Comparison of gait kinetics in total and unicondylar knee replacement surgery.

Introduction The aim of this study was to compare kinetical data from gait analysis of patients who have undergone total and uni-condylar knee replacement. Materials and methods Thirteen patients with unilateral total knee arthroplasty (TKA) and 13 unicondylar knee arthroplasty (UKA), were included, all performed by the same surgeon more than one year prior. The Vicon gait analysis system was used. Statistical power was calculated using SPSS. Results No significant difference was found in the spatiotemporal parameters of gait and survival years of the knee prosthesis between the two groups. The UKA group was found to have significantly larger moments than the TKA group in knee adduction on the operated side and knee flexion moment on the unoperated side during the loading phase. The maximum and minimum sagittal plane moments of the operated sides in the TKA group were significantly lower than the unoperated side. The difference was most significant at pre-swing. The maximum and minimum moments on the operated sides in the UKA group were significantly lower for the knee flexion and adduction moments when compared with the unoperated side and were most prevalent during the loading phase. Conclusions These results are relevant in terms of prosthesis wear. The TKA knees had smaller magnitude moments than the UKA knees in the sagittal and coronal planes. This could explain the higher revision rates for UKA. In both groups, the non-operated knees had significantly larger moments than the operated knees, which implies that after unilateral knee replacement of either type, the non-operated knee is being put under greater stress.

Halogenated 2,5-pyrrolidinediones: synthesis, bacterial mutagenicity in Ames tester strain TA-100 and semi-empirical molecular orbital calculations.

The chloroimide 3,3-dichloro-4-(dichloromethylene)-2,5-pyrrolidinedione, a tetrachloroitaconimide, is the principal mutagen produced by chlorination of simulated poultry chiller water. It is the second most potent mutagenic disinfection by-product of chlorination ever reported. Six of seven new synthetic analogs of this compound are direct-acting mutagens in Ames tester strain TA-100. Computed energies of the lowest unoccupied molecular orbital (E(LUMO)) and of the radical anion stability (DeltaH(f)(rad)-DeltaH(f)) from MNDO-PM3 for the chloroimides show a quantitative correlation with the Ames TA-100 bacterial mutagenicity values. The molar mutagenicities of these direct acting mutagenic imides having an exocyclic double bond fit the same linear correlation (lnM(m) vs. E(LUMO); lnM(m) vs. DeltaH(f)(rad)--DeltaH(f)) as the chlorinated 2(5H)-furanones, including the potent mutagen MX, 3-chloro-4-(dichloro-methyl)-5-hydroxy-2(5H)-furanone, a by-product of water chlorination and paper bleaching with chlorine. Mutagenicity data for related haloimides having endocyclic double bonds are also given. For the same number of chlorine atoms, the imides with endocyclic double bonds have significantly higher Ames mutagenicity compared to their structural analogs with exocyclic double bonds, but do not follow the same E(LUMO) or DeltaH(f)(rad)-DeltaH(f) correlation as the exocyclic chloroimides and the chlorinated 2(5H)-furanones.

Leads for insect neuropeptide mimetic development.

Insect neuropeptides mediate a number of physiological processes critical for insect survival. The numerous neuropeptide sequences that have been reported present an opportunity to decipher the chemical and conformational requirements for neuropeptide-receptor interactions. Chemical and conformational requirements for activity represent a "template" from which agonist/antagonist peptide mimetics, with the potential to disrupt critical insect processes, can be developed. Information on structural requirements is presented for three neuropeptide families: the sulfakinins, pyrokinins, and leucokinin/achetakinins, including active core size, important side chains, peptide superagonists, and new data on pseudopeptide modification of the N- and C-terminal regions. Members of these peptide families have been associated with a variety of physiological activities such as myotropism, pheromonotropism, diapause induction, and diuresis in a number of insects. Spectroscopic data coupled with computer molecular dynamics/graphics studies on conformationally restricted analogs of insect neuropeptides reveal information on the active conformation adopted at the receptor site. Routes to development of peptide-mimetics from neuropeptide templates are discussed.

