Mechanical, structural, and morphological differences in the iliac arteries

Iliac arteries play a crucial role in peripheral blood circulation. They are susceptible to various diseases, including aneurysms and atherosclerosis. Structure, material properties, and biomechanical forces acting on different regions of the iliac vasculature may contribute to the localization and progression of these pathologies. We examined 33 arterial specimens from common iliac (CI), external iliac (EI), and internal iliac (II) arteries obtained from 11 human donors (62 ± 12 years). We conducted morphometric, mechanical, and structural analyses using planar biaxial tests, constitutive modeling, and bi-directional histology on transverse and axial sections. The iliac arteries exhibited increased tortuosity and varying disease distribution with age. CI and II arteries displayed non-uniform age-related disease progression around their circumference, while EI remained healthy even in older individuals. Trends in load-free and stress-free thickness varied along the iliac vasculature. Longitudinally, EI exhibited the highest compliance compared to other iliac vessels. In contrast, CI was stiffest longitudinally, and EI was the stiffest circumferentially. Material parameters for all iliac vessels are reported for four common constitutive relations. Elastin near the internal elastic lamina displayed greater waviness in EI and II compared to CI. Also, EI had the least glycosaminoglycans (GAGs) and the highest elastin content. Our findings highlight variations in the morphological, mechanical, and structural properties of iliac arteries along their length. This data can inform vascular disease development and computational studies, and guide the development of biomimetic repair materials and devices tailored to specific iliac locations, improving vascular repair strategies.

Variability in structure, morphology, and mechanical properties of the descending thoracic and infrarenal aorta around their circumference

Aortic diseases, such as aneurysms, atherosclerosis, and dissections, demonstrate a preferential development and progression around the aortic circumference, resulting in a highly heterogeneous disease state around the circumference. Differences in the aorta's structural composition and mechanical properties may be partly responsible for this phenomenon. Our goal in this study was to analyze the mechanical and structural properties of the human aorta at its lateral, anterior, posterior, and medial quadrants in two regions prone to circumferentially inhomogeneous diseases, descending Thoracic Aorta (TA) and Infrarenal Aorta (IFR). Human aortas were obtained from 10 donors (64 ± 11 years) and dissected from their loose surrounding tissue. Mechanical properties were determined in all four quadrants of TA and IFR using planar biaxial testing and fitted to three common constitutive models. The structure of tissues was assessed using Movat Pentachrome stained histology slides. We observed that the anterior quadrant exhibited the greatest thickness, followed by the lateral region, in both the TA and IFR. In TA, the posterior wall appeared as the stiffest location in most samples, while in IFR, the anterior wall was the stiffest. We observed a higher glycosaminoglycans content in the lateral and posterior regions of the IFR. We found elastin density to be similar in TA lateral, anterior, and posterior quadrants, while in IFR, the anterior region demonstrated the highest elastin density. Despite significant variations between subjects, this study highlights the distinct morphometrical, mechanical, and structural properties between the quadrants of both TA and IFR.

Adult xanthogranulomatous disease of the orbit and ocular adnexa: new immunohistochemical findings and clinical review

BACKGROUND/AIMS

Adult xanthogranulomatous disease involving the ocular tissues is rare and poorly understood. Adult onset xanthogranuloma (AOX), adult onset asthma and periocular xanthogranuloma (AAPOX), necrobiotic xanthogranuloma (NBX), and Erdheim-Chester disease (ECD) are the four syndromes within this disorder, which is diagnosed by characteristic histopathology. Experience with eight cases prompted a multi-institutional effort to study the histopathology, immunohistochemistry, clinical findings, and systemic associations in this disorder.

METHODS

22 cases, including histopathological slides, were compiled. Published reports were identified by an English language Medline search (1966-2005) and review of reference citations. Each case in this series and the literature was classified as one of four syndromes and then analysed for age onset, sex, skin xanthoma, orbital location, immune dysfunction, internal organ and bone lesions, treatment, and outcome. The histopathology in each of these cases was reviewed by two pathologists. Immunhistochemical stains (CD3, CD4, CD8, L26) were performed in 14 cases where unstained slides were available.

