Chaotic hemodynamic during oscillated blood flow

A vibrating flow pump (VFP), which can generate oscillated blood flow (10-50 Hz/min), has been developed by our team for the artificial heart system. However, the flow pattern of this pump was different from that of the natural heart; therefore, it is important to analyze the effect of this oscillated blood flow on the circulatory regulatory system. To analyze the hemodynamics of high frequency oscillated blood flow as an entity, (not decomposed), nonlinear mathematical techniques were utilized. VFPs were implanted between the left atrium in animal experiments using adult goats. After the implantation procedure, the ascending aorta was clamped to constitute the complete left heart circulation with VFP. Using a nonlinear mathematical technique, an arterial blood pressure waveform was embedded into four-dimensional phase space and projected into three-dimensional phase space. The Lyapunov numerical method was used as an adjunct to graphic analysis of the state space. Phase portrait of the attractor showed a high dimension complex structure, suggesting deterministic chaos during natural circulation. However, phase portrait of the hemodynamics during oscillated blood flow showed a single circle with banding and a forbidden zone, similar to a limit-cycle attractor, suggesting a lower dimensional dynamic system. Positive Lyapunov exponent during oscillated blood flow suggests the existence of lower dimensional chaotic dynamics. These results suggest that the circulatory regulatory system during oscillated blood flow may be a lower dimensional homeochaotic state; thus, hemodynamic parameters must be carefully regulated when unexpected external stimuli are present.

Study on pulmonary delivery of salmon calcitonin in rats: effects of protease inhibitors and absorption enhancers

Effects of protease inhibitors and absorption enhancers on the absorption of salmon calcitonin (sCT) were evaluated after intratracheal coadministration to rats using the plasma Ca level as an index. Remarkable absorption enhancement could be attained with unsaturated fatty acids such as oleic acid and polyoxyethylene oleyl ether (absorption enhancers) and with chymostatin, bacitracin, potato carboxypeptidase inhibitor and phosphoramidon (protease inhibitors). sCT degrading enzymes had four times higher activity per total protein in membrane fraction of lung homogenates than the activity in cytosol fraction. These enzymes are thought to be serine proteases and metalloenzymes from the in vitro action profile of protease inhibitors. A good correlation between the in vitro activity of protease inhibitors and the in vivo enhancing effect on sCT activity suggested that membrane enzymes are responsible for the inactivation of sCT. Metabolic degradation and low permeability of sCT may be possible barriers to the absorption of sCT.

[To avoid complications during laparoscopic cholecystectomy]

Laparoscopic cholecystectomy is now becoming a safe procedure for the benign cholecystic diseases. But the differences, for example in the method of access to peritoneal cavity, visual field, and tools, between laparoscopic surgery and open surgery results in different complications. The purpose of this paper is to discuss how to avoid complications during laparoscopic cholecystectomy. A hundred consecutive patients were expected to receive an elective laparoscopic cholecystectomy from April 1991 to November 1992 in our clinic. Two patients were converted to open cholecystectomy. The reasons for conversion were uncontrollable bleeding from cystic artery and common-bile duct injury. Two other patients were obliged to undergo laparotomy due to post-operative bile leakage. Arterial bleeding from abdominal wall caused by inserting trocar was experienced in one case. Improvement of the equipment and surgical technique have got rid of these complications. We think it is still necessary to do intra-operative examinations such as cholangiography or ultrasonography. The previous two cases with complication of biliary injury underwent laparoscopic cholecystectomy without intraoperative examinations. We could have avoided these complications if intraoperative examinations were used. To prevent the complication of bleeding from abdominal wall, we have been carrying out a unique method. After the introduction of these procedures, we have never experienced any of these complications.

Predisposing factors in fixation failure of femoral prostheses following primary Charnley low friction arthroplasty. A 10- to 20-year followup study

To identify factors affecting radiologically detected loosening of the Charnley femoral prosthesis, 326 femoral prostheses with 10- to 20-year followup were studied. After observation of postoperative radiological changes, the criteria for fixation failure detected radiologically, of femoral prostheses were defined as progression or accompanying occurrences of subsidence, demarcation, separation of the prosthesis from cement, cement fracture, or endosteal cavitation. Sixteen femoral prostheses (4.9%) developed radiologically detected fixation failure. Male gender, low canal flare index, low femoral score, large medullary canal width, low implant (cement and stem)/canal ratio, low stem/canal ratio, and varus orientation of the stem affected fixation failure. Inadequate cementing techniques such as low implant/canal and stem/canal ratios and varus stem orientation might be within the surgeon's control and should be avoided. An unfavorable canal geometry (stovepipe canal) and osteopenia of the femur, indicated by a low femoral score, are risk factors that might be out of the surgeon's control, and require future research.

