) trial represent more than the total number of patients in the seven previously reported studies.

METHODS

Peripheral arterial disease in POSCH was assessed by progression of clinical disease, serial changes in the systolic blood pressure ankle/brachial index (ABI), and changes on sequential peripheral arteriograms.

RESULTS

At the time of formal closure of the POSCH trial on July 19, 1990, claudication or limb-threatening ischemia was exhibited in 72 of 417 control group (CG) patients and in 54 of 421 intervention group (IG) patients (IG relative risk [RR] 0.702, 95% confidence interval [CI] 0.169 to 1.000, p = 0.049). With additional follow-up evaluation to September 30, 1994, clinical peripheral arterial disease was evident in 91 CG patients and 64 IG patients (RR 0.656, 95% CI 0.200 to 0.903, p = 0.009). At the 5-year follow-up evaluation, an ABI of less than 0.95 was present in 41 of 120 CG patients and in 24 of 126 IG patients, all of whom had an ABI of 0.95 or greater at baseline (RR in the IG of 0.557, 95% CI 0.360 to 0.863, p < 0.01). No appreciable differences were noted in the progression or regression of arteriographic peripheral arterial disease between the two groups.

CONCLUSIONS

Effective cholesterol reduction in POSCH led to statistically significant differences between the control and the intervention groups in the development of clinically evident peripheral arterial disease and in the ABI values, but not in the peripheral arteriograms. Additional studies need to assess the correlation between peripheral arterial changes and coronary arterial changes and clinical atherosclerosis events. Intervention trials that study peripheral arterial disease have intrinsic value in the evaluation of the impact of risk factor modification on progression of atherosclerotic peripheral arterial disease.

Gender-based mortality follow-up from the Program on the Surgical Control of the Hyperlipidemias (POSCH) and meta-analysis of lipid intervention trials. Women in POSCH and other lipid trials

OBJECTIVE

The authors assessed the clinical results of lipid-lowering therapy in women.

SUMMARY BACKGROUND DATA

The Program on the Surgical Control of the Hyperlipidemias (POSCH) has demonstrated that effective lowering of total cholesterol and low-density lipoprotein cholesterol in a postmyocardial infarction population significantly reduces atherosclerotic coronary heart disease (ACHD) mortality, ACHD mortality combined with a new confirmed nonfatal myocardial infarction, and the number of coronary artery bypass grafting and angioplasty procedures performed.

METHODS

A review and meta-analysis were performed of the seven primary or secondary lipid/ atherosclerosis intervention trials-including POSCH-published in the English-language literature that included women and published results in women separate from the results in men or in the entire trial population. The main outcome measure analyzed was overall mortality.

RESULTS

The Scottish Physicians Clofibrate Study, the Newcastle upon Tyne Clofibrate Study, and the Pravastatin Limitation of Atherosclerosis in the Coronary Arteries (PLAC I) Trial may have demonstrated a possible benefit in ACHD prognosis from effective lipid intervention in women. The other four available trials did not. The Minnesota Coronary Survey reported a 15.6% increase in overall mortality rate and a 30.6% increase in a combined cardiovascular endpoint rate in the lipid-intervention group. The Upjohn Colestipol Study demonstrated statistically significant reductions in overall and ACHD mortality in the men, but not in the women. The Scandinavian.

Disease-free intervals after partial ileal bypass in patients with coronary heart disease and hypercholesterolemia: report from the Program on the Surgical Control of the Hyperlipidemias (POSCH)

OBJECTIVES

We sought to analyze the disease-free intervals and calculate the freedom from atherosclerosis events in the Program on the Surgical Control of the Hyperlipidemias (POSCH).

BACKGROUND

The POSCH study was a randomized, secondary lipid/atherosclerosis intervention trial that provided strong evidence for reduction in atherosclerosis progression as demonstrated by clinical and arteriographic end points. The 417 control group patients received American Heart Association phase II diet instruction, and the 421 intervention group patients received identical dietary instruction and underwent a partial ileal bypass operation.

METHODS

Four outcome measures were determined: 1) overall mortality, 2) coronary heart disease mortality, 3) coronary heart disease mortality and confirmed nonfatal myocardial infarction, and 4) coronary/cardiac interventions.