RESULTS

137 cases were compiled. There was no sex or age difference between syndromes. AOX, AAPOX, NBX affect the anterior orbit, ECD tends to be diffuse and intraconal. Skin lesions are found in all the syndromes. Immune dysfunction was noted in all cases of AAPOX and NBX; 11% of NBX and all ECD patients had internal organ disease. Treatment included surgery, corticosteroids, other chemotherapeutic agents, radiotherapy, and combinations of these. No AOX or AAPOX deaths occurred; 66% of ECD patients died. All 22 cases had xanthoma cells; most had Touton giant cells. Lymphocytes were present in all cases and occurred as aggregates (mostly in AAPOX) or diffuse populations mixed with fibroblasts (mostly in ECD). Immunohistochemistry revealed the majority of these to be CD8+. Necrosis was most marked in NBX.

CONCLUSION

Adult xanthogranuloma of the orbit is rare, making prospective evaluation or meta-analysis impossible. The best treatment is unknown but seems to be with multiagent chemotherapy guided by histopathological, immunohistochemical, and systemic findings.

Reversal of dysthyroid optic neuropathy following orbital fat decompression

AIMS

To document the successful treatment of five patients with dysthyroid optic neuropathy by orbital fat decompression instead of orbital bone decompression after failed medical therapy.

METHODS

Eight orbits of five patients with dysthyroid optic neuropathy were selected for orbital fat decompression as an alternative to bone removal decompression. Treatment with systemic corticosteroids and/or orbital radiotherapy was either unsuccessful or contraindicated in each case. All patients satisfied clinical indications for orbital bone decompression to reverse the optic neuropathy. High resolution computerised tomographic (CT) scans were performed in all cases and in each case showed signs of enlargement of the orbital fat compartment. As an alternative to bone decompression, orbital fat decompression was performed on all eight orbits.

RESULTS

Orbital fat decompression was performed on five patients (eight orbits) with optic neuropathy. Optic neuropathy was reversed in all cases. There were no cases of postoperative diplopia, enophthalmos, globe ptosis, or anaesthesia. All patients were followed for a minimum of 1 year.

CONCLUSIONS

In a subset of patients with an enlarged orbital fat compartment and in whom extraocular muscle enlargement is not the solitary cause of optic neuropathy, fat decompression is a surgical alternative to bony decompression.

Absence of seasonal variation in Graves disease

PURPOSE

To determine whether there is an identifiable pattern of seasonal variation in the onset of symptoms of orbitopathy and thyrotoxicosis in patients with Graves disease.

METHODS

This retrospective, noncomparative case series reviewed 305 randomly selected office records of patients referred to one author (M.K.) for evaluation of Graves orbitopathy between July 1990 and June 1998. All patients met inclusion criteria for the diagnosis of Graves orbitopathy. During initial evaluation for orbitopathy, patients identified the date of onset of orbital symptoms as well as the earliest date of either onset of thyroid symptoms or documented thyroid abnormality. Patients were excluded from analysis of seasonal variation if they could not recall the month of symptom onset or were euthyroid. The onset of orbital symptoms and identification of dysthyroid state were analyzed by calendar month and season. The chronological relationship of the development of orbital and thyroid symptoms was evaluated.

RESULTS

No significant seasonal variation appeared in the onset of orbital symptoms or identification of dysthyroidism. Out of 148 patients, 115 (78%) developed symptoms of orbital disease within 18 months of the identification of dysthyroidism. The most common presenting orbital symptoms were swelling of the lid or prominence of the globe.

CONCLUSIONS

This study fails to provide evidence for a seasonal influence on the incidence of Graves disease and the associated orbitopathy.

Management of conjunctival cicatrizing diseases and severe ocular surface dysfunction

Physical or chemical injuries, infections, immunologic oculocutaneous disorders, drugs, and various systemic disorders may cause scarring of the conjunctiva and disturbances of the ocular surface. Trichiasis, lid margin malposition, and dry eye may result in persistent ocular irritation. The cornea may be primarily or secondarily involved. If severe, disturbances of the ocular surface may lead to significant visual impairment. Thorough evaluation of patients and of the underlying disease process is required for optimal management. Treatment may be challenging and should be comprehensive, combining medical measures and surgical correction of structural changes. Suppression of exogenous irritants, treatment of dry eye, antiinflammatory therapy, and immunosuppressants are paramount to control the underlying disease and allow optimal surgical results. Surgical correction of trichiasis and lid margin malposition, conjunctival grafting, mucous membrane transplantation, limbal stem cell transplantation, amniotic membrane transplantation, and penetrating keratoplasty help reestablish a physiologic ocular surface. Severe cases may require keratoprosthetics for visual rehabilitation. Corneal ulceration or perforation requires prompt attention to maintain ocular integrity. Special measures should be considered for patients who require cataract or glaucoma surgery.