A bifunctional heterodimeric insect neuropeptide analog.

The synthesis and biological activity of a bifunctional, heterodimeric insect neuropeptide analog are described. The heterodimer is composed of the C-terminal pentapeptide active core regions of the leucokinin/achetakinin and pyrokinin neuropeptide families linked via their N-terminal amino groups with a succinyl diacid moiety. Members of the leucokinin/achetakinin family can induce fluid secretion in malpighian tubules of the house cricket, Acheta domesticus, whereas the pyrokinins demonstrate activity in a cricket oviduct myotropic bioassay. No cross-activity is observed for the two neuropeptide families in these bioassays. However, the heterodimer elicits responses in both Acheta bioassays. Such a bifunctional analog may in future serve as a template for the design of stable, bifunctional pest insect control agents of greater efficiency.

An active pseudopeptide analog of the leucokinin insect neuropeptide family.

A pseudopeptide analog of the active core of the leucokinin insect neuropeptide family was synthesized and found to retain myotropic activity. No reports of active pseudopeptide analogs of an insect or other invertebrate neuropeptide have previously appeared in the literature. The pseudopeptide (Phe psi [CH2-NH] Phe-Ser-Trp-Gly-NH2) contains a reduced-amide linkage between the two N-terminal Phe residues. Unlike its amide-bond containing counterpart, the activity of the pseudopeptide was not destroyed upon exposure to aminopeptidase M.

Heparin dosing and monitoring for cardiopulmonary bypass. A comparison of techniques with measurement of subclinical plasma coagulation.

Subclinical plasma coagulation during cardiopulmonary bypass has been associated with marked platelet and clotting factor consumption in monkeys. To better define subclinical coagulation in man, we measured plasma fibrinopeptide A concentrations before, during, and after cardiopulmonary bypass. Patients were assigned to one of three groups of heparin management: group 1 (n = 10)--initial heparin dose 300 IU/kg, with supplemental heparin if the activated coagulation time fell below 400 seconds; group 2 (n = 6)--initial heparin dose 250 IU/kg, with supplemental heparin if activated coagulation time was less than 400 seconds; and group 3 (n = 5)--initial heparin dose 350 to 400 IU/kg, with supplemental heparin if whole blood heparin concentration was less than or equal to 4.1 IU/ml. Activated coagulation time and heparin concentration were measured every 30 minutes during cardiopulmonary bypass, and fibrinopeptide A was measured at hypothermia, normothermia, and whenever activated coagulation time was less than 400 seconds. Quantitative and qualitative blood clotting competence was assessed after cardiopulmonary bypass, including mediastinal drainage for the first 24 hours. Fibrinopeptide A values were markedly elevated during cardiopulmonary bypass but were well below the levels present before and after cardiopulmonary bypass. Fibrinopeptide A correlated inversely with heparin concentration during cardiopulmonary bypass (r = -0.46, p = 0.03), but higher fibrinopeptide A levels during cardiopulmonary bypass did not correlate with post-cardiopulmonary bypass coagulopathy. Group 3 patients received the highest heparin doses (p less than 0.05) and had the greatest postoperative blood loss (p less than 0.05). Protamine dose and heparin concentration during cardiopulmonary bypass correlated best with postoperative mediastinal drainage. Our findings support the following conclusions: (1) compensated subclinical plasma coagulation activity occurs during cardiopulmonary bypass despite activated coagulation time greater than 400 seconds or heparin concentration greater than or equal to 4.1 IU/ml; (2) post-cardiopulmonary bypass mediastinal drainage correlates strongly with increased heparin concentration during cardiopulmonary bypass (p less than 0.05) and protamine dose (p less than 0.05); and (3) during cardiopulmonary bypass at both normothermia and hypothermia, activated coagulation times greater than 350 seconds result in acceptable fibrinopeptide A levels and post-cardiopulmonary bypass blood clotting.

Structure-activity relationships for myotropic activity of the gastrin/cholecystokinin-like insect sulfakinins.