RESULTS

An overall mortality rate of 10% occurred at 6.7 years in the control group and 9.4 years in the intervention group, for a gain in disease-free interval of 2.7 years in the intervention group (p = 0.032). A coronary heart disease mortality rate of 8% occurred at 7.2 years in the control group and 11 years in the intervention group, for a gain of 3.8 years (p = 0.046). Twenty percent of patients demonstrated the combined end point of coronary heart disease mortality and confirmed nonfatal myocardial infarction at 5.9 years in the control group and 11.4 years in the intervention group, for a gain of 5.5 years (p < 0.001). Twenty-five percent of patients underwent either coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty or heart transplantation at 5.4 years in the control group and 12.4 years in the intervention group, for a gain of 7 years (p < 0.001).

CONCLUSIONS

The marked lipid modification achieved by partial ileal bypass in the POSCH trial led to demonstrable increases in the disease-free intervals for overall mortality, coronary heart disease mortality, coronary heart disease mortality and confirmed nonfatal myocardial infarction, and coronary intervention procedures. For the clinician and the patient, estimation of disease-free intervals may be more relevant than assessment of differences in incidence rates and risk ratios.

The effects of topic and listener familiarity on discourse variables in procedural and narrative discourse tasks

This study investigated the effects of listener and topic familiarity on procedural and narrative discourse variables. Twenty-two aphasic patients (5 Broca's, 7 conduction, and 10 anomic aphasics) and 10 normal speakers served as subjects. Topic familiarity influenced discourse production in both procedural discourse and story retell situations. In procedural discourse, a greater number of optional steps were provided with familiar topics. During retelling of familiar topic stories, a greater proportion of action and resolution clauses were included. Listener familiarity affected the story retell task only. A greater percentage of subjects provided the setting when the listener was familiar.

The influence of topic and listener familiarity on aphasic discourse

This study investigated the effects of listener and topic familiarity on verbal output. A total of 32 subjects were included: 5 Broca's, 7 conduction, and 10 anomic aphasics; and 10 normal controls. Subjects performed story retell and procedural discourse tasks containing familiar and unfamiliar topics. Tasks were completed with a familiar listener (spouse) and an unfamiliar listener (examiner). Results indicated that topic familiarity significantly influenced verbal output, however specific findings were dependent on task. In procedural discourse, the amount of verbal output (number of T-units) was significantly greater on familiar topics. In contrast, the complexity (number of words and clauses per T-unit) was significantly greater on unfamiliar topics. On story retell, verbal output (number of T-units) was also greater on familiar topics. However, grammatic complexity did not increase with unfamiliar topics. Words per T-unit remained higher on familiar topics. The variable of listener familiarity was not found to be significant.

Effect of porcine somatotropin (pST) treatment and withdrawal on performance and adipose tissue cellularity in finishing swine

A 10-wk trial was conducted with 60 barrows and 60 gilts (initial weight = 47 kg) to investigate the effect of pST treatment (3 mg/d) for wk 0 to 5, 5 to 10, or 0 to 10 on performance, carcass traits, and adipose tissue cellularity of finishing hogs. The primary objective of the study was to determine the effect of 5 wk of pST treatment followed by 5 wk of withdrawal on performance and carcass traits relative to a control or to pigs treated for the entire period. After 5 wk, pST-treated pigs exhibited improved (P < .001) gain (11%) and efficiency (22%) and decreased (P < .001) feed intake (-22%) and 10th rib backfat accretion (-93%, P < .001). There was an increase in adipose cell number/gram of tissue (control, 2.57 vs pST, 3.36 x 10(6)/g; P < .005) and a decrease in cell diameter (control, 72.4 vs pST, 67.2 microns; P < .005). Backfat thickness and cell diameter increased in control pigs from wk 5 to 10. During the last 5-wk period, pST-treated animals continued to exhibit improved performance and maintained adipose cell size distribution and number similar to the pST-treated pigs at wk 5. Pigs treated for the first 5 wk and withdrawn from treatment for the second 5 wk had decreased efficiency (-12%, P < .05) and a twofold increase in backfat accretion (P < .001) relative to control. The increase in backfat thickness was accompanied by an increase in adipocyte diameter, indicative of lipid filling. Most of the benefits of pST observed during the first 5 wk were lost during the withdrawal period. Reductions in carcass fat in response to pST treatment are at least partially accounted for by inhibition of lipid filling in adipose tissue, an effect that is reversed upon cessation of treatment.