Risk factors affecting radiological failure of the socket in primary Charnley low friction arthroplasty. A 10- to 20-year followup study

To identify the factors affecting Hodgkinson Type 3 or 4 radiological demarcation (presence of complete demarcation or migration, respectively) of the Charnley socket, 328 sockets with 10- to 20-year followup were studied. Fifty-five sockets (16.8%) developed Type 3 or 4 demarcation. In the osteoarthrosis group (237 sockets), removal of eburnated bone at the acetabular roof, the presence of large acetabular angles before and after surgery, and high placement of the socket were related to development of Type 3 or 4 demarcation. In the rheumatoid group (32 sockets), young patient age predisposed the socket to Type 3 or 4 demarcation. Rapid polyethylene wear, correlated with young age, male gender, and thin cement mantle in Zones I and II, was another important factor related to Type 3 or 4 demarcation in both groups and in the entire series. These risk factors should be taken into account when assessing the indications for arthroplasty, when performing arthroplasty, and when educating the patient.

Reduction of visual P300 during transient global amnesia

Transient global amnesia (TGA) is a syndrome of selective loss of recent memory without other neurological deficits. Auditory and visual P300s were recorded during and after TGA to investigate the contribution of the short-term memory system to P300 generation. The auditory P300 during TGA was comparable to that recorded 1 week and 9 months after TGA. In contrast to the auditory modality, the visual target P300 was reduced in amplitude during TGA and at 1 week after the attack. The P300 to novel visual stimuli was also reduced during TGA. Both target and novelty visual P300 recovered by 9 months after TGA. The results support the notion that the neuronal networks responsible for P300 generation are modality dependent and that brain structures perfused by the posterior circulation are involved in visual P300 generation.

Carotid arterial impedance during oscillated blood flow

Blood perfusion of systemic circulation is influenced by the physical characteristics of artery. Several investigations proposed that the physical parameters of vessels are determined by neurological factors, hormonal factors, and physical properties of arteries among others. In this study, arterial impedance was estimated because it may express the condition of vessels. To examine the change of arterial impedance according to the blood flow pattern, the typical sine wave blood flow (oscillated flow) was used during total cardiopulmonary bypass (CPB) because it is considered the most simple pulsatile flow. CPB using oscillated blood flow was performed in acute experiments on adult goats. Total systemic flow was controlled to remain at approximately 80 ml/min. Carotid arterial flow, aortic pressure, central venous pressure, and systemic flow were measured. Total peripheral resistance, carotid arterial resistance, systemic impedance, and carotid arterial impedance were calculated to evaluate blood flow distribution during CPB. This study suggested that the parameters of carotid arterial blood flow changed according to the change of flow frequency during oscillated blood flow. This change may occur because arterial impedance was influenced by flow frequency; therefore, the blood flow of the carotid artery was significantly changed according to the change of the frequency component of blood flow.

Decreased synaptic density in aged brains and its prevention by rearing under enriched environment as revealed by synaptophysin contents

Changes in synaptic density in various brain regions were assessed among different age groups of rats maintained in ordinary small cages, as determined by synaptophysin assay. The synaptophysin content in hippocampus decreases as early as in the adult stage. The most remarkable decrement occurs in occipital cortex. In other regions, synaptophysin contents decrease in senescence to 60-77% of the respective peak values during young and adult stages. The other rat group reared under enriched environment in a large cage until 30 months of age was examined for synaptic density, and was revealed to maintain the similar levels as in young, or even higher levels in frontal, temporal, entorhinal cortices and hippocampus. These results indicate that the synaptic density in cerebrum decreases in senescence and this decrease can be prevented by rearing under enriched environment.