Magnetic resonance imaging of optic perineuritis

Optic perineuritis, an uncommon variant of orbital pseudotumor, may be clinically indistinguishable from retrobulbar optic neuritis. Because treatment and prognosis for these two entities are different, early diagnosis is important. We report a case of a 47 year-old woman with clinical findings suggestive of retrobulbar optic neuritis, but whose magnetic resonance images suggested optic perineuritis. A dramatic clinical response to oral corticosteroids was observed. Optic perineuritis should be considered in cases of presumed retrobulbar optic neuritis. MRI may differentiate these two entities in the acute stage, and should be considered before treatment is decided.

The role of postoperative irradiation in the management of sphenoid wing meningiomas. A preliminary report

PURPOSE

To determine whether postoperative radiation therapy decreases recurrence rates in subtotally excised and recurrent sphenoid wing meningiomas.

METHODS

Patients with primary subtotally excised and recurrent sphenoid wing meningiomas who underwent surgery between 1981 and 1994 (n = 105) were prospectively followed for recurrence. Postoperative radiation was not recommended in patients who had complete excision; therefore, their recurrence rates were not evaluated in this study. Patients with malignant meningiomas also were excluded from analysis. Recurrence was defined as evidence of tumor growth on neuroimaging with or without clinical symptoms.

RESULTS

Follow-up information was available for 86 patients; 69 had primary subtotally excised tumors and 17 had recurrent tumors. Follow-up information was unavailable in the remaining 19 patients. Tumor location and histopathology, type of surgery performed, and patient sex and age were similar in the irradiated and nonirradiated subgroups. Postoperative irradiation was delivered to 31 patients with primary tumors and 11 with recurrent tumors; none of these 42 patients had recurrence during a mean observation period of 4.2 and 3.5 years, respectively. The nonirradiated group consisted of 38 patients with primary tumors and 6 with recurrent tumors; 16 of 18 patients who had primary meningiomas had a recurrence and 5 of 6 who had recurrent tumors had another relapse (mean interval between resection and recurrence, 4.4 years and 14 months, respectively).

CONCLUSIONS

Postoperative radiation appeared to delay recurrence in subtotally excised and recurrent sphenoid wing meningiomas during the time frame of this study.

Varicella-zoster virus retrobulbar optic neuritis in a patient with human immunodeficiency virus

PURPOSE

To determine the cause of bilateral retrobulbar optic neuritis followed by progressive outer retinal necrosis in a patient with human immunodeficiency virus (HIV).

METHODS

Extensive ophthalmologic, neurologic, infectious disease, rheumatologic, and radiologic examinations were performed.

RESULTS

Cerebrospinal fluid samples taken after the onset of bilateral retrobulbar optic neuritis and before the development of clinical progressive outer retinal necrosis disclosed varicella-zoster virus from polymerase chain reaction and viral culture.

CONCLUSION

Ophthalmologists and neurologists should consider varicella-zoster virus optic neuritis as a potential precursor of progressive outer retinal necrosis and as a cause of retrobulbar optic neuritis in patients infected with HIV.

Prominent proptosis in childhood thyroid eye disease

BACKGROUND

Orbital signs and symptoms occur in approximately one half of children with Graves disease, but the symptoms are usually minor and limited to the eyelids. Prominent proptosis is uncommon in children with this disorder.

METHODS

Review of eight children with prominent proptosis associated with thyroid eye disease. Four patients were treated at the Children's Hospital of Philadelphia, the other four at the Columbia Presbyterian Medical Center.

RESULTS

At initial presentation, children ranged in age from 3 to 16 years. There were five girls and three boys. Seven of eight children had hyperthyroidism at ophthalmic presentation. Four patients had restrictive myopathy, and all of the seven patients who underwent neuroimaging had extraocular muscle enlargement. Five patients were treated with lubrication. Two underwent orbital fat decompression. One patient had thyroid eye disease and myasthenia gravis.

CONCLUSIONS

Proptosis in childhood thyroid eye disease usually is associated with a hyperthyroid state. The proptosis may be dramatic, but corneal exposure and restrictive myopathy are seen in only some of the patients. Neuroimaging shows enlarged extraocular muscles. Most children with this complication can be treated conservatively with topical lubrication, but orbital fat decompression may be considered in patients with more advanced conditions.