Foodservice industry market profile study: nutritional and objective textural profile of foodservice ground beef

Ground beef patties of three types (regular, lean, extra-lean) destined for the foodservice industry were collected from foodservice purveyors in 12 cities equally distributed across six geographical regions of the United States to assess nutritional and objective texture characteristics. Patties were cooked on a foodservice-style clamshell grill to a well (approximately 80 degrees C) degree of doneness (internal temperature) for nutritional analysis and objective texture measurements. Single 5.08-cm2 samples were removed from the center of each patty and sheared with a multiple-blade Allo-Kramer shearing device. Nutritional composition, including proximate analysis values and fatty acid profiles, was determined on both raw and cooked samples of the ground beef. Extra-lean ground beef contained the least (P < .05) fat (12.43%), lean had an intermediate level (17.45%), and regular ground beef contained the most fat (P < .05) (20.20%), on a raw basis. However, after cooking, fat content was similar (P > .05) for regular and lean ground beef. Fatty acid composition of lipid and cholesterol content of ground beef did not differ (P > .05) across types of ground beef or between raw and cooked samples and was similar to USDA Handbook 8-13 values. Cooking loss decreased (P < .05) as fat percentages decreased. Regular and lean ground beef was easier (P < .05) to shear (4.20 and 4.24 kg/g of sample, respectively) than extra-lean ground beef (5.08 kg/g of sample). On average, foodservice ground beef sampled in the present study is 15.5% leaner than retail ground beef as presented in the National Beef Market Basket Survey and 22.2% leaner than USDA Handbook 8-13 values.

Comparison of live and carcass equations predicting percentage of cutability, retail product weight, and trimmable fat in beef cattle

Forty-four Hereford-sired steers were measured ultrasonically for backfat and longissimus muscle area between the 12th and 13th ribs before slaughter and visually appraised for fatness, overall muscling, and frame. Carcass measurements associated with USDA yield and quality grades were measured and recorded. Carcasses were fabricated into closely trimmed, boneless subprimals at 1.27- and .32-cm fat trim levels. Cutability percentage (percentage of retail cuts from the cold carcass weight) and kilograms of retail product were defined three ways. The first definition included only retail cuts from the round, loin, rib, and chuck. The second included the above plus adjusted lean trim from the round, loin, rib, and chuck, and, finally, total retail product from the entire carcass. Kilograms (TOTFAT) and percentage (PERFAT) of trimmable fat were also calculated. Stepwise regression procedures were used for live and carcass trait model development predicting cutability percentages, kilograms of retail product, and trimmable fat. Fat measurements accounted for the largest portion of variation in cutability percentage and PERFAT. Weight measurements accounted for the major sources of variation in predicting kilograms of retail product and TOTFAT. Final models using live animal traits ranked the steers equally as well for cutability percentages as the original USDA cutability equation and stepwise, developed carcass equations (P > .10). Final models using live animal or carcass equations ranked the animals equally for kilograms of retail product yield (P > .10).

The carboxyl-terminal domain of lipoprotein lipase binds to the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) and mediates binding of normal very low density lipoproteins to LRP

Lipoprotein lipase (LPL) binds with high affinity to the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) and promotes binding, uptake, and degradation of normal triglyceride-rich lipoproteins in a process mediated by LRP (Chappell, D. A., Fry, G. L., Naknitx, M.A., Muhonen, L. E., Pladet, M. W., Iverius, P-H., and Strickland, D. K. (1993) J. Biol. Chem. 268, 14168-14175). To localize the portion of LPL that is responsible for interacting with LRP, fragments of LPL were expressed in bacteria. A fragment of human LPL containing the COOH-terminal domain (residues 313-448, designated LPLC) which lacks the catalytic site was able to bind to LRP. Purified LRP bound specifically to microtiter wells coated with LPL or LPLC with KD values of 2.8 and 5 nM, respectively. The effects of several mutations of LPLC were tested. Mutation of Lys407 to Ala reduced the affinity of LPLC for LRP by approximately 10-fold. Like native LPL, LPLC prevented the binding of activated alpha 2-macroglobulin and the 39-kDa receptor-associated protein to LRP and inhibited the internalization and degradation of activated alpha 2-macroglobulin and receptor-associated protein in cultured fibroblasts. LPLC also bound to 125I-labeled human normal triglyceride-rich lipoproteins and promoted their binding to purified LRP and to cultured cells. Mutation of Trp393 and Trp394 to Ala completely abolished the ability of LPLC to bind to lipoproteins, but had little effect on its interaction with LRP. These data indicate that the COOH-terminal domain of LPL may function both in binding lipoproteins and mediating their interaction with LRP.