Intrahepatic peribiliary vascular plexus in various hepatobiliary diseases: a histological survey

The peribiliary vascular plexus (PVP) plays an important role in the pathophysiology of the biliary tree. We histologically examined vascular endothelial cells of the intrahepatic PVP in various hepatobiliary diseases by immunohistochemistry and lectin histochemistry with antibodies to factor VIII-related antigens (F-VIII-R-Ag) and Ulex europaeus agglutinin I (UEA-I). The PVP around the intrahepatic large bile ducts (LBDs) and septal bile ducts (SBDs) in normal livers consists of three layers: inner layer vessels immediately adjacent to the epithelium, intermediate layer vessels within the ductal wall, and outer layer vessels outside the ductal wall. In some bile ducts that show active inflammation in hepatolithiasis, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and extrahepatic biliary obstruction (EBO), vessels in the intermediate layer and, to a lesser degree, in the inner layer, are increased in number. In sclerotic bile ducts of PSC, EBO, and hepatolithiasis, the number of inner and intermediate layer vessels are markedly and variably reduced, respectively. In liver cirrhosis or chronic advanced liver diseases, the vessels in all three layers, particularly those in the outer layer, are increased in number and dilated, probably reflecting intrahepatic microcirculatory disturbance. The PVP showed several types of numerical and luminal changes, each of which may be related to disease processes in the intrahepatic biliary tree as well as to intrahepatic microcirculatory disturbance.

Interleukin-11

Interleukin-11 (IL-11), a stromal cell-derived cytokine, has been known to act widely in hematopoietic and non-hematopoietic systems. IL-11 supports the growth of certain types of plasmacytoma and hybridoma cells, acts with interleukin-3 (IL-3) in shortening the Go period of early progenitors. IL-11 supports megakaryocyte colony formation and maturation, and acts as an autocrine growth factor in megakaryoblastic cell lines. In addition, IL-11 stimulates erythrocytopoiesis, enhances antigen-specific antibody responses, induces the synthesis of acute phase proteins, inhibits lipoprotein lipase activity and adipocyte differentiation, and promotes neuronal development. Administration of rhIL-11 to mice resulted in an increase of neutrophils and platelets. The human IL-11 gene is localized at 19q13.3-13.4, and codes 199 amino acids and 23 kDa with no N glycosylation. Its receptor and signal transduction share partially those of interleukin-6 (IL-6). Further analysis of its role in normal and pathological state is necessary to determine the exact function and its application for clinical uses.

Assembly of synthetic cellulose I

Cellulose microfibrils with an electron diffraction pattern characteristic of crystalline native cellulose I have been assembled abiotically by means of a cellulase-catalyzed polymerization of beta-cellobiosyl fluoride substrate monomer in acetonitrile/acetate buffer. Substantial purification of the Trichoderma viride cellulase enzyme was found to be essential for the formation of the synthetic cellulose I allomorph. Assembly of synthetic cellulose I appears to be a result of a micellar aggregation of the partially purified enzyme and the substrate in an organic/aqueous solvent system favoring the alignment of glucan chains with the same polarity and extended chain conformation, resulting in crystallization to form the metastable cellulose I allomorph.

Elevated tyrosine hydroxylase mRNA levels in the adrenal medulla of spontaneously hypertensive rats

We investigated the expression of tyrosine hydroxylase (TH) mRNA and its activity in the adrenal medulla of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The TH mRNA levels were determined by Northern blot and dot blot analyses. The TH activity and the expression of TH mRNA in the adrenal medulla of SHR were significantly higher than those of WKY (P < 0.01). These results suggested that the hypertension of SHR may be related to the high activity of TH due to the high level of TH mRNA, which increases epinephrine and norepinephrine levels in the adrenal medulla.

Accentuated temporal line on the frontal skull radiograph: a sign of hyperparathyroidism

PURPOSE

To determine the importance of a temporal line (the marginal line for the attachment of the temporal muscle to the skull) that is accentuated on frontal skull radiographs of hyperparathyroid patients owing to subligamentous bone resorption under the temporal muscle.

MATERIALS AND METHODS

Radiographs from skeletal surveys of 134 surgically treated patients with primary (n = 102) or secondary (n = 32) hyperparathyroidism (HPT) and frontal skull radiographs of 63 age-matched control patients were reviewed.

RESULTS

An accentuated temporal line was the most frequent finding (29.4% of cases) in primary HPT, followed by subperiosteal bone resorption in the hand (8.6%), salt-and-pepper appearance of the skull (3.5%), and rugger-jersey spine (1.1%). In secondary HPT, an accentuated temporal line became less obvious as subperiosteal bone resorption advanced. This finding was not seen in the control group.

CONCLUSION

An accentuated temporal line is another radiographic indication of bone resorption in HPT.