Streptococcal gangrene of the eyelids and orbit

PURPOSE

Streptococcal gangrene, also termed streptococcal necrotizing fasciitis, is resurgent but remains exceedingly rare. Ophthalmologists and dermatologists must be aware of streptococcal gangrene, as eyelids are the most commonly affected area of the head and neck.

METHODS

We studied two cases of streptococcal gangrene of the orbit with clinical manifestations indistinguishable from common nonnecrotizing orbital cellulitis.

RESULTS

Infection progressed with dramatic rapidity to produce eyelid necrosis, respiratory failure, sepsis, and severe permanent visual loss caused by ophthalmic artery occlusions. Histopathologic analysis disclosed vascular thrombosis, necrosis, acute inflammation, and the presence of gram-positive cocci. Cultures grew heavy group A beta hemolytic Streptococcus. The first patient was infected with M type 1 carrying exotoxins A and B. The second patient was also infected with Streptococcus carrying exotoxin A.

CONCLUSION

Early diagnosis of this life-threatening infection is of paramount importance because survival may depend on early surgical debridement.

Endoscopy and biopsy of the orbit

Flexible endoscopes produce high-quality images, are small in size, and can deliver microsurgical instruments or laser probes. Early attempts at orbital endoscopy were limited by the relatively large size and poor visualization of rigid endoscopes. We performed endoscopic orbital exploration using the Olympus HYF flexible endoscope in four live dog orbits. We achieved excellent visualization of orbital structures including the globe, blood vessels, extraocular muscles, intermuscular septa, optic nerve, and fat. Visualization, hemostasis, and dissection were aided by the use of hyaluronic acid infused through the endoscope. We biopsied fat and extraocular muscle without complication using Olympus endoscopic cup biopsy forceps (confirmed by histopathologic examination). Our experience indicates that orbital endoscopy aided by viscoelastic hydrodissection may permit a less invasive approach to optic nerve sheath fenestration, tumor biopsy and treatment, and the removal of foreign bodies.

Orbital fat removal. Decompression for Graves orbitopathy

BACKGROUND

Orbital decompression has been used to describe surgical procedures that remove some portion of the orbital walls to reduce pressure on the orbital contents. Substantial morbidity associated with these procedures includes infraorbital anesthesia, worsened extraocular motility, globe displacement, and blindness. The authors believe that orbital contents also may be decompressed by removing orbital fat.

METHODS

Eighty-one patients with nonactive Graves orbitopathy were selected for orbital fat decompression based on the presence of proptosis and associated signs and symptoms to avoid bone removal. Soft-tissue analysis by computed tomography (CT) scan showed distended pockets of fat extending into the intraconal space, which were removed through medial-upper and lateral-lower anterior orbitotomies. Decompression with bone removal was reserved for those few patients with compressive optic neuropathy unresponsive to medical treatment and those patients with residual deforming exophthalmos after fat removal.

RESULTS

One hundred fifty-eight fat decompressions were performed on 81 patients over 9 years. The authors measured an average reduction in proptosis of 1.8 mm (range, 0-6.0 mm). The greatest average reduction in proptosis (3.3 mm) was produced in patients with preoperative Hertel measurements of greater than 25.0 mm. Morbidity was limited to temporary motility impairment of the inferior oblique in two patients.

CONCLUSION

The concept of orbital decompression can include removal of orbital fat to reduce proptosis, eliminate symptoms, and improve appearance with far less morbidity than when bone decompression is used as the primary decompressive procedure.

Orbital lymphangioma. Correlation of magnetic resonance images and intraoperative findings

BACKGROUND

Orbital lymphangiomas generally are invasive, slow-growing lesions that can produce proptosis, motility impairment, and compressive optic neuropathy. Successful surgical management requires detailed preoperative radiologic imaging with the capacity to determine the location and size of the tumors, the presence of cystic or solid components, and extent of infiltration of the tumor into normal orbital structures.

METHODS

The records of 12 patients with orbital lymphangioma were reviewed with attention to the clinical, radiologic, operative, and histologic findings.

RESULTS

Preoperative magnetic resonance imaging (MRI) produced highly detailed renderings of the orbital mass that were both diagnostic and predictive of the intraoperative findings. Magnetic resonance imaging was particularly sensitive to the presence of cysts within the tumor and was able to predict the contents of the cysts.