The sulfakinins constitute a family of real and putative peptide sequences characterized from the cockroach Leucophaea maderae (leucosulfakinin subfamily) and fruitfly Drosophila melanogaster (drosulfakinin subfamily) with homology to the sulfated mammalian hormones gastrin II and cholecystokinin (CCK). The leucosulfakinin (LSK) subfamily of neuropeptides stimulate contractions of the isolated cockroach hindgut. In this paper, we have ascertained some of the primary structural requirements of the sulfakinins for myotropic (muscle-contracting) activity. The myotropic "active core" of this family has been determined to be the C-terminal hexapeptide, though the C-terminal octapeptide (Glu-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2) is required for full activity. The LSKs demonstrate considerable tolerance to Ala substitution in positions 7 and 9 within the active core without complete loss of activity. Conversely, Ala substitution in positions 8, 10 and 11 led to inactive compounds. Basicity is a critical feature of LSK position 10, while aromatic character is an important characteristic for positions 8 and 11 for myotropic activity. Only trace activity could be observed upon replacement of the Tyr(SO3H) residue in LSK-position 6 with a Ser(SO3H). One analog ([3MeHis8] LSK) proved more active as a contractile stimulant than the natural product, while another ([7-11,Tyr(SO3H)7] LSK), conversely, demonstrated inhibition of spontaneous contractions of the cockroach hindgut.

Evidence for similarities and differences in the biosynthesis of fungal sterols.

The sterol composition of two ascomycetous fungi, Saccharomyces cerevisiae and Gibberella fujikuroi, was examined by chromatographic (TLC, GLC, and HPLC) and spectral (MS and 1H-NMR) methods. Of notable importance was that both fungi produced cholesterol and a homologous series of long chain fatty alcohols (C22 to C30). In addition to ergosterol two novel sterols, ergosta-5,7, 9(11), 22-tetraenol and ergosterol endoperoxide, were isolated as minor compounds in growth-arrested cultures of yeast and in mycelia of G. fujikuroi. 24-Ethylidenelanosterol was also detected in mycelia of G. fujikuroi. A shift in sterol biosynthesis was observed by treatment with 24 (RS), 25-epiminolanosterol (an inhibitor of the S-adenosylmethionine C-24 transferase) and by monitoring the sterol composition at various stages of development. The results are interpreted to imply that the genes for 24-desalkyl, e.g., cholesterol, and 24-alkyl sterols, e.g., 24 beta- methyl cholesterol and 24-ethyl cholesterol, are distributed (but not always expressed) generally throughout the fungi but the occurrence of one or another compounds is influenced by the fitness (structure and amount) for specific sterols to act functionally during fungal ontogeny; sterol fitness is coordinated with Darwinian selection pressures.

Effects of nimodipine on the production of thromboxane A2 following total global cerebral ischemia.

To clarify the contribution of vasoconstrictor prostaglandins to the hypoperfusion state typically following total global cerebral ischemia, 14 mongrel dogs were subjected to 11 minutes of global cerebral ischemia. They were then randomly assigned to receive either no treatment or an intravenous bolus of the calcium channel blocker nimodipine, 10 micrograms/kg, 15 minutes after ischemia followed by a continuous infusion of nimodipine, 1.0 micrograms/kg/min. Thromboxane (Tx) A2 production, as measured by cerebral venous levels of TxB2 (the stable metabolite of TxA2) increased similarly in the two groups. In contrast to previous studies, mean postischemic cerebral blood flow did not increase sufficiently in the nimodipine-treated group to achieve statistical significance. These data suggest that the improved neurological outcome associated with nimodipine treatment following global cerebral ischemia does not relate to reduced levels of the prostaglandin precursor arachidonate.

Theophylline effect on the cerebral blood flow response to hypoxemia.