Effects of interleukin-6 on hematopoiesis in allogeneic and syngeneic bone marrow chimeras

Effects of interleukin-6 (IL-6) on hematopoietic progenitor cells were analyzed in murine bone marrow chimeras. When IL-6 was injected into syngeneic [C3H/He-->C3H/He] bone marrow chimeras from day 1 to day 12, the numbers of highly proliferative potential colony-forming units (CFU-HPP) or colony-forming units mix (CFU-Mix) in spleen cells and bone marrow cells increased on day 14 although there was a marked increase in spleen cells but not in bone marrow cells on day 21. The numbers of CFU-HPP increased in spleen cells from allogeneic [BALB/c-->C3H/He] bone marrow chimeras injected with IL-6 on days 14 and 21. In syngeneic bone marrow chimeras, the numbers of colony-forming units granulocyte/macrophage (CFU-GM) and burst colony-forming units (BFU-E) increased similarly to those of CFU-HPP and CFU-Mix on day 14. On day 21, these were mainly increased in spleen cells. In allogeneic bone marrow chimeras, IL-6 decreased the numbers of CFU-GM and BFU-Mix dose-dependently on day 14. Only 10 micrograms of IL-6 increased the numbers of CFU-GM and BFU-E on day 21. In our previous work, we showed that platelet counts increased on day 14 in syngeneic bone marrow chimeras injected with IL-6, whereas platelet and leukocyte counts increased on days 14 and 24 in allogeneic bone marrow chimeras injected with IL-6, correlating inversely with the numbers of hematopoietic progenitor cells. Overall, primitive hematopoietic progenitors (i.e., CFU-HPP and CFU-Mix) existed primarily in spleen cells of allogeneic bone marrow chimeras on day 14, whereas those in spleen cells of syngeneic bone marrow chimeras were found on day 21. These findings indicate that the effect of IL-6 on hematopoiesis in allogeneic bone marrow chimeras is completely different from that in syngeneic bone marrow chimeras, probably via graft-versus-host reaction (GVHR) but not GVH disease (GVHD).

Trigeminal sensory innervation on perforators of the circle of Willis in rabbits by wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing

Distribution patterns of sensory innervation from the trigeminal ganglion to the perforators of the circle of Willis in rabbits were investigated by wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) anterograde tracing. Twenty Japanese white rabbits were anesthetized by inhaling 1% halothane. Using a microsurgical technique, 4 microliters of 2% WGA-HRP in 1 M KCl solution, colored with brilliant blue, was micro-injected into the medial part of the left trigeminal ganglion in 14 animals with a pressure injection system. Another six served as controls to exclude the possibility of labeling non-trigeminal axons. Forty-eight hours later, the perforators in the cisternal and intracerebral segments along with their parent arteries were dissected from the brain according to Dacey's dissecting technique after transcardial perfusion, reacted with the 3,3',5,5'-tetramethyl benzidine method of Mesulam. The results revealed that sensory nerves on the perforators of the circle of Willis were less densely innervated than those on their parent arteries due to the difference in diameter. The posteromedial perforating arteries arising from the P1 segment of the posterior cerebral artery to the tegmentum, posteroventral thalamus and posterior hypothalamus were more prominently and consistently innervated than other perforators. The sensory fibers were seen on the cisternal segment of the perforating arteries. A parallel or twisted pattern was found in the perforators less than 100 microns in diameter, while a meshwork pattern was visualized in the proximal part of some bigger ones. Fine sensory fibers could be traced on the perforators as small as 40 microns in diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of the binding and functional properties of alpha-1 adrenoceptors and area density of smooth muscle in the human, canine and rat prostates

The present study was designed to compare the binding and functional properties of alpha-1 adrenoceptors and the area density of smooth muscle in the human, canine and rat prostates. Chloroethylclonidine (CEC)-sensitive and -insensitive alpha-1 adrenoceptors were characterized on slide-mounted prostatic tissue sections using the ligand [3H]prazosin. The mean equilibrium dissociation constants (Kd) for [3H]prazosin binding sites were not significantly different among the three different species. The densities (Bmax) of CEC insensitive [3H]prazosin binding sites in the human, canine and rat prostates were 1.71 +/- 0.32, 0.35 +/- 0.04 and 0.84 +/- 0.11 fmol/mg of wet weight, respectively. The Bmax of CEC-sensitive [3H]prazosin binding sites in the human, canine and rat prostates were 1.32 +/- 0.83, 0.44 +/- 0.11 and 0.25 +/- 0.10 fmol/mg of wet weight, respectively. The contractile response elicited by the rat prostate in the presence of phenylephrine was consistently negligible. The mean maximal force after phenylephrine challenge (phenylephrine Emax) in the human and canine prostates were 0.125 +/- 0.025 g of force/mm2 cross-sectional area and 0.096 +/- 0.014 g of force/mm2 cross-sectional area, respectively. CEC inactivated 80 and 53% of the phenylephrine contractile response in man and dog, respectively. The mean percentage of area densities of smooth muscle in the human, canine and rat prostates were 38.8, 12.9 and < 1%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative CT scan findings during resection of glial tumours