CONCLUSION

Using preoperative MRI, a more detailed and accurate surgical plan can be formulated than with any other noninvasive technique.

Evaluation of a collagen/hydroxylapatite implant for orbital reconstructive surgery

A variety of autogenous and alloplastic materials have been used to correct enophthalmos. Hydroxylapatite (HA), is a calcium-phosphate-based compound that has been extensively studied as a bone replacement material. We studied the properties of a new dense particulate form of HA in a collagen matrix (PFC/HA) implanted in the subperiosteal space of ten rabbit orbits for a period of 6 months. All animals were studied with pre- and postoperative computed tomography (CT) scans, and measurements of induced proptosis and implant volume were made. The proptosis induced by the implant averaged 2.2 mm and was stable over a 6-month period. Implant volume was constant throughout the study. Three-dimensional computer-generated images of the soft tissue, skeletal, and implant surfaces confirmed the implant stability. All animals were studied histologically with fluorochrome bone markers, which revealed minimal foreign body reaction to the implant, no evidence of infection, and marked fibrovascular ingrowth. We found the PFC/HA to possess properties that make it an ideal implant material: ease of availability, ease of handling, no resorption, minimal immunogenicity, infection resistance, no observed migration, biointegration, and no risk of disease transmission. PFC/HA may make an excellent implant material to manage orbital volume.

Re-examination of peripheral blood T cell subsets in dysthyroid orbitopathy

Patients with dysthyroid orbitopathy (DO) were grouped according to a multifactorial assessment of disease severity and the rate of disease progression. Using this system and flow cytometric measurements of T cell subsets in the peripheral blood, a significant increase in the percentage of CD4+ lymphocytes correlated with disease severity in DO patients with progressive disease. These observations are consistent with the hypothesis that the CD4+ peripheral blood T helper cells play a significant role in the progression of DO.

Correlation of serum immunoglobulin E elevations with clinical stages of dysthyroid orbitopathy

Total immunoglobulin E (IgE) was measured by an enzyme-linked immunoassay in serum samples from patients with dysthyroid orbitopathy and from a group of healthy volunteers. All the serum donors had no symptoms of allergy or infection and were not given any immunoregulative treatments for at least 6 months before the sampling. One hundred thirty-seven dysthyroid orbitopathy patients were rated clinically as belonging to one of the following groups: (1) stable dysthyroid orbitopathy; (2) active dysthyroid orbitopathy; (3) chronic or recurrent dysthyroid orbitopathy; or (4) dysthyroid orbitopathy characterized by limited myopathy. The serum IgE levels of all these groups were compared with 26 healthy, nonatopic volunteers. The mean IgE levels of groups 3 and 4 were significantly higher than the mean IgE level of the control group as well as that of the group with stable dysthyroid orbitopathy. Furthermore, serial readings on several patients were consistent with the hypothesis that serum IgE is elevated in connection with certain stages of rapid dysthyroid orbitopathy progression and also with two unusual clinical forms of dysthyroid orbitopathy.

Choristoma of the optic nerve and chiasm

A 21-year-old patient with a biopsy-proved choristomatous malformation of the optic nerve and chiasm is presented. The patient experienced progressive unilateral vision loss and optic atrophy. A gadolinium-enhanced magnetic resonance image demonstrated chiasmal involvement that was not evident on computed tomographic scan or visual field testing. We believe this is the third reported case of a choristomatous malformation of the optic nerve and chiasm and the first report of magnetic resonance imaging findings.

Comparative evaluation of blood schizontocidal activity of quinine and quinidine against drug resistant rodent malaria

Blood schizontocidal activity of quinine and quinidine has been compared against sensitive as well as chloroquine/mefloquine/quinine resistant strains of Plasmodium berghei and a multiple resistant strain of P. yoelii nigeriensis in Swiss mice. Evaluation of results on ED50/ED90 basis has shown distinct superiority of quinidine over quinine against sensitive as well as drug resistant strain of rodent malaria.