Early-treated phenylketonuria: adult neuropsychologic outcome

Twenty-five adults with phenylketonuria that was treated early were compared with 15 unaffected control siblings with respect to intellectual and neuropsychologic measures. Patients were found to have normal intelligence but were significantly lower than their control siblings on measures of intelligence, attention, and complex visuoconstructional ability. Stepwise multiple regression analyses found the patients' intellectual outcome to be best predicted by indexes reflecting early insult to the brain, whereas performance on a measure of novel problem solving was best predicted by concurrent serum phenylalanine level. Different pathophysiologic mechanisms may thus account for cognitive deficits in this population. These results provide further evidence of continuing benefits of dietary adherence into adulthood.

Cis,cis-muconate lactonizing enzyme from Trichosporon cutaneum: evidence for a novel class of cycloisomerases in eucaryotes

The absolute stereochemical courses of cis,cis-muconate lactonizing enzyme (MLE;EC 5.5.1.1) from Trichosporon cutaneum (TcMLE) and chloromuconate cycloisomerase (MLE II; EC 5.5.1.7) from Pseudomonas sp B13 have been determined from 1H NMR measurements. Both cycloisomerases convert cis,cis-muconate to (4S)-muconolactone by a syn lactonization, the absolute stereochemical outcome of which is identical to that observed with MLE from Pseudomonas putida. The regiochemical courses of cyclization of 3-halo-cis,cis-muconates by TcMLE and MLE II have been characterized and shown to differ in a halogen substituent dependent manner, suggesting at least a different active site architecture of the two MLEs. Moreover, the regiochemical preferences of MLE II and TcMLE parallel results previously observed for the nonenzymatic lactonization of the 3-halomuconates at pH 1-6 and in concentrated HCl, respectively, in which alternate mechanisms of cyclization were proposed [Pieken, W. A., & Kozarich, J. W. (1990) J. Org. Chem. 55, 3029-3035]. Complementary DNA clones encoding TcMLE have been isolated from phenol induced T. cutaneum cDNA using the polymerase chain reaction. The deduced amino acid sequence does not exhibit any similarity to that of MLE from P. putida. It does however, exhibit moderate sequence similarity (21% residue identity, 14 gaps) with 3-carboxy-cis,cis-muconate lactonizing enzyme (CMLE; EC 5.5.1.5) from Neurospora crassa, which catalyzes a regiochemically analogous and stereochemically identical lactonization reaction with 3-carboxymuconate. The limited data available suggest that the fungal CMLE and yeast MLE are representative of a unique class of eucaryotic cycloisomerases which have evolved convergently with the bacterial MLEs.

Foodservice industry market profile study: in-plant beef fat trim level survey and cutting yields

Fifty foodservice purveying companies were sampled in 12 U.S. cities evenly distributed across six geographical regions. Beef whole muscle cuts (WMC) and portion control items (PCI) from the primal rib and loin were evaluated for surface fat levels. Fat thicknesses were measured on WMC before and after fabrication, whereas additional PCI were measured for fat trim levels before distribution. The average initial fat thickness was 11.9 mm (174 Short Loin and 180A Strip Loin) and 15.6 mm (184 Top Sirloin Butt); maximum fat thicknesses ranged from 16.2 mm (strip loin) to 22.2 mm (top sirloin butt). After fabrication, average fat thicknesses were 6.2, 5.1, and 4.0 mm for resulting products from the short loin, strip loin, and top sirloin butt, respectively. The average initial fat thickness for the strip loin was greater (P < .05) in Southeast and Northeast regions than in Mountain/Desert, Midwest, and Southwest regions. In contrast, average trimmed fat thicknesses for products from the strip loin and top sirloin butt were lower (P < .05) in the Southeast and Northeast than in all other regions. Average fat trim levels for PCI were 3.0 (1112A Ribeye Roll steak, Lip-On), 5.3 (1173B/1174B T-Bone/Porterhouse steak), 5.0 (1180A Strip Loin steak), and 4.0 mm (1184B Top Sirloin steak). Maximum fat trim levels were 4.4 (IMPS 1112A), 7.4 (IMPS 1173B/1174B), 6.9 (IMPS 1180A), and 5.5 mm (IMPS 1184B). The PCI had average and maximum fat trim levels in compliance with USDA (1988) recommendations for fat trim specifications.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prepubertal body weight gain and breed on carcass composition at puberty in beef heifers