Intraoperative computerized tomographic (CT) scan findings in two cases during resection of glial tumor are described. These intraoperative CT images were obtained by an exclusively developed operating CT scanner system for use in the operating room. Repeated intraoperative CT scans taken during tumor removal showed shift of the brain including central structures and displacement of the cortical subarachnoid space in both cases. With contrast medium, the edge of the surrounding brain after resection was enhanced and a round enhanced area was observed in distant white matter. The distant enhancement, which we call 'remote enhancement', probably suggests damage to the blood-brain barrier due to surgical manoeuvre.

Hemifacial spasm and cerebellopontine angle epidermoid: case report and review

A case with hemifacial spasm with tinnitus due to right cerebellopontine angle epidermoid is reported. The tumour was supposed to have caused the displacement of the part of anterior inferior cerebellar artery in the vicinity of the root exit zone of the ipsilateral facial nerve. Near total removal of the tumour along with microvascular decompression was done and the patient was completely relieved of his symptoms. The incidence of hemifacial spasm due to cerebellopontine angle epidermoid is extremely low. The cause of such an association is discussed and relevant literature is reviewed.

[Changes in fatty acid composition, platelet aggregability and RBC function in elderly subjects with administration of low-dose fish oil concentrate and comparison with younger subjects]

Anti-thrombotic and anti-atherogenic effects of eicosapentaenoic acid (EPA) through the modulation of various cell functions related to thrombogenesis have been reported recently. We previously reported that the administration of EPA at low doses could more effectively elevate the plasma EPA concentration in elderly subjects than in younger ones. Magnetic resonance imaging examination of the brain often reveals lacunar lesions in elderly subjects without any signs or symptoms of cerebrovascular diseases. In this study we clarified the effect of administration of low doses of fish oil concentrate on platelet and RBC function in elderly subjects, compared with younger subjects. Thirty six elderly subjects (mean age 78) without any signs or symptoms of cerebrovascular diseases, all receiving the same diet in the same lodging house for the aged, were divided into 3 groups. Different amounts of fish oil concentrate (0.25-0.5 g/day of EPA) were administered to the 3 groups, daily for more than 1 month. Changes of plasma fatty acid composition, platelet aggregability, whole blood viscosity and RBC deformability was examined before and after EPA administration. One month after EPA treatment, the plasma EPA content had increased dose dependently, with suppression of platelet aggregation and improvement of RBC function. In younger subjects receiving the same amount of EPA, the elevation of plasma EPA was less than that observed in the elderly. In summary, low dose EPA administration can improve the function of platelet and RBC to an anti-thrombotic state and would be useful to prevent the occurrence of cerebrovascular diseases in elderly subjects without any side effects.

[Allograft (homograft) valve surgery: current status in Japan]

The advance of cryopreservation techniques has dramatically increased the durability of human allograft valves, resulting in the wide-spread use of allograft valves in many western countries except Japan. The superiority of the allograft valve to other prosthetic valves has become apparent in some specific situations such as active endocarditis, small aortic root and hemorrhagic conditions. In this manuscript, we described the setting-up of the cryopreservation laboratory, quality control and the clinical use of allograft valves in our institute. The authors believe that surgeons should have an option of utilizing allograft valves in selected patients in Japan.

Recurrent Breast Cancer at 21 years after Resection Detected by Serum Tumor Markers and Manifested as Dermatomyositis

A 52-year-old Japanese woman developed dermatomyositis. She had undergone a standard radical mastectomy for left breast cancer 21 years earlier. Though no physical sign of recurrent breast cancer appeared clinically, levels of tumor markers were abnormally elevated. Therefore, tamoxifen and CAF therapy were given. Further, the clinical course of dermatomyositis almost paralleled the level of serum tumor markers and the clinical course of her recurrent breast cancer. These markers were useful for detecting the recurrence, following the metastatic disease, and monitoring her response to therapy.