Treatment of acute Graves orbitopathy

The therapeutic options for the treatment of acute Graves orbitopathy include high-dose oral corticosteroids, surgical decompression, and radiotherapy. The former two treatments are associated with significant morbidity. Although there have been a number of reports of the efficacy of radiotherapy, its role in the management of this disease is still questioned. The authors reviewed 84 cases of acute Graves orbitopathy treated with either high-dose systemic corticosteroids or radiotherapy (2000 rad to each involved orbit). Radiotherapy resulted in significant improvement in subjective and objective signs of orbital congestion and was more effective than high-dose corticosteroids in relieving compressive optic neuropathy. Of the patients with compressive optic neuropathy, only 1 of 29 treated with radiotherapy required surgical decompression, whereas, 6 of 16 treated with corticosteroids required surgery. This study suggests that radiotherapy has greater efficacy and fewer complications than high-dose systemic corticosteroids in the treatment of acute Graves orbitopathy.

Eyelid lipoid granuloma following topical ointment application

Subcutaneous lipogranulomas have been known to occur after injection of lipids for cosmetic or therapeutic reasons. Fibrosis may occur around the granulomas, giving them a lobulated appearance that can clinically mimic a malignancy. Of the few reports of lipogranulomas after the use of topical ointment, none have occurred in the eyelid. We report a case of subconjunctival lipogranulomas after the use of topical ointment whose clinical appearance was suggestive of sebaceous gland carcinoma.

Ultrastructural comparison of erythrocytic stages of experimentally selected drug resistant strains of rodent malaria parasite P. berghei with its susceptible strain

Studies on ultrastructure of drug-resistant strains of Plasmodium berghei have been mostly restricted to the experimentally selected chloroquine and pyrimethamine resistant strains. Study of the morphology of mefloquine and quinine resistant strain of P. berghei has been carried out to demonstrate some differences between normal and drug-resistant strains. The main differences are concerned with a complex physiological process i.e., food ingestion and digestion. E.M. studies reveal that in the sensitive strain of P. berghei the trophozoites possess numerous rod-shaped malarial pigment particles which lie within a vesicle. In the trophozoites of resistant parasites the malarial pigment particles are rarely visible. Trophozoites of the sensitive strain have only one large food vacuole while the trophozoite of the resistant parasite contains 2-3 smaller vacuoles.

Passage of somatostatin analogue across human and mouse skin

Recent studies have documented beneficial effects of the somatostatin analogue, SMS 201-995 (hereafter referred to as SMS), when administered subcutaneously to patients with a variety of disorders. Since SMS is a small peptide, we tested the ability of two penetrant enhancers--dimethylsulfoxide and N-decylmethylsulfoxide (C10MS)--to promote transcutaneous passage of SMS. Samples of skin from human cadavers and hairless mice were tested in a static diffusion chamber. Application of SMS in conjunction with 1% C10MS resulted in rapid transdermal passage of SMS. These data were confirmed for hairless mouse skin in experiments with a modified diffusion chamber having continuous flow-through of receptor fluid in the subdermal reservoir. In this system, the cumulative amount of SMS that permeated hairless mouse skin was 20 micrograms/cm2/24 hours. Topical application of SMS with C10MS beneath a patch to mice confirmed in vitro data. Topical application of 10 micrograms of SMS resulted in plasma SMS levels of greater than 8,000 pg/ml within 2 hours. We conclude that SMS will cross both human and mouse skin, with a clinically significant flux, when administered topically with C10MS. The data support the feasibility of in vivo human trials of topical SMS therapy.

Loss of infectivity for Swiss mice of a mefloquine-resistant strain of plasmodium berghei

A strain of Plasmodium berghei made resistant to a 244 mg/kg daily dose of mefloquine by interrupted subcurative therapy in successive passages in weanling rats, was maintained for more than six months under drug pressure and was cryopreserved. Experiments with this strain have shown its loss of virulence for intact mice. In splenectomized Swiss mice infection with this resistant strain is transient. The mefloquine resistance of this line was unstable and the strain became sensitive to mefloquine after 10 serial drug-free passages but did not recover its infectivity to mice.

Schizontocidal activity of antibiotics against blood-induced Plasmodium gallinaceum infection

Comparative studies on the blood schizontocidal activity of antibiotics against Plasmodium gallinaceum infection of chicks have shown that doxycycline, minocycline, demeclocycline, tetracycline and oxytetracycline possess high antimalarial activity as judged by suppression of parasitaemia and extension of survival period. Of these, demeclocycline, tetracycline and oxytetracycline were effective only at high dose level. Chloramphenicol, erythromycin and gentamicin were relatively inactive. Treatment in 5- to 6-day-old established infection of chicks has shown that doxycycline and minocycline are relatively more effective than oxytetracycline and tetracycline in controlling acute infection.