Cerebral oxygen delivery (CO2D) remains nearly constant over a wide range of cerebral perfusion pressure and arterial oxygen content. In response to a decrease in arterial oxygen content secondary to hypoxemia, cerebral blood flow (CBF) increases, a response likely mediated by the release of adenosine. We studied the effect of theophylline, a potent adenosine antagonist, on CBF and cerebral oxygen delivery (CO2D) during hypoxemia in five healthy adult male volunteers. The CBF was measured using 133Xe clearance under conditions of (1) normoxemia (O2 saturation greater than 95 percent); (2) hypoxemia (O2 saturation = 80 percent); (3) normoxemia following aminophylline (the ethylene diamine salt of theophylline) 6 mg/kg intravenously; and (4) hypoxemia following aminophylline. Aminophylline decreased CBF and CO2D during both normoxemia and hypoxemia, but did not prevent the increase in CBF accompanying hypoxemia, suggesting that the increase in CBF in response to hypoxemia may not be mediated by adenosine or that customary doses of aminophylline are insufficient to inhibit adenosine-mediated cerebral vasodilation in response to hypoxemia. The significant decrease in CBF and CO2D observed following aminophylline is potentially clinically important and should be considered in the selection of bronchodilator therapy.

Structural aspects of gastrin/CCK-like insect leucosulfakinins and FMRF-amide.

The leucosulfakinins (LSKs), isolated from head extracts of the cockroach Leucophaea maderae, are sulfated neuropeptides with homology to gastrin and cholecystokinin. The undecapeptide LSK and decapeptide LSK-II stimulate contractions of the isolated cockroach hindgut. Several structural aspects of the two gastrin/CCK-like insect leucosulfakinins (LSKs) and their relation to FMRF-amide are discussed. Replacement of the oxidation sensitive Met residue with isosteric norleucine leads to an analog with retention of biological activity. The Arg residue of the LSKs is critical for cockroach hindgut contractile stimulatory activity, as its introduction into gastrin II transforms the inactive peptide into an active analog. As demonstrated by the equipotent [His14,Arg16]gastrin II, the His8 and Asp5 residues of LSK are not critical for activity. The common C-terminal tetrapeptide of the LSKs ([8-11]LSK) is inactive. Taken together with a comparison of the two LSK structures, the data suggest that the LSK active core resides between [8-11]LSK and [4-11]LSK. This is confirmed by considerable activity displayed by the sulfate analog of LSK-II, which contains an extra sulfate group on the Ser2 residue in the N-terminal region. Homology between the LSKs and molluscan cardioacceleratory and rectum contractile neuropeptide FMRF-amide and Met-enkephalin-Arg6-Phe7 is discussed. The insect LSKs may represent a molecular evolutionary link between the vertebrate gastrin/CCK family and this mammalian enkephalin.

Formation of cyclic adducts of deoxyguanosine with the aldehydes trans-4-hydroxy-2-hexenal and trans-4-hydroxy-2-nonenal in vitro.

trans-4-Hydroxy-2-hexenal (t-4HH), a reactive metabolite isolated from the pyrrolizidine alkaloid senecionine, and trans-4-hydroxy-2-nonenal (t-4HN), a product of lipid peroxidation, reacted nonenzymatically with deoxyguanosine at pH 7.4 at 37 degrees C in vitro with each compound yielding two pairs of diastereomeric adducts. Adducts were isolated using reverse phase high-performance liquid chromatography and were characterized by their mass spectra and proton magnetic resonance spectra. Adducts 1 and 2 from t-4HH were assigned the structures 3-(2-deoxy-beta-D-erythro-pentofuranosyl)-5,6,7,8-tetrahydro-8R-hydroxy- 6S[1- (R and S)hydroxypropyl]pyramido[1,2-a]purine-10-(3H)one and Adducts 3 and 4 were assigned the structures 3-(2-deoxy-beta-D-erythro-pentofuranosyl)-5,6,7,8-tetrahydro-8S-hydroxy- 6R-[1- (R and S)hydroxypropyl]pyramido[1,2-a]purine-10-(3H)one. Similar 6-hydroxyhexyl adducts were isolated in the reaction of deoxyguanosine with t-4HN. The reactions appear to involve Michael additions of the N2 amino group of deoxyguanosine followed by cyclization at the 1-N site. This reaction mechanism is similar to that reported for deoxyguanosine adduct formation with the nonhydroxylated alpha, beta-unsaturated aldehydes crotonaldehyde and acrolein. Total adduct formations following 16-h incubations were 0.91% for t-4HH and 0.85% for t-4HN. These results demonstrate that t-4HH and t-4HN possess the ability to alkylate deoxyguanosine in vitro and suggest possible mechanisms for 4-hydroxyalkenal and pyrrolizidine alkaloid genotoxicity.