In vivo effects of the immunosuppressant 15-deoxyspergualin on hematopoiesis in murine allogeneic bone marrow chimeras. Its thrombopoietic activity and reversal of adverse effects with granulocyte colony-stimulating factor and/or erythropoietin

When 15-deoxyspergualin (DSG), a potent immunosuppressant, was administered into [BALB/c-->C3H/He] bone marrow chimeras from day 14 to day 25, increased thrombopoiesis was induced on day 20 to day 33, accompanied by marked leukocytopenia and anemia. The mean platelet counts in DSG-treated and control [BALB/c-->C3H/He] bone marrow chimeras on day 25 were (114.1 +/- 0.5) x 10(4)/microliter versus (58.6 +/- 2.6) x 10(4)/microliter (1.9-fold increase). Colony-forming units-megakaryocyte (CFU-Meg) were not significantly increased in DSG-treated bone marrow chimeras. Colony-forming units-granulocyte/macrophage (CFU-GM) and burst-forming units-erythroid (BFU-E) were decreased during DSG-treatment whereas CFU-Mix colony formations were rather increased, and more primitive hematopoietic progenitor cells (highly proliferative potential colony-forming units [CFU-HPP]) were not decreased in the same time period. Since CFU-GM and BFU-E colony formations were increased immediately after the cessation of DSG treatment, followed by the rebound of leukocyte counts and the recovery of hemoglobin (Hb) levels, the leukocytopenia and anemia appeared to be induced by a cytostatic effect of DSG. The adverse effect of DSG was partly reversed by the simultaneous administration of granulocyte colony-stimulating factor (G-CSF) and/or erythropoietin (EPO), suggesting the need for the administration of these cytokines in the case of bone marrow transplants treated with DSG. Furthermore, it was of note that DSG modulated hematopoiesis and stimulated the production of thrombopoietin (TPO)-like cytokine(s) as well as interleukin-3 (IL-3).

Development-related and cell-type specific nuclear localization of annexin XI: immunolocalization analysis in rat tissues

Subcellular distribution of a novel annexin, annexin XI, was examined in rat tissues. As we have previously reported, annexin XI mainly localizes in nuclei of 3Y1, the rat embryonic fibroblast cell line; however, immunoperoxidase staining was not particularly nuclear in most of the tissues examined in adult rats. Nuclear localization of annexin XI was uncommon in adult rat tissues. By contrast, in the day-14 rat embryo, the undifferentiated mesenchymal cells were labeled mainly in the nuclei. The connective tissues of 18-day fetus, however, did not show predominantly nuclear staining any longer. In addition, the developing gray matter of the embryonic rat spinal cord exhibited primarily nuclear localization of annexin XI while the annexin XI immunoreactivity diminished and became absent from the nuclei in the adult spinal cord. On the other hand, the endodermal cells never displayed nuclear annexin XI at any developmental stages examined. All these findings suggested that subcellular localization of annexin XI is regulated depending on developmental stages and the cell types.

Application of pharmacokinetically guided dose escalation with respect to cell cycle phase specificity

BACKGROUND

In 1986, the concept of pharmacokinetically guided dose escalation (PGDE) was proposed to predict the maximum tolerated dose (MTD) of an antitumor drug in humans from animal data. We have previously shown that antitumor drugs can be classified into two types, depending on their cytotoxic mechanisms: type 1 drugs, which are cell cycle phase-nonspecific agents, i.e., area under the curve for drug concentration in the plasma versus time (AUC)-dependent drugs; and type 2 drugs, which are cell cycle phase-specific agents, i.e., those that are time dependent.

PURPOSE

The validity of the assumption that the AUC at the dose lethal for 10% of mice administered drug (LD10) is equal to the AUC at MTD for humans, the premise on which PGDE is based, was examined for type 1 and 2 drugs.

METHODS

Findings in the literature, including those of Collins and co-workers, were retrospectively analyzed. The human/mouse ratios for the AUC were compared with each other and with the human/mouse dose ratios, based on milligram per meter square of body surface area, the measurement currently used in clinical trials of antitumor drugs. For six of the type 1 drugs, the human/mouse ratio for the AUC of total drug (AUC) and that of unbound drug (AUCu), which has been considered a determinant of pharmacologic and toxicologic effects, were also compared.

RESULTS

There was an excellent correlation between log AUC at LD10 for mice and log AUC at MTD for humans for type 1 drugs (r = .898), but not for type 2 drugs (r = .677). For type 1 drugs, the correlation between mouse AUC at LD10 and human AUC at MTD was better for unbound drug (r = .961) than for total drug (r = .892).

CONCLUSIONS

PGDE is useful for type 1 drugs; differences in protein binding between species should, however, be considered when using this method.