Fourteen prepubertal Angus heifers, all of which reached puberty, and 11 Santa Gertrudis (SG) heifers, eight of which reached puberty, were divided into two treatment groups. There was no breed difference in age at puberty for those that reached puberty. Treatment 1 (T1) heifers, fed to gain .5 kg/d, tended (P < .11) to be older than Treatment 2 (T2) heifers, fed to gain 1 kg/d, at puberty. Body weight and height were greater (P < .01) in SG than in Angus heifers at puberty. Angus heifers in T2 deposited more fat over the rump during the 15 wk before puberty, whereas T1 SG heifers deposited the least amount of fat (P < .05). Heifers in T2 were heavier at puberty (P < .05), had faster growing longissimus muscle areas (P < .05), and deposited more fat over the rib (P < .01) as they approached puberty. The T2 (P < .05) and Angus (P < .05) rib sections had more dissectible subcutaneous fat than did T1 and SG rib sections. Angus heifers had higher marbling scores (P < .05), as well as higher total lipid percentages for seam fat (P < .05), longissimus muscle (P < .01), other lean tissue (P < .05), and subcutaneous fat (P < .01). Predicted total lipid content for the edible portion of the dressed carcass was higher for T2 heifers (P < .09).

The impact of aphasia on marital satisfaction

This investigation retrospectively examined changes in marital satisfaction following stroke. The relationship between such changes and other pertinent factors were also examined, including severity of aphasia, knowledge of aphasia, number of months after stroke, and length of the marriage. The subjects were 40 spouses of patients with aphasia grouped according to severity of the aphasia (mild, moderate, severe). Spouses completed two different measures of marital satisfaction--the Marital Satisfaction Scale (MSS) and the Marital Comparison Level Index (MCLI). These measures were completed in both a prestroke (retrospective reporting) and a poststroke format to allow for change to be assessed. In addition, a Knowledge of Aphasia questionnaire was completed by the normal spouses to evaluate their understanding of the disorder of aphasia. There was a significant difference between prestroke and poststroke scores on both the MSS and the MCLI, indicating a lower level of satisfaction following the stroke. The amount of change between prestroke and poststroke MSS and MCLI scores was not related to either number of months poststroke or number of years married. Although there was no relationship between changes in prestroke and poststroke scores on the MCLI and Knowledge of Aphasia scores, there was a significant correlation between changes in these scores on the MSS and Knowledge of Aphasia scores. Hence, the more knowledge spouses had regarding aphasia, the less the negative impact the stroke had on marital satisfaction, as measured by the MSS. Results are discussed in terms of the interdisciplinary treatment needs of aphasic patients and the implications for future investigations.

Pressure-flow characteristics of intramural and total coronary collateral networks

The purpose of the present investigation was to determine the pressure-flow (PF) relationship of intramural collaterals and to determine whether their characteristics differ significantly from those of the total collateral network, defined as the epicardial plus intramural collateral network. Because a significant portion of the collateral flow is diverted away from the retrograde flow measurement, we embolized the coronary vessel on which the retrograde flow was measured with spheres of various sizes until the retrograde flow was maximized and retrograde flow diversion blocked. The PF relationship was obtained before and after the epicardial collaterals were cauterized to determine the characteristics of the total and intramural collateral network. PF data for the collateral circulations were obtained by changing the inflow pressure to all coronary vessels simultaneously and by measuring the retrograde flow while maintaining the retrograde outflow pressure at 0 mmHg. The PF characteristics of the total and intramural collateral circulations could be fitted by either a second-degree polynomial or linear equation. In both cases the pressure intercept crossed the origin of the axes. The average contribution of intramural collaterals to total retrograde flow was 58 +/- 5%. We conclude that the PF characteristics of intramural collaterals parallel those of the total collateral circulation.

Effect of pH and ionic strength on bovine m-calpain and calpastatin activity

The effects of bovine skeletal muscle m-calpain and calpastatin on the degradation of casein and isolated bovine myofibrils were characterized under various pH values (7.0, 6.2, 5.7) and ionic strengths (32 to 400 mM KCl) at 25 degrees C. Caseinolytic assays indicated that m-calpain activity increased with increasing pH (P < .01) but decreased with increasing ionic strength (P < .01). Regardless of the presence of m-calpain, SDS-PAGE of myofibrils showed increased solubilization of myofibrillar proteins as pH and ionic strength increased. However, only in the presence of m-calpain were changes normally observed during postmortem storage reproduced. Protein release attributed to m-calpain activity increased with pH, but the effects of elevated ionic strength on the ability of m-calpain to hydrolyze myofibrillar proteins were not evident from SDS-PAGE, except for the decreased troponin-T degradation by m-calpain at the higher ionic strengths. A pH x ionic strength interaction was observed for calpastatin activity determined by caseinolytic assays (P < .01). No changes in m-calpain inhibition were detected at pH 7.0 and 6.2 at different ionic strengths. However, at pH 5.7 the ability of calpastatin to inhibit m-calpain decreased with increasing ionic strength. No changes in m-calpain inhibition could be detected with SDS-PAGE. Based on these results, it can be concluded that although m-calpain and calpastatin activities decrease with increasing ionic strength, their activities in the presence of myofibrils were not affected by ionic strengths typically found in postmortem muscle.

The low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor binds and mediates catabolism of bovine milk lipoprotein lipase

Lipoprotein lipase (LPL), the major lipolytic enzyme involved in the conversion of triglyceride-rich lipoproteins to remnants, was found to compete with binding of activated alpha 2-macroglobulin (alpha 2M*) to the low density lipoprotein receptor-related protein (LRP)/alpha 2-macroglobulin receptor. Bovine milk LPL displaced both 125I-labeled alpha 2M* and 39-kDa alpha 2M receptor-associated protein (RAP) from the surface of cultured mutant fibroblasts lacking LDL receptors with apparent KI values at 4 degrees C of 6.8 and 30 nM, respectively. Furthermore, LPL inhibited the cellular degradation of 125I-alpha 2M* at 37 degrees C. Because both alpha 2M* and RAP interact with LRP, these data suggest that LPL binds specifically to this receptor. This was further supported by observing that an immunoaffinity-isolated polyclonal antibody against LRP blocked cellular degradation of 125I-LPL in a dose-dependent manner. In addition, 125I-LPL bound to highly purified LRP in a solid-phase assay with a KD of 18 nM, and this binding could be partially displaced with alpha 2M* (KI = 7 nM) and RAP (KI = 3 nM). Taken together, these data establish that LPL binds with high affinity to LRP and undergoes LRP-mediated cellular uptake. The implication of these findings for lipoprotein catabolism in vivo may be important if LRP binding is preserved when LPL is attached to lipoproteins. If so, LPL might facilitate LRP-mediated clearance of lipoproteins.

3-Carboxy-cis,cis-muconate lactonizing enzyme from Pseudomonas putida is homologous to the class II fumarase family: a new reaction in the evolution of a mechanistic motif

The gene (pcaB) for 3-carboxymuconate lactonizing enzyme (CMLE; 3-carboxymuconate cycloisomerase; EC 5.5.1.2) from Pseudomonas putida has been cloned into pMG27NS, a temperature-sensitive expression vector, and expressed in Escherichia coli N4830. The specific activity and kinetic parameters of the recombinant CMLE were comparable to those previously reported. A comparison of the deduced amino acid sequence of CMLE with sequences available in the PIR and Genbank databases revealed that CMLE has highly significant sequence homology to the class II fumarase family, particularly to adenylosuccinate lyase from Bacillus subtilis. CMLE has no significant homology to muconate lactonizing enzyme (MLE) from P. putida, its sister enzyme in the beta-ketoadipate pathway. These findings fully corroborate a prediction made by us on the basis of mechanistic and stereochemical analyses of CMLE and MLE [Chari, R. V. J., Whitman, C. P., Kozarich, J. W., Ngai, K.-L., & Ornston, L. N. (1987) J. Am. Chem. Soc. 109, 5514-5519] and suggest that CMLE and MLE were recruited into this specialized pathway from two different enzyme families.

Carnivorous plants: phylogeny and structural evolution

The carnivorous habit in flowering plants represents a grade of structural organization. Different morphological features associated with the attraction, trapping, and digestion of prey characterize a diversity of specialized forms, including the familiar pitcher and flypaper traps. Phylogenetic analysis of nucleotide sequence data from the plastic rbcL gene indicates that both carnivory and stereotyped trap forms have arisen independently in different lineages of angiosperms. Furthermore, these results demonstrate that flypaper traps share close common ancestry with all other trap forms. Recognition of these patterns of diversification may provide ideal, naturally occurring systems for studies of developmental processes underlying macromorphological evolution in angiosperms.