Leucosulfakinin, a sulfated insect neuropeptide with homology to gastrin and cholecystokinin.

A sulfated, myotropic neuropeptide termed leucosulfakinin (Glu-Gln-Phe-Glu-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2) was isolated from head extracts of the cockroach Leucophaea maderae. The peptide exhibits sequence homology with the hormonally active portion of the vertebrate hormones human gastrin II and cholecystokinin, suggesting that these peptides are evolutionarily related. Six of the 11 amino acid residues (55 percent) are identical to those in gastrin II. In addition, the intestinal myotropic action of leucosulfakinin is analogous to that of gastrin.

Leucosulfakinin-II, a blocked sulfated insect neuropeptide with homology to cholecystokinin and gastrin.

A sulfated neuropeptide [pGlu-Ser-Asp-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2], with a blocked N-terminus and related to the undecapeptide leucosulfakinin, has been isolated from head extracts of the cockroach, Leucophaea maderae. It exhibits sequence homology with the hormonally-active portion of vertebrate hormones cholecystokinin, human gastrin II and caerulin. This peptide, termed leucosulfakinin-II, shares a common C-terminal heptapeptide fragment with leucosulfakinin and a comparison of the two sequences provides an assessment of the importance of the constituent amino acids to biological activity. Leucosulfakinin-II shows a greater resemblance to cholecystokinin than does leucosulfakinin. Leucosulfakinin-II and leucosulfakinin are the only two reported invertebrate sulfated neuropeptides. As with leucosulfakinin, the intestinal myotropic activity of leucosulfakinin-II is analogous to that of gastrin and cholecystokinin. The sequence homology between the leucosulfakinins and the vertebrate hormones, as well as their analogous myotropic activity, suggest that gastrin/cholecystokinin-like neuropeptides are not confined to vertebrates, but also occur in invertebrates.

trans-4-Hydroxy-2-hexenal: a reactive metabolite from the macrocyclic pyrrolizidine alkaloid senecionine.

The toxicity of macrocyclic pyrrolizidine alkaloids in the livers of man and animals has been attributed to the formation of reactive pyrroles from dihydropyrrolizines. Now a novel metabolite, trans-4-hydroxy-2-hexenal, has been isolated from the macrocyclic pyrrolizidine alkaloid senecionine, in an in vitro hepatic microsomal system. Other alkenals such as trans-4-hydroxy-2-nonenal have previously been isolated from microsomal systems when treated with halogenated hydrocarbons or subjected to lipid peroxidation. The in vivo pathology caused by trans-4-hydroxy-2-hexenal appears to be identical to that previously attributed to reactive pyrroles. There are similarities between the toxic effects of this alkenal and those of centrilobular hepatotoxins such as CCl4 and other alkenals formed during lipid peroxidation.

Two dihydropyrrolizine alkaloid metabolites isolated from mouse hepatic microsomes in vitro.

The in vitro mouse hepatic microsomal metabolism of the macrocyclic pyrrolizidine alkaloid senecionine was studied for additional metabolites. Using previously developed HPLC systems plus a preparative system, two additional dihydropyrrolizine metabolites have been identified from the microsomal enzyme system of mice. The metabolites 1-hydroxymethyl-7-methoxy-6,7-dihydro-5H-pyrrolizine (methoxydehydroretronecine) and 1-formyl-7-hydroxy-6,7-dihydro-5H-pyrrolizine (hydroxydanaidal) have not been heretofore isolated from mouse microsomal enzyme systems. The metabolite dehydroretronecine which had previously been isolated from rat hepatic microsomes, was not detected while senecic acid, 19-hydroxysenecionine, and senecionine N-oxide were